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The characteristics of the multi-strut equipped large aspect ratio supersonic combustor fueled with liquid kerosene were observed to deepen understanding of the combustion characteristics. Some numerical simulations and experiments have been carried on at the condition of Tt = 1680K, Pt = 1.68Mpa, and Ma = 2.8. The mixing and combustion performances of liquid kerosene under the different fuel injection methods are studied by numerical calculation. The results show that with the multi-struts injection method, the fuel distribution can be optimized, and combustion performance is improved by 60%. Then, three different strut arrangement schemes are proposed by designing the relative position between the leading edge shock wave of the ignition strut and the injection strut. The shock field structure and total pressure loss in different cases are discussed, and a low-resistance strut arrangement scheme is obtained. The mixing efficiency of the liquid fuel is discussed, and the effect of the shock wave on the fuel vaporization process is analyzed by using the two-phase flow model. The results show that the process of fragmentation and atomization of the gaseous fuel is promoted by the shock wave, which improves the mixing efficiency. The influence of the arrangement scheme of the multi-struts on the combustion efficiency is analyzed. The degree of flame overlap increases rapidly at a small distance between struts, which makes the combustion efficiency drop by 30%. Finally, combined with the research contents of this paper, a design method of the multi-strut arrangement scheme is proposed, and the feasibility of the design method is verified by experiments. The results of this paper are beneficial for the future performance optimization of multi-strut combustors using liquid kerosene as fuel. [ABSTRACT FROM AUTHOR]

Hydrocracked kerosene represents an additional source of jet fuel in oil refineries. The objective of this study was to re-distill hydrocracked kerosene (distillation range of 155-211 °C) into narrow cuts (distillation range of 10 °C) and to determine the dependence of the critical parameters of jet fuel, i.e., density, aromatics, smoke, and freezing point on the mean boiling point (tmean) of these cuts, utilizing modern and well established analytical methods. Re-distillation yielded seven narrow cuts composed of hydrocarbons with maximally three different carbon numbers. The analyzed properties deteriorated significantly with increasing tmean of cuts. Already the cuts with tmean of 190 °C + did not meet the jet fuel specification for aromatics and the 210 °C + cut did not meet any of the studied properties. Aromatics were crucial in controlling the distillation range and this provided an explanation for why hydrocracked jet fuel can be produced only as a narrow fraction. Since a low freezing point characterized all narrow cuts, this property represents a crucial synergy of blending of the hydrocracked kerosene with a straight-run kerosene or SAF. Overall, we demonstrated that narrow-cut research provides new insights into the characteristics of the hydrocracked kerosene. [ABSTRACT FROM AUTHOR]

In this study, the differences in the combustion process of ammonia-premixed ignition with conventional diesel and kerosene as pilot fuels were investigated based on flame chemiluminescence, and further study on the effects of ammonia ratio (AMR) and direct injection timing (DIT) on the ammonia-kerosene dual-fuel combustion (AKDC) process was carried out. The results show that the kerosene with stronger volatility is more conducive to promoting rapid and stable combustion of ammonia. A composite flame structure is observed in dual-fuel modes. With the increase of AMR, the capacity to ignite ammonia is lessened, the flame area and luminosity are stabilized and then reduced, and the flame hue is transformed from blue-green to yellow. Higher combustion rates are observed when the DIT lies between −9° and −12° CA ATDC, resulting in higher flame area and luminosity. The overly advanced or delayed DIT leads to the deterioration of ammonia combustion. • An optical study of the AKDC and ADDC mode was conducted. • A composite flame structure is observed in AKDC and ADDC modes. • Kerosene is more conducive to the ignition of ammonia than diesel. • As AKDC phases are roughly the same, the combustion state of pilot fuel dominates. • Adjusting the phase of AKDC towards TDC via DIT helps the rapid combustion of it. [ABSTRACT FROM AUTHOR]

In order to study the effect of coal-based kerosene on physical and chemical properties of jet fuel, the coal-based kerosene has been added to jet fuel, and the more than 20 kinds of physical and chemical properties of jet fuel have been tested according to national standard«No.3 jet fuel» (GB 6537). The results show that the physical and chemical properties of jet fuel containing coal-based kerosene meet the requirements of national standard «No. 3 jet fuel» (GB 6537). When the volume content of coal-based kerosene increases, 11 kinds of properties of the jet fuel behave monotonic variation, 13 kinds of properties keep unchanged. It can be seen that jet fuel containing coal-based kerosene still meets the requirements of national standard «No. 3 jet fuel» (GB 6537), whereas the coal-based kerosene has different influence on properties of jet fuel. [ABSTRACT FROM AUTHOR]

This study investigates the performance and environmental impact of n-butanol blended with Jet-A fuel in turbo engines, aiming to assess its viability as a sustainable aviation fuel (SAF). The research involves the experimental testing of various blends, ranging from low to high concentrations of n-butanol, to determine their effects on engine performance and emissions. The experimental setup includes comprehensive measurements of engine parameters such as thrust, fuel consumption rates, and exhaust gas temperatures. Emissions of sulfur dioxide (SO2), and carbon monoxide (CO) are also analyzed to evaluate environmental impacts. Key findings indicate that n-butanol/Jet-A blends can significantly enhance combustion efficiency and reduce emissions compared to conventional Jet-A fuel. Higher n-butanol concentrations lead to improved thermal efficiency and lower SO2 and CO emissions. This study underscores the potential of n-butanol as an SAF for turbo engines, highlighting its ability to mitigate environmental impacts while maintaining or improving engine performance. This research supports the feasibility of integrating n-butanol into Jet-A blends for turbo engine applications, emphasizing their role in achieving more environmentally friendly aviation operations. [ABSTRACT FROM AUTHOR]

The aerosol emission measurement at sources is crucial for effective environmental regulations and upgradation to global air quality standards. In the present study a Versatile Source Sampling System (VS3) has been designed, fabricated and evaluated to capture emissions from various sources. This study addresses key operational challenges such as isokinetic conditions for aerosol collection, mimicking rapid exhaust and zero-air mixing for gas-to-particle partitioning, and maintaining uninterrupted power supply. Depending upon the emission source, i.e., area, line or point, the aerosol sampling probes and a portable ejector dilutor with dilution tunnel were designed and evaluated in the laboratory and on-field for mixing and particle losses at three dilution ratios 20:1, 30:1, and 40:1. Particle loss experiments were done with sodium chloride and polystyrene latex aerosols. The on-field measurements were carried out with diesel generator, truck and light motor vehicle-goods. The overall particle losses were found to be 8% in the inlet designed for area source measurement, 1-3% for the ejector with dilution tunnel, and 9% and 13% for line and point source sampling inlets, respectively. There was no significant change (p-value > 0.05) in the average particle geometric mean diameter inside the dilution tunnel at different dilution ratios indicating no coagulation. For the first time, this study has reported the PM2.5 (particles with aerodynamic diameter <2.5 µm) emission factor of kerosene fuel used in diesel generator in rural areas for commercial use with values identified between 44 ± 16 gkg−1 accounting 30% Organic Carbon (OC) and 16% Elemental Carbon (EC). [ABSTRACT FROM AUTHOR]

The aim of this work is to describe an approach to the formulation of surrogates of hydrocarbon fuels, taking into account the properties related to atomization, heating, evaporation and combustion behaviors. These properties include the density, viscosity, lower calorific value, distillation curve, saturated vapor pressure, heat capacity, thermal conductivity, surface tension, molar ratio of hydrogen to carbon, molar mass, derived cetane number, and threshold soot index. Three diesel surrogates were developed using the proposed approach. Methods for calculating the physicochemical properties of both individual hydrocarbons and their mixtures are presented. The discrepancy between calculated results and experimental data for all properties is shown not to exceed 3%. Experimental studies were carried out in a lab-scaled combustion chamber, in which the properties of one of the three developed surrogates, DSSU3, were compared with those of diesel fuel. Also, the simulation results for DSSU3 were compared with published experimental data. It is shown that the properties of DSSU3 are a good match for those of diesel fuel. In addition, a kerosene surrogate was formed using the proposed approach. This allowed us to conclude that this approach to determining the properties of multi-component fuels is suitable for the formulation of both kerosene and diesel fuel surrogates. [ABSTRACT FROM AUTHOR]

This study explores the sorption capacity and field application of activated carbons (ACs) derived from plant residues for the remediation of oil-contaminated soils. ACs were prepared from rice husks, reed stalks, pine sawdust and wheat straw using two-stage pyrolysis and chemical activation with potassium hydroxide. The structural and physicochemical properties of these ACs were analyzed using BET surface area measurements, SEM analysis, Raman spectroscopy and FTIR spectroscopy. Sorption experiments at room temperature demonstrated that AC from rice husks (OSL) exhibited the highest sorption capacities for gasoline, kerosene and diesel fuel, with values of 9.3 g/g, 9.0 g/g and 10.1 g/g, respectively. These results are attributed to the well-developed microporous and mesoporous structures of OSL, as confirmed by SEM images and a BET surface area of 2790 m2/g. Field tests conducted at the "Zhanatalap" oil deposit showed that the ACs effectively reduced the oil content in contaminated soils from 79.2 g/kg to as low as 2.6 g/kg, achieving a purification degree of up to 67% within 16 days. This study highlights the critical role of structural properties, such as porosity and graphitization degree, in enhancing the sorption efficiency of ACs. [ABSTRACT FROM AUTHOR]

Micro reciprocating piston internal combustion engines are potentially desirable for high-energy density micro power sources. However, complex subsystem functions hinder the downsizing of reciprocating piston internal combustion engines. The homogeneous charge compression-ignition (HCCI) combustion mode requires no external ignition system; it contributes to structural simplification of the reciprocating piston internal combustion engines under a micro space constraint but has not been adequately verified at the millimeter scale. The study used a millimeter-scale HCCI reciprocating piston internal combustion engine fueled by a mixture of kerosene, ether, castor oil, and isopropyl nitrate for combustion investigation. The test engine with a displacement of 0.547 cc is the smallest reciprocating piston internal combustion engine known to have undergone in-cylinder combustion diagnosis. It is observed that the HCCI combustion mode at the millimeter scale can realize stable combustion with excellent cooperation for the thermodynamic cycle under appropriate structural and operating conditions, which is essentially not inferior to those in conventional-sized reciprocating piston internal combustion engines. This finding helps the next step of scaling down reciprocating piston internal combustion engines. [ABSTRACT FROM AUTHOR]

Aviation kerosene is a high-density, high-calorific value fuel widely used in high-velocity oxygen fuel (HVOF) thermal spraying. However, incomplete combustion of aviation kerosene generates CO2, CO, and unburned hydrocarbons, which are not conducive to sustainable development for industry. Research on new HVOF processes using clean fuels is significant for energy conservation and emission reduction. In this study, a two-dimensional numerical model of JP-8000 spray gun flow field was established based on the computational fluid dynamics method, and the ethanol was blended into aviation kerosene fuel to reduce carbon emissions during spraying. Ethanol-kerosene premixed fuel and WC-12Co particles were injected into spray gun in discrete phase form. The KHRT method and O 'Rourke method in the discrete phase model were used to deal with the breakup and coalescence of fuel droplets. Lagrange tracking method was used to capture the flight trajectory of fuel droplets and sprayed particles, and the gas–liquid–solid coupling calculation of spraying flow field was realized. The results show that adding ethanol to aviation kerosene fuel can effectively reduce CO2 emissions. When the ethanol proportion is 10%, CO2 emissions decrease by nearly 30%. Ethanol pyrolysis leads to a slight increase in CO emissions, which can be effectively reduced by appropriately increasing the oxygen/fuel ratio. This study provides an important theoretical basis for the spraying practice of HVOF mixed fuel for energy saving and environmental protection and offers new insights for further optimizing the spraying process. [ABSTRACT FROM AUTHOR]

In this work, for the first time, various surfactants such as oleic acid, oleylamine, Tween 20 and Span 20 were used as static dissipating additives (SDA) for kerosene fuel to enhance their electrical conductivity. The ability of the surfactant dispersed kerosene fuel to store, transport, and process was revealed in terms of process safety parameters such as electrical conductivity, retention period, and viscosity. The results indicated an enhancement of the electrical conductivity of the kerosene fuel up to 1689 pS/m for a 500 ppm addition of surfactants. The surfactant dispersed fuel was measured for electrical conductivity with a varying temperature range from 30 to 70 °C. The addition of 0.05% by weight surfactants increased the viscosity of the kerosene fuel by 20.7%, however, without degrading the fuel quality. A laudable reduction in the retention period of 10 days was also observed. This study revealed that the surfactants selected in this study are found to be potential additives to reduce the ignition hazards of kerosene fuels. [ABSTRACT FROM AUTHOR]

Relative humidity with respect to ice (RH i) is a key variable in the formation of cirrus clouds and contrails. We document its probability density function (PDF) using long-term Measurements of Ozone, Water Vapour, Carbon Monoxide and Nitrogen Oxides by In-Service Airbus Aircraft (MOZAIC) and the In-service Aircraft for a Global Observing System (IAGOS) observations over the period 1995–2022 in the upper troposphere (UT) and the lower stratosphere (LS) between 325 and 175 hPa. The characteristics of the RH i PDF differ in the UT and in the LS of the high-latitude regions (HLs) and mid-latitude regions (MLs) of the Northern Hemisphere. In the LS, this PDF decreases exponentially with increasing RH i. In the UT, it first increases exponentially in subsaturated conditions and then decreases exponentially in supersaturated conditions. Because of these different behaviors, the PDF for the combined UT and LS is bimodal. In contrast to the HLs and the MLs, the RH i PDF in the tropical troposphere decreases exponentially with increasing RH i. The different forms of PDF, in the tropics and in the higher-latitude regions, lead to a global PDF of RH i in subsaturated tropospheric conditions that is almost uniform. These findings invite caution when using MOZAIC and IAGOS measurements to calibrate large-scale simulations of RH i. The variability in RH i properties associated with that of temperature also has implications for the formation of contrails. We examined the impact of switching fuel (from kerosene to bioethanol or liquid hydrogen) on the frequency of contrail formation using the Schmidt–Appleman criterion. We show that bioethanol and, to a larger extent, liquid hydrogen would produce more contrails. The impact of a potential change from kerosene to these alternative fuels decreases with decreasing pressure but increases when moving from the higher latitudes of the Northern Hemisphere to the tropics. Finally, we emphasize that investigations of the impact on contrail occurrence frequency as a result of switching from fossil kerosene to more sustainable fuels must be carried out in various meteorological conditions. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the impact of diesel and kerosene on the transient processes occurring in a micro-turbojet aviation engine. The experiments were conducted under two distinct ambient temperature conditions, 0 and 20 °C. Specifically, we analyzed the starting phase of the micro-engine while operating with kerosene and diesel at both ambient temperature settings. Comparative graphs were generated, and the starting time was meticulously examined. Subsequently, we constructed performance maps for the engine using both fuels and across the two ambient temperature scenarios. We then executed a transient process, comprising sudden acceleration and deceleration, under the aforementioned ambient temperature conditions and with both fuels. The fluctuations in temperature within the combustion chamber, thrust force, and fuel consumption are presented for both rapid acceleration and deceleration events. Furthermore, we conducted comparisons between the thrust force, fuel flow rate, combustion chamber temperature, and specific fuel consumption for the two fuels tested and under the two ambient temperature conditions, both during idle and at higher engine regimes. In the idle regime at 0 °C, the kerosene flow is about 0.78% higher than diesel, with the kerosene thrust approximately 1.92% greater. At 20 °C, the kerosene consumption rises by roughly 5.56% compared to diesel, while the thrust increases by about 1.38%. It was observed that at the maximum operating regime, at 0 °C, the kerosene flow exceeds diesel by around 6%, with the kerosene thrust slightly higher, by about 0.63%. At 20 °C, the kerosene consumption rises by roughly 13.19% compared to diesel, while the thrust increases by about 5.91%. In higher regimes, the kerosene consumption surpasses diesel, but the thrust increase is not significant. Thus, diesel's use as a fuel for the microturbo engine is justified due to its lower consumption at both 0 °C and 20 °C. [ABSTRACT FROM AUTHOR]

The application of hydrogen for fuel enrichment and blending has recently gained importance. The sustainability and performance enhancement through hydrogen addition in flameless combustion mode for liquid fuels needs further investigation to enhance our understanding. Therefore, the present study reports the effect of hydrogen addition on the flameless combustion of a kerosene-fired 30 kW swirl combustor with hydrogen addition. A divergence-shaped conical combustor with tangential air injection and asymmetric fuel injection scheme is adopted. The liquid fuel was injected using a solid-cone swirl nozzle with 34 μm Sauter Mean Diameter. The hydrogen addition was varied from 0 to 20% on a thermal input basis, and the thermal input of liquid fuel was maintained at a 30 kW level. Computational studies helped understand the flow physics behavior within the combustor volume. The hydrogen addition was observed to improve the reactant dilution ratio (R dil). The maximum values of the R dil increased from 4.47 to 5.44 with hydrogen addition. Hydrogen addition further helped extend the flameless combustion regime to φ = 0.3 without any air preheating. A uniformly distributed reaction with a reduced-temperature gradient is observed with extended combustion stability limits. A marginal increase in NO x emissions was observed with hydrogen addition, albeit within permissible limits, accompanied by ∼8–20 dB reduction in acoustic emissions. [Display omitted] • Effect of H 2 addition in flameless combustion is studied with kerosene. • H 2 in flameless combustion, enhancing sustainability via wider flammability limits. • H 2 improves temperature uniformity, minimizing temperature gradients. • H 2 addition reduced the CO emissions. [ABSTRACT FROM AUTHOR]

The dynamically growing sustainable aviation fuel (SAF) industry and the implemented European policy create the need for conducting research on the actual benefits of using alternative fuels in aviation. The aim of this research was to assess the impact of HEFA (hydroprocessed esters and fatty acids) fuel on the particulate matter emission indicators of an aircraft engine. This article presents the results of the measurements of particle emissions from a jet engine fueled by a blend of aviation kerosene and HEFA fuel (with HEFA content at 5%, 20%, and 30% by volume). A positive effect of HEFA on both the number and mass indices of particles was observed. The use of SAF fuel led to a reduction in the particulate number index by 90% and the particulate mass index by 75%. The Particle Number Emission Index (EIN) for an engine fueled with Jet A-1 exhibited values ranging from 5.23 × 1016 to 1.33 × 1017 particles per kilogram. The use of HEFA fuel (30% content) allowed for a reduction in the EIN to the range of 2.83 × 1015 to 1.04 × 1016 particles per kilogram. A detailed analysis of particle size distribution (PSD) for both the number and volume of particles was conducted. It was noted that neither the fuel composition nor the engine operating parameters significantly affected the shape of the PSD, but the use of HEFA fuel distinctly reduced the values of the number-based PSD. It was observed that the volume-based PSD had a bimodal shape, indicating a significant contribution of particles larger than 100 nm, forming the so-called soot mode. Our findings suggest that even a small amount of HEFA fuel yields satisfactory results in reducing particulate matter emissions. [ABSTRACT FROM AUTHOR]

In this numerical study, the heat transfers of two types of fuels, namely kerosene and gasoline, were studied within a wavy channel with pulsed flow. The CFD module at COMSOL Multiphysics was used in this study. Several variables were used and applied to both types of fuel and compared between them. These variables included the values of Reynolds numbers between 200 to 800, as well as several values of Strouhal Numbers between 0 to 0.25. Different variable values were also used for the wavy channel, including the wave numbers (0, 2, 4, 6, 8, 10) as well as variable values of the wave amplitude (0, 0.1, 0.2, 0.3). Through this study, it was observed that as Strouhal Numbers increase, there is an increase in the Nusselt Number value. It was also observed that as the number of waves increases, there is an improvement in the heat transfer values. The numerical results showed that the values of heat transfer improved with an increase in the amplitude of the wave.. [ABSTRACT FROM AUTHOR]

The aviation industry uses heavy hydrocarbon fuels, which release carbon-based emissions upon combustion and could suffer from flame stabilization issues due to their high Lewis numbers at lean conditions. Hydrogen is emerging as an alternative fuel which can help mitigate these issues. A viable strategy is to blend liquid hydrocarbons with hydrogen, which could strengthen the flame in positively stretched regions and help reduce carbon-based emissions. In order to investigate this, we carry out a numerical study for different blends of n-dodecane, which is a surrogate fuel for kerosene and jet fuel, with hydrogen in air. Equivalence ratios and unburnt temperatures of different blends are selected such that the laminar burning velocity remains the same. This condition allows for a more precise characterization of Lewis number effects manifested at the flame base and tip. It is found that up to 60 % addition of H 2 into n-dodecane by volume, no major difference is observable with respect to the flame stabilization process. The positively curved flame base burns weakly while the negatively curved flame tip is strengthened due to thermal diffusivity being greater than mass diffusivity. With a further increase in the percentage of hydrogen, the flame base starts to burn stronger with the flame moving closer to the flame holder. However, the flame tip does not become weak as n-dodecane continues to burn there. As positive stretch and negative curvature increase the consumption rate for H 2 and n-dodecane flames, respectively, for the blend with 95 % hydrogen and 5 % n-dodecane, a flame is observed with the flame base and the flame tip both burning strong. Overall, this demonstrates that introducing hydrogen at concentrations exceeding 60 % by volume significantly enhances flame stabilization by bringing the flame closer to the flame holder, potentially expanding flame stabilization boundaries. [Display omitted] • Addition of hydrogen into n-dodecane numerically analyzed for multi-slit flames. • Mixtures with the same burning velocity were selected for a fair comparison. • n-dodecane flames remain unaffected till 60 percent of hydrogen addition. • For higher hydrogen content, the flame base starts to burn strong due to Le < 1 effects. • The addition of hydrogen can help in the stabilization of n-dodecane flames. [ABSTRACT FROM AUTHOR]

In this CFD study conducted with the geometry of a mini gas turbine engine using kerosene as fuel, colorless distributed combustion conditions were achieved by increasing the N 2 ratio in the air. Then, H 2 was added to the kerosene fuel in order to increase the combustion performance and the combustion chamber temperature distributions, NO x , CO, and CO 2 values were examined. In the simulations using the simplified GTM-120 geometry, the combustion chamber outlet temperatures at 80 k, 100 k, and 120 k rpm were compared with the experimental results in the literature by changing the ratio of fuel and air for the validation study. Standard k-ε and Discrete Ordinates were chosen for turbulence and radiation models, respectively. In the study conducted with the non-premixed combustion model, simulations were made at O 2 rates of 21%, 19%, 17%, and 15% for the formation of colorless distributed combustion conditions. For enrichment with hydrogen, H 2 was added from 0% to 50% with 10% increments. HEF (Hydrogen energy fraction) has been used as the hydrogen addition rate. In light of the analyses made, it was seen that the colorless distributed combustion regime reduced the flame temperature from 2292 K to 1912 K and the NOx amount from 2.85 ppm to 0.0086 ppm. On the other hand, it is seen that this regime increased the CO emissions from 6.9 ppm to 38.67 ppm and the mole ratio of CO 2 from 6.25% to 6.94%. It was observed that these findings prepared the ground for increasing the amount of hydrogen in the fuel, which increases the flame temperature and, accordingly, NO x emissions. By adding 50% H 2 to kerosene under standard atmospheric conditions, the average NO x emission at the combustion chamber outlet increased from 2.85 ppm to 7.97 ppm, while the average CO emission decreased from 6.9 ppm to 1.08 ppm. As a matter of fact, by the addition of 50% H 2 to the kerosene with air that contains 15% O 2 , which is the most extreme combustion situation in this study, the flame temperature decreased to 1912 K, and NO x rose to 0.0713 ppm. However, the CO emissions at the combustion chamber outlet decreased to 1.83 ppm and the CO 2 ratio to 3.48%. Thus, with this study, it has become possible to use hydrogen as an alternative fuel in a real engine geometry by using CDC and hydrogen enrichment together, both in terms of pollutant emissions and combustion performance. • Colorless distributed combustion has been studied in a mini jet engine. • The effect of hydrogen addition on pollutant emissions was investigated. • Uniform thermal fields in the combustion chamber and ultra-low NO x emissions at the outlet have been obtained under CDC conditions. • In combustion with pure kerosene under CDC conditions, the mean NO x 0.0086 ppm and the mean CO 38.67 ppm were found at the combustion chamber outlet. • It has been observed that the addition of hydrogen reduces CO and CO 2 emissions. • By adding 50% H 2 to the kerosene with air containing 15% O 2 , the mean NO x 0.0713 ppm and mean CO 1.83 ppm were found at the combustion chamber outlet. [ABSTRACT FROM AUTHOR]

A comprehensive CFD model is developed to predict soot for a turbulent kerosene-air diffusion flame. The method of moments (MOM) soot model has better prediction capability with meaningful soot behavioral predictions than semi-empirical models. The coupled model is primarily validated with experimental measurements from the literature in the form of major species concentration, flame temperature, and soot volume fraction. A surrogate mix comprising 80% n-decane and 20% toluene on a liquid volume basis constitutes kerosene fuel. The 20% aromatic content is able to reproduce the sooting behavior with considerable accuracy. The model can replicate CO, CO2, CH4, C2H2, C2H4, and C6H6 concentrations, flame temperature, soot volume fraction, and soot aggregation parameters for a laminar JetA-1 flame at atmospheric pressure. The reproduction of flame temperature and major species concentrations for a laminar kerosene flame validates the applicability of the gas-phase kinetic mechanism and PAH formation pathway for the reacting flow system. The model also performs appreciably for measurements of a turbulent kerosene flame at higher operating pressures up to 6.44 bar. The peak soot volume fraction matches significantly well with the measurements for all the flames. The predicted peak soot volume fractions are 8.8, 27.3, 68, and 82 ppm compared to measured values of 9.3, 28.3, 63, and 67 ppm at pressures 1, 2.7, 4.81, and 6.44 bar, respectively. However, the location of the peak soot has a slight discrepancy at low pressures till 2.7 bar, showing the predicted peak earlier compared to a later appearance in the measurements. The simulated peak flame temperatures are 1377, 1393, 1412, and 1477 K as operating pressure increases from 1 to 2.7, 4.81, and 6.44 bar. The thermal absorbance from soot and species radiation plays a vital role in predicting the flame temperature. Soot radiation reduces flame temperature by ~ 500 K compared to gaseous radiation (CO2, H2O, CO, CH4, etc.), reducing approximately 100 K. The predictive soot number density, mean diameter, surface area, primary particle count in soot aggregates, and primary particle diameter carry a substantial dependency on the operating pressure. [ABSTRACT FROM AUTHOR]

Background Unclean cooking fuels (ie, polluting fuels including kerosene/paraffin, and solid fuels) are a major contributor to diseases and mortality, specifically in low- and middle-income countries. Methods This review aimed to identify potential mechanisms, public health implications, and future directions of unclean cooking fuel use and health outcomes in older adults. Results There is an expanding body of literature to demonstrate associations between unclean cooking fuel use and multiple mental and physical health outcomes in older adults. Two key mechanisms likely driving such associations include inflammation and oxidative stress. Conclusions Considering that inflammation and oxidative stress have been implicated in multiple other health conditions (eg, arthritis and osteoporosis) in addition to those investigated to date on this topic it would be prudent to continue investigation of unclean cooking fuel use and with yet to be studied health outcomes. Moreover, future research is indeed now required to identify pathways to eliminating unclean cooking fuel globally to better the health of an aging global population and to support the implementation of Sustainable Development Goal 7. [ABSTRACT FROM AUTHOR]

The lean blowout (LBO) limit is crucial for gas turbine combustor in the aero engine. The effect of atomization of liquid fuels on the LBO limit is needed to be further studied. On the other hand, the effects of atomization on the LBO limit can be neglected if gas fuels are utilized in a combustor. Thus, the comparative experiment between liquid fuel and gas fuel can be utilized to study the effects of atomization performance of liquid fuels on the LBO limit. In this paper, the LBO limit for a gas turbine combustor utilizing methane is studied experimentally. Seven kinds of combustor configurations are chosen for the experimental test. The LBO limits are obtained for all the chosen combustors. The variation of the LBO limit with the combustor configuration for both methane and aviation kerosene exhibits the similar tendency, i.e., the LBO limits utilizing methane are slightly larger than those utilizing aviation kerosene for the same combustor. Further, the atomization performance has little effects on the LBO limits for the present combustor configurations at the present operating conditions where the SMD for the fuel atomizer utilizing aviation kerosene is about 10 μm. [ABSTRACT FROM AUTHOR]

This study deals with the design of a suitable configuration of jet deflector for supersonic exhaust gases from a semi-cryogenic launch vehicle engine using computational fluid dynamics. Computational model of combustion in semi-cryogenic engine, with kerosene as fuel and liquid oxygen as oxidizer, was developed in which exhaust gases from engine were impinged on the deflector surface. Different design configurations of deflector structure, obtained by the combination of various impingement angles of 15°, 20°, 25°, 30°, and 45°, and different exit radii of 5000, 10 000, and 20 000 mm, were used in the developed computational models to analyze impingement, deflection, and associated flow properties of exhaust gases, such as acoustics, force on deflector imparted by jet, temperature, and Mach number of flow field. A new ablation model was developed based on Vieille's law to determine the amount of refractory material ablated from deflector structure for different configurations. The developed models of ablation, combustion, and flow impingement were also validated with existing literature. It was found that the configuration with 20° impingement angle and 10 000 mm exit radius had ablation, acoustics, force, and flow properties in desired limit. Furthermore, to find the optimum uplift angle for designing jet deflector, configurations with uplift angles of 0°, 5°, 15°, and 25° were studied using the computational models developed in the study. It was observed that the configuration with 20° impingement angle, 10 000 mm exit radius, and 15° uplift angle was best suited for impingement and deflection of exhaust jet from the specified semi-cryogenic engine. [ABSTRACT FROM AUTHOR]

In this study, numerical simulations based on an Eulerian-Lagrangian framework are conducted to investigate the liquid-fueled rotating detonation engine (RDE) with heterogeneous kerosene-hydrogen-air mixtures. The hydrogen addition is implemented for combustion enhancement of the liquid kerosene and helps to ignite and achieve a self-sustained two-phase rotating detonation wave (RDW). The effects of droplet evaporation at various initial droplet sizes and kerosene mass flow rates on the structure and propagation of the two-phase RDW are analyzed. Results suggest that with smaller droplet sizes, the structure of the RDW is analogous to that of a gaseous RDW, and a comparison with experimental data suggests that the estimated detonation speed and thrust performance (fuel-based specific impulse) are within the reasonable ranges. However, as the droplet size or the mass flow rate of kerosene increases, the two-phase RDW exhibits characteristic features such as the dual-front laminated structure, micro-explosions and secondary transverse waves. • Rotating detonation engines (RDEs) with a heterogenous kerosene-hydrogen-air mixture are investigated. • Numerical simulations based on an Eulerian-Lagrangian two-way coupled framework are conducted. • A dual-front rotating detonation wave (RDW) caused by droplet evaporation is explained. • Micro-explosions and secondary RDWs are captured at higher kerosene mass flow rates. [ABSTRACT FROM AUTHOR]

Addressing the burgeoning issue of polymer waste management and disposal, chemical recycling, specifically the production of highquality oil, presents an enticing solution. This research paper delves into the process of plastic waste pyrolysis, focusing on polypropylene, and thoroughly examines the physico-chemical properties of the resulting pyrolytic oil. The oils, obtained from waste plastic pyrolysis (referred to as WPPO), are then blended with kerosene and utilized as fuel for a gas turbine engine. The primary objective of this investigation is to ascertain how the blend composition influences the performance and emission parameters of the micro gas turbine. In our findings, it was observed that all tested waste plastic pyrolysis blends displayed a trend towards escalating regulated emissions such as nitrogen oxides (NOx) with an average increase of 26% for polypropylene pyrolysis oil (PPO). The emission index (EI) for carbon monoxide (CO) was found to be relatively consistent across all fuel blends tested in this study. Interestingly, when considering the thrust specific fuel consumption (TSFC) within the EI calculation, blends of aviation kerosene and plastic oil showed lower values in comparison to the pure Jet A-1 fuel. Furthermore, an augmentation in the proportion of WPPO in the blends consequently led to an elevation in the exhaust gas temperature (an average increase of 8.7% for PPO). Interestingly, the fuel efficiency of the Jet engine, expressed as TSFC, demonstrated a decrease, with an average reduction of 13.8% observed for PPO. [ABSTRACT FROM AUTHOR]

In this paper, the effects of the Tesla valve intake structure with or without bypass manifold on suppressing pressure feedback and combustion product backflow in rotating detonation engine fueled by kerosene and enriched air with 29% oxygen content are investigated, with the configuration of convergent–divergent intake without bypass manifold being used for comparison. The working range, detonation wave propagation characteristics, and propulsion performance for the three configurations are evaluated. It is found that the Tesla valve intake structure can effectively improve the suppression of pressure feedback and combustion product backflow through the diversion function of the Tesla valve bypass channel and that the addition of the bypass manifold further improves the suppression of pressure feedback. The Tesla valve intake with bypass manifold configuration has the best ability to suppress pressure feedback, with a minimum value of pressure feedback percentage of about 6.5% and a minimum value of air plenum pressure fluctuation percentage of about 6.7%. By comparison, the minimum value of pressure feedback percentage of the convergent–divergent intake without bypass manifold configuration is about 29.8%, and its minimum value of pressure feedback percentage is about 7.8%. The Tesla valve intake without bypass manifold configuration is most effective in suppressing combustion product backflow, with the effective inlet area ratio of about 95.7%. Under the same conditions, the minimum effective inlet area ratio of the convergent–divergent intake without bypass manifold configuration is about 90.2%. Ultimately, optimizing the engine structure leads to a broader working range and higher propulsion performance. The Tesla valve intake structure broadens the working range by suppressing the generation of the longitudinal pulsed detonation mode. When the bypass manifold is incorporated, some combustible reactants directly enter the rear of the combustion chamber from the head of the chamber, and the working range is reduced. Compared with the convergent–divergent intake without bypass manifold configuration, the working range of the Tesla valve intake with bypass manifold configuration is widened by 383.3%, and that of the without bypass manifold configuration by 700%. Both the Tesla valve intake and bypass manifold increase the strength of detonation waves and improve propulsion performance. The Tesla valve intake with bypass manifold configuration has the highest specific thrust, at about 90.1 N s3/(kg·m). This is increased by an average of 10% compared with the Tesla valve intake without bypass manifold configuration, and by an average of 30.1% compared with the convergent–divergent intake configuration. • Tesla valve inlet and bypass manifold are used to suppress feedback. • Two quantitative evaluation parameters of pressure feedback are established. • The degree of combustion product backflow is evaluated. • The optimized structure can effectively improve the propulsion performance. [ABSTRACT FROM AUTHOR]

By 2050, aviation-related carbon emissions are expected to quadruple to over 3000 million tonnes of carbon dioxide, so finding sustainable alternative solutions to minimise pollution is a key scientific challenge. Aviation gasoline and kerosene are currently used to power most jet engines. While battery-powered planes and planes that could utilise a cleaner fuel, such as hydrogen, are possible, the time scale required to improve and implement these technologies is distant, with air fleet turnover taking some 30 years. Existing jet engines could be modified to run on biodiesel, and considering the close similarity in fuel density to kerosene, could be a less disruptive approach to the industry. The sheer volume of biodiesel required remains a challenge, and certainly, using plant-derived oils grown on arable land is not acceptable, as it competes with food production. However, high-lipid-yielding microalgae (where productivity is an order of magnitude greater than oilseeds), grown on marginal land, such as desert or semi-desert areas of the world, could be possible. Indeed, to replace 30% of fossil fuel with algal-derived biodiesel would require 11,345 km2 of land. Biodiesel preparation is well understood, but what is lacking is proven technology aimed at optimising microalgal production of oil at a much larger scale. Here, a synergic review of the current state-of-the-art in algal production, that includes strain selection, possible production sites, culturing costs, and harvesting to identify the bottlenecks in meeting the ASTM specifications for the aviation industry, is presented. [ABSTRACT FROM AUTHOR]

The search for renewable, affordable energy alternatives has gained momentum in light of dwindling fossil fuel reserves. Biofuels, particularly those derived from plant sources, present a viable solution to both the energy crisis and environmental degradation. This study focuses on the implementation of olive oil methyl ester (OME) biofuel in micro gas turbine engines. Biofuel blends, with volumetric OME concentrations ranging from 20% to 80% in standard kerosene, were prepared and tested on a GT 85-2-H micro gas turbine unit. The engine's performance and exhaust emissions were evaluated under two different operational parameters: constant speed and constant load. The use of an 80% OME biofuel blend resulted in an 8.7% reduction in overall efficiency and a 13.1% increase in specific fuel consumption (SFC) under an 80% load. However, it also led to a significant improvement in exhaust emissions, with reductions of 28.8%, 39%, and 33.8% recorded for carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NOx), respectively. Similarly, under a constant speed test at 20000 rpm, an 80% OME blend caused a 10.5% reduction in overall efficiency and a 13.6% increase in SFC. Nevertheless, the same blend improved the CO, HC, and NOx emissions by 38%, 41.4%, and 36%, respectively. The findings confirm the potential of OME as a biofuel in micro gas turbine engines, underlining its effectiveness in reducing harmful emissions. This research emphasizes the feasibility of biofuels derived from olive oil in addressing future energy demands while mitigating environmental impact. [ABSTRACT FROM AUTHOR]

Studies of the influence of hydrocarbon rocket fuel kerosene T-1 on the physical and geochemical properties were carried out in laboratory circumstances on different types of soils: brown semi-desert soil designated as zone (U-25) located in Central Kazakhstan, mountainous brown desert soil zone (U-30) located in East Kazakhstan, and a model soil standard (control soil). The soil was treated with various concentrations (0.002–150.0 g/kg) of hydrocarbon rocket fuel kerosene T-1, while the contact time was 3, 10, and 30 days. Pollution with kerosene T-1 in concentrations 5.0–15.0 g/kg affects the hydraulic characteristics of soils from the U-25 zone, and the filtration rate decreases by 4–5 times. For the mountainous brown desert soil from the U-30 zone, the concentration of kerosene up to 15.0 g/kg does not affect the mechanical composition of the soil, as well as the availability of the main nutrients (potassium, phosphorus, nitrogen). According to the mechanical composition, both soils belong to medium loamy soils. It has been established that when soil is contaminated from the U-25 zone in concentrations 15.0–150.0 g/kg, the fraction from 1.0 to 0.05 mm increases by 4–5%, and the silty and clay fractions in the soil decrease. [ABSTRACT FROM AUTHOR]

Present work performs a comparative study of two medium-range commercial jets with future airframe and propulsion technologies powered by hydrogen and kerosene fuel to achieve a substantial reduction in overall aviation emissions. The study aims to investigate the cumulative effect of different energy networks combined with airframe efficiency gains achieved by aircraft-related technologies to suggest a better option for the potential next-generation commercial aircraft similar to the Airbus A320. Advanced airframe and engine technologies include laminar flow control, active load alleviation, new materials and structures, and ultra-high bypass ratio turbofan engines. Two aircraft with hydrogen and kerosene propulsion systems were sized to compare their performance characteristics, equivalent CO2 emission, and direct operating costs. The design was performed using a multi-fidelity approach and included the effects of future airframe technologies and the hydrogen propulsion system. The design comparison showed a significant contribution of airframe and propulsion technologies in achieving more environmentally friendly aircraft. The green hydrogen option showed a 41–63% reduction in overall emissions compared to the kerosene aircraft depending on flight conditions while the blue hydrogen variant achieved a 21–26% reduction level. A rather optimistic price scenario shall be met to enable an operational benefit of green hydrogen while the blue hydrogen variant has more potential of being economically acceptable by the market. In circumstances when operating costs drive the decision-making more than emissions, kerosene may be a more favorable option as a compromise between emission and costs, given the positive effect of airframe and propulsion technologies. [ABSTRACT FROM AUTHOR]

Self-immolation is the act of setting fire to oneself. Recent spikes in self-immolation events have been noticed in the Arab world, specifically in the aftermath of the Arab Spring in 2011. We aimed to examine the literature assessing the characteristics and patterns of suicide by self-immolation in the Arab world. We registered our systematic review in Prospero. We searched PubMed, Medline, PsycInfo, Embase, and Scopus databases from inception until 9 July 2022, along with other sources, following the PRISMA 2020 guidelines. We collected relevant articles tackling suicide by self-immolation in the Arab world via title and abstract screening followed by full-text screening. We then conducted a narrative synthesis of the results. Out of 326 records from databases and 17 additional records identified through other sources, 31 articles (27 quantitative and 4 qualitative) were included. The studies came from Iraq (n = 16), Tunisia (n = 6), Kingdom of Saudi Arabia (n = 3), Jordan (n = 2), Libya (n = 2), Bahrain (n = 1), and Egypt (n = 1). The quantitative studies had a sample size ranging from 22 to 600 self-inflicted burn victims. Studies showed that self-immolators were mostly married women with low educational level and low socioeconomic status. Self-immolation was more likely to happen at home, usually following marital conflicts. Kerosene was the accelerant used the most. Depression was the most comorbid mental health diagnosis. Studies highlighted that self-immolation was being increasignly used as a form of protest. Self-immolation is not uncommon in the Arab world. Specific interventions directed at the population at risk are warranted. • Self-immolation victims were commonly married females. • The most common triggers for self-immolation were familial and marital conflicts. • Either Kerosene or fuel was commonly used as accelerants. • The prevalence of mental illness among victims ranged from 5 % to 40 %. • The most reported psychiatric diagnoses were depression and schizophrenia. [ABSTRACT FROM AUTHOR]

In this study, a large-scale kerosene-fueled oblique detonation engine with a design point of Mach 10 is proposed. The flow combustion characteristics and the propulsive performance considering the wall viscous drag of the detonation engine are investigated using numerical simulation methods with a detailed combustion mechanism. The accuracy of the numerical results is verified by comparing it with the detonation wave pole curve of kerosene fuel. The result demonstrates that the combined injection method consisting of wall and center-strut injectors can meet the requirements of fuel mixing in the oblique detonation engine and a stabilized oblique detonation wave is successfully formed in the combustor. The decrease in the fuel equivalent ratio leads to an increase in the non-uniformity of the temperature distribution behind the detonation wave and the decrease in the wave angle. The advantage of the oblique detonation wave in hypersonic propulsion is its easy adjustment and can achieve flight over a wide-speed range. The combustion heat release behind the wave is closer to the upper part of the wave surface as the incoming Mach number decreases. The oblique detonation engine proposed in this study can still generate stable net specific impulse at non-design point flow Mach numbers. The net specific impulse can reach 715 s at a non-design point speed of Mach 8. It proves the feasibility of wide-speed range flight applications of oblique detonation engines. [ABSTRACT FROM AUTHOR]

Catalysts play a vital role in petroleum and chemical reactions. Intensified concerns for cleaner air with strict environmental regulations on sulfur content in addition to meet economic requirements have generated significant interests for the development of more efficient and innovative oxidative catalysts recently. In this study, a novel homemade nano catalyst (manganese oxide (MnO2) over tin (IV) oxide (SnO2)) was used for the first time as an effective catalyst in removing dibenzothiophene (DBT) from kerosene fuel using hydrogen peroxide (H2O2) as oxidant in catalytic oxidative-extractive desulfurization process (OEDS). The catalyst was prepared by impregnation method with various amount of MnO2 loaded on SnO2. The oxidation step was carried out at different operating parameters such as reaction temperature and reaction time in batch reactor. The extractive desulfurization step was performed by using acetonitrile as solvent under several operating conditions (agitation speed and mixing time). The activity of MnO2/SnO2 catalyst in removing various sulfur compounds from kerosene fuel at the best operating conditions was investigated in this work. The results of the catalyst characterization proved that a high dispersion of MnO2 over the SnO2 was obtained. The experiments showed that the highest DBT and various sulfur compounds removal efficiency from kerosene fuel under the best operating conditions (oxidation: 5% MnO2/SnO2, reaction temperature of 75 °C, and reaction time of 100 min, extraction: acetonitrile, agitation speed of 900 rpm, and mixing time of 30 min) via the catalytic oxidative-extractive desulfurization process was 92.4 and 91.2%, respectively. Also, the MnO2/SnO2 catalyst activity was studied after six consecutive oxidation cycles at the best operating conditions, and the catalyst prove satisfactory stability in terms of sulfur compounds removal. After that, the spent catalyst were regenerated by utilizing different solvents (methanol, ethanol and iso-octane), and the experimental data explained that iso-octane achieved highest regeneration efficiency. [ABSTRACT FROM AUTHOR]

Spark ignition (SI) engines fueled with kerosene have broad application prospects in unmanned aviation vehicles. The knock phenomenon of kerosene in SI engines is a huge challenge, leading to a much lower power output than gasoline engines. In this context, the combustion characteristics of kerosene blending with hydrogen are analyzed numerically regarding the working conditions of an SI engine. First, the ignition delay time of a kerosene/hydrogen mixture is estimated for temperatures of 600–1000 K and pressures of 15–35 bar using the Tay mechanism. The effects of hydrogen addition are evaluated with a ratio of 0–0.4. The sensitivities of the main reactions that affect the ignition delay time are discussed. Then, the laminar flame speed is predicted using the HYCHEM-SK mechanism, and the effects of hydrogen addition on the net reaction rates of the main reactions are analyzed. The results indicate that the ignition delay time is shortened and the laminar flame speed is increased as the hydrogen addition ratio rises. Meanwhile, the ignition delay time decreases except for the NTC range, and the laminar flame speed increases evidently as the temperature rises. In addition, the ignition delay time decreases obviously as the pressure increases with a temperature greater than 750 K. However, the laminar flame speed declines at 600 K and 800 K, while an opposite trend exhibits at 1000 K as the pressure rises. The laminar flame speed increases by 23.85–24.82%, while the ignition delay time only decreases by 4.02–3.59% at 1000 K as the hydrogen addition ratio rises from 0 to 0.4, which will be beneficial for knock suppression. [ABSTRACT FROM AUTHOR]

In this study, utilization of a bio-based fuel in a turbojet engine is comprehensively monitored with adapting various useful indicators for the scope of the study based on thermodynamic principles. In this regard, extensive energy and exergy, thermoecologic, environmental, enviroeconomic and sustainability analyses are performed for both the turbojet engines fueled by jet kerosene and fueled by a bio-based fuel. As per the main findings, the mass stream of combustion emissions is measured to be 4.547 kg s−1, when the engine is powered by biofuel. The specific fuel consumption and specific thrust are determined as 0.13 kg kN−1 s−1 and 147.81 kNs kg−1 for jet kerosene-powered case, while they are calculated as 0.15 kg kN−1 s−1 and 148.23 kNs kg−1 for biofuel-powered case. If biofuel is selected over jet-kerosene fuel, it is observed that the engine has better energy efficiency performance by 18.18%. The engine's environmental effect factor value is found as 4.88 for jet-kerosene usage condition, while it is found to be 4.93 for biofuel utilization case. The overall emitted CO2 emissions is measured as 336,672 kg-CO2 year−1 for jet-kerosene usage condition, while it is estimated as 222,012 kg-CO2 year−1 for the biofuel utilization case. Also, as far as biofuel is chosen as alternative to jet-kerosene, the environmental damage cost stream, namely the enviroeconomic parameter of the engine, falls from 59,254.27 US$ year−1 to 39,074.11 US$ year−1. It is observed that sustainable efficiency factor and exergetic sustainability index outputs of the components of air compressor are the same for jet-kerosene and biofuel utilization cases, which are 8.31 and 7.31, respectively. [ABSTRACT FROM AUTHOR]

The mixing state of the fuel determines whether the scramjet combustor can work with high performance. The flow field structure and mixing characteristics of the supersonic combustor are studied by using large eddy simulation. The combustor is equipped with struts and uses gaseous kerosene as fuel. The particularity of the strut is that a row of holes in the tail edge of the strut can inject oxygen into the combustor to enhance mixing. First, the flow field structure without oxygen supplementation is studied, and the evolution rule of the flow direction vortex is analyzed. Second, the mixing performance of the fuel and oxidant is evaluated using mixing efficiency. The mixing performance of the combustor under different fuel injection momentum flux ratios is discussed. Then, the differences in the mixing characteristics of the combustor with and without supplemental oxygen are compared. The influence of different fuel/oxygen momentum flux ratio combinations on mixing performance and flow field characteristics is considered. The effect of oxygen supplementation on the fuel diffusion volume is given at last. The results of this work show that oxygen supplementation can change the flow field characteristics and fuel transportation, and significantly improve the mixing performance. [ABSTRACT FROM AUTHOR]

The annular scram combustor is a popular configuration for combined engines owing to its compatibility with both turbines and rockets and its ability to withstand high flame temperatures. However, a significant challenge associated with this design is the large width of the combustor, which can make it difficult to establish and stabilize flames at supersonic speeds. To address this issue, under the conditions of Tt = 1680 K, Pt = 1.64 MPa, and Ma = 2.7 at the inlet of the combustor, some experimental studies have been carried out in a fan-shaped large width-to-height supersonic combustor fueled with liquid kerosene based on single-strut and multi-strut. The ignition and development of the flame were captured and analyzed using a high-speed camera, and the flame establishment process was compared across different equivalence ratios. The results revealed that the ignition process with a single-strut injection method consisted of a central-flame establishment stage with a weak flame strength. The flame establishment process under the multi-strut condition involved two stages: a central-flame establishment stage of downstream propagation and a cross-flame stage of countercurrent propagation. The multi-strut injection method improved the ignition performance of the combustor by increasing the fuel diffusion range and reducing the airflow speed. The central flame was further classified into four states based on ignition characteristics at different equivalence ratios: diffusion-weak state, diffusion-strong state, contraction-weak state, and contraction-strong state. The central-flame state had a significant effect on the flame-crossing process. The ignition performance in the multi-struts combustor was high when the central-flame was in a diffusion-strong state. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are well-known hazardous substances; nevertheless, research on their exposure and health concerns associated with kerosene fuel emissions is limited. In this study, PAH (combined gaseous and particle phase) monitoring was carried out in the kitchen and living room in selected households. Personal exposure and cooking time monitoring were also carried out, simultaneously. The study's findings revealed that BaP, BA, BbF, and Nap were the most prevalent PAHs in both the summer and winter seasons, regardless of urban or rural households. The estimated values of average incremental lifetime cancer risks were found to be greater than the USEPA level, i.e., 1 × 10–6, in both urban and rural households, regardless of seasonal fluctuation. In both seasons, the non-carcinogenic risk for developmental and reproductive effects was higher in rural women than in urban women, and in case of developmental risk it showed greater than unity (rural: 1.11 and urban 1.03) in the winter season. On the other hand, Monte Carlo simulation model revealed that concentrations of PAHs (97.1% and 97.5%) and exposure duration (51.7% and 56.7%) were the most sensitive factors contributed for health risk estimations for urban and rural area in both seasons, respectively. Furthermore, the results clearly showed that women who were using kerosene for cooking were at a greater risk of acquiring both carcinogenic and non-carcinogenic health consequences from PAH exposure from kerosene cookstoves. It was recommended that they should utilize clean fuel, either by using LPG under the PMUY scheme or by using electricity/solar power to reduce health risks for better health. [ABSTRACT FROM AUTHOR]

For high-Mach-number incoming flow circumstances, a rotating detonation ramjet engine configuration is proposed in this research. By installing supporting blocks at the rear of the combustor, this configuration achieves continuous rotating detonation operation. Based on the Comparison of the flow structures obtained from the engine configuration with and without the supporting block before and after detonation ignition respectively, we obtain the intrinsic mechanism of detonation wave's propagation and re-initiation under the action of the supporting block. The supporting block creates a deflagration wave that is almost stationary before detonation ignition. In the detonation-ignited state, the deflagration wave is continually formed and traveling upstream under the influence of the supporting block, which is analogous to the periodical before detonation ignition of a transverse wave structure. The dynamic deflagration wave will cause the incomplete reactants behind the detonation wave to burn as the intensity of the detonation wave decreases. As a result, the incident shock wave is transformed into a Mach stem to achieve the re-initiation of the detonation wave. • The continuous spin detonation with kerosene as fuel is realized at flight Mach number M = 6. • Flow characteristics in the before and after detonation ignition states with and without supporting blocks are compared. • The supporting block may effectively contribute to maintaining the continuous propagation of the detonation wave. • The detonation wave's mechanism of propagation and re-initiation is examined under the influence of the supporting block. [ABSTRACT FROM AUTHOR]

Piston engines fueled by kerosene have a strong application prospect in special vehicles and small aircrafts, but the low amount of octane in kerosene fuel causes its knock combustion phenomenon to be particularly serious. A knock will deteriorate the power and economy of the engine and will damage the engine in serious cases. Therefore, knocking is the key problem with kerosene engines. We propose a knock-prediction system for kerosene engines based on in-cylinder pressure signals. Firstly, the intrinsic mode function (IMF) caused by knock resonance is extracted from the in-cylinder pressure signal via empirical mode decomposition (EMD) and a time–frequency domain analysis. A time-domain statistical analysis (TDSA) combined with a principal component analysis (PCA) is used to extract features from the IMF. Finally, the data collected from the test bench are trained by a support vector machine to obtain the knock-prediction model. Compared with other technical combinations for training, the proposed scheme achieved more accurate results in knock prediction. Considering the working characteristics of kerosene engines, a slight knock can increase the power of a kerosene engine. Therefore, some incorrectly predicted cycles (slight-knock cycles) do not affect the normal operation of the engine. [ABSTRACT FROM AUTHOR]

The ignition process in a thin strut equipped supersonic combustor fueled with liquid kerosene was observed to deepen the understanding of the ignition characteristics. A large number of experiments were carried out under the conditions of Tt=1,680 K , Pt=1.87 MPa , and Ma=2.8. The combustion establishment process and the flame characteristics were captured and reproduced by a high speed camera. Results show that the flame is first established near the igniter flame in the lower half of the combustor under the action of the recirculation zone and oxygen supplement at the end of the strut. Then, the flame spreads to the main flow of the combustor. The ignition process under different equivalence ratios was compared and studied. The results indicate that the ignition delay time and the flame distribution of the ignition process are affected by the equivalence ratio. At the same time, it was found that there are two modes in the flame establishment process, namely, the upstream propagation mode and the downstream propagation mode. The flame propagation speeds in different directions under these two propagation modes are different. The results presented in this paper are valuable for the future optimization of ignition performance in a scramjet combustor using kerosene fuel injection. [ABSTRACT FROM AUTHOR]

Shock wave focusing is considered a new type of initiation method that does not require external ignition devices. For this method, understanding the shock wave/flame interaction accurately is one of the critical issues for revealing the ignition and triggering mechanisms during shock wave focusing processes. In this study, numerical simulations were carried out to investigate the detailed flow field evolution of the focusing process with kerosene as fuel. Two detonation initiation modes were found during the shock wave focusing processes, which were the direct initiation mode and the reflected shock wave collision initiation mode, respectively. At the detonation wave propagation stage, the primary detonation wave decouples and fails to propagate out of the cavity. The multiple initiation phenomenon occurs in the cavity, and it dominated detonation waves to propagate outside of the cavity to accomplish one thermal cycle. There is no positive correlation between jet temperature and detonation wave propagation velocity. When the jet temperature is low, the detonation wave velocity dominated by the multiple initiation mode is the fastest. The analysis of the shock wave focusing process under different jet velocities showed that when the jet velocity was lower than 2 Ma, the decoupling of the primary detonation wave failed to induce multiple detonation waves. Driven by the vortex in the semicircular cavity, the flame is almost stationary, which means the failure of the detonation wave propagation process. [ABSTRACT FROM AUTHOR]

A series of impact fuel tank experiments are carried out through the ballistic impact method. The ignition abilities of Bi2O3-reinforced PTFE/Al reactive material, metal aluminum, and inert metal steel are compared and analyzed, and the ignition mode of kerosene is explored when PTFE/Al/Bi2O3 impacts the fuel tank at different velocities. The results offer that PTFE/Al/Bi2O3 reactive material has outstanding ignition ability, and the order for ignition ability is PTFE/Al/Bi2O3 reactive material, metal aluminum, and inert metal steel. The kerosene content of the fuel tank has a significant impact on the ignition effect. The ignition effect of PTFE/Al/Bi2O3 reactive material impacting the fuel tank filled with 50% kerosene is weaker than that impacting the full tank. Under different impact velocities, PTFE/Al/Bi2O3 reactive materials display diverse ignition modes for kerosene: kerosene is directly ignited by the flame in the reverse reaction zone under low-velocity conditions, while high-temperature-activated reactive fragments are the ignition heat source of high-velocity conditions. [ABSTRACT FROM AUTHOR]

Hybrid rocket engines are a green alternative to solid rocket motors and may represent a low-cost alternative to kerosene fueled rockets, while granting performance and control features similar to that of typical storable liquid rocket engines. In this work, the design of a three-stage hybrid launcher is optimized by means of a coupled procedure: an evolutionary algorithm optimizes the engine design, whereas an indirect optimization method optimizes the corresponding ascent trajectory. The trajectory integration also provides the vertical emission profiles required for the evaluation of the environmental impact of the launch. The propellants are a paraffin-based wax and liquid oxygen. The vehicle is launched from the ground and uses an electric turbo pump feed system. The initial mass is given (5000 kg) and the insertion of the payload into a 600-km circular, and polar orbit is considered as a reference mission. Clusters of similar hybrid rocket engines, with only few differences, are employed in all stages to reduce the development and operational costs of the launcher. Optimization is carried out with the aim of maximizing the payload mass and then minimizing the overall environmental impact of the launch. The results show that satisfactory performance is achievable also considering rocket polluting emissions: the carbon footprint of the launch can be reduced by one fourth at the cost of a 5-kg payload mass reduction. [ABSTRACT FROM AUTHOR]

This study explored the applications of liquid hydrogen (LH2) in aerospace projects, followed by an investigation into the efficiency of ramjets, scramjets, and turbojets for hypersonic flight and the impact of grey, blue, and green hydrogen as an alternative to JP-7 and JP-8 (kerosene fuel). The advantage of LH2 as a propellant in the space sector has emerged from the relatively high energy density of hydrogen per unit volume, enabling it to store more energy compared to conventional fuels. Hydrogen also has the potential to decarbonise space flight as combustion of LH2 fuel produces zero carbon emissions. However, hydrogen is commonly found in hydrocarbons and water and thus it needs to be extracted from these molecular compounds before use. Only by considering the entire lifecycle of LH2 including the production phase can its sustainability be understood. The results of this study compared the predicted Life Cycle Assessment (LCA) emissions of the production of LH2 using grey, blue, and green hydrogen for 2030 with conventional fuel (JP-7 and JP-8) and revealed that the total carbon emissions over the lifecycle of LH2 were greater than kerosene-derived fuels. [ABSTRACT FROM AUTHOR]

This research is focused on analysing the thermodynamic performance outcomes of the ammonia-fueled turbofan engine. The assessment contains exergy sustainability, economic aspects, environmental impact, and energy and exergy analysis at take-off, climb-out, climb and cruise levels. The required mathematical modelling for thermodynamic analysis of the turbofan engine was performed with Engineering Equation Solver (EES) software. Then it was calculated how much improvement could be achieved in the amount of emissions that occur in the case of using ammonia and kerosene. It was determined that the combustion chamber (CC) has the greatest improvement potential of the turbofan. The maximum productivity lack rate (83.87 %) was determined in the CC at the cruise level, minimum productivity lack rate (0.72 %) was found to be the LPC at the same level. During the take-off level, the turbofan engine had the highest energetic and exergetic fuel costs, reaching 37138.38 $/h and 34195.78 $/h, respectively. The highest specific fuel consumption (85.602 kg/kN.h), thermal efficiency (53.78 %) and thrust efficiency (40.29 %) of the turbofan engine using ammonia as fuel carried out at the take-off level. Eventually, the maximum carbon dioxide emission reduction was calculated as 43.84 tonCO 2 /h when compared to kerosene fuel. • Thermodynamic performance outputs for ammonia-fueled turbofan were evaluated. • SFC, thrust and thrust power were conducted for all altitude levels. • Exergy sustainability and economic analyses for each component were performed. • Environmental analyses for each component were investigated. • CO 2 Emission outputs were compared with the kerosene fuel. [ABSTRACT FROM AUTHOR]