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With the aim of enhance the designability of burning surface, star and wagon wheel fuel types are applied extensively in hybrid rocket motors. However, mechanism of nozzle ablation in hybrid rocket motors with these complex fuel types is unclear, and this increases the difficulty of predicting ablation laws and thrust. This paper intends to investigate spatial distribution characteristics of nozzle ablation in the hybrid rocket motor with various fuel types. According to the principle that the grain port area and grain length are equal, tube, star, single-port wagon wheel, and multi-port wagon wheel grains are designed. Numerical models for combustion flow and thermochemical erosion are established, and three-dimensional numerical simulations are conducted. A firing test for nozzle erosion is conducted, and hydroxyl-terminated polybutadiene and 95 % hydrogen peroxide are employed. Errors of throat erosion rate and combustion chamber pressure among simulation results and experimental data are 4 % and 4.25 %, respectively. Calculation results demonstrate that the circumferential distributions of nozzle wall temperature and erosion rate show an obvious correlation with fuel types. The maximum throat erosion rates for star, single-port wagon wheel, and multi-port wagon wheel grains occur at the circumferential position of 0° (star slot, spoke slot, and midpoint of outer edge of wheel hole), while the minimum throat erosion rates locate at the circumferential position of 36° (star root, spoke root, and midline of adjacent wheel holes). The circumferential non-uniformity of throat erosion rate of multi-port wagon wheel grain is the highest. When the grain port area and oxidizer mass flow rate are the same, the throat erosion rate of multi-port wagon wheel grain is the highest, followed by the star grain, and the throat erosion rate of single-port wagon wheel grain is the lowest. • Effect of complex fuel types on spatial characteristics of nozzle erosion is studied. • Firing test of carbon-based nozzle erosion is performed to verify numerical models. • Three-dimensional simulations on erosion in hybrid rocket motors are conducted. • Simulation results agree well with test data. • Ablation mechanism of star, single-port, and multi-port wagon wheel grain is revealed. [ABSTRACT FROM AUTHOR]

The increase in pesticide regulations, diminished pesticide options due to resistance concerns, and narrowing grower profit margins require each application to be optimised to reduce spray drift and enhance coverage. However, alternative strategies outside of increasing droplet size are needed as reductions in pest control have been observed. This research explored the potential of a magnetic-assisted sprayer (MAS) to aid in spray coverage and determine its impact on spray droplet size and velocity. The MAS minimally impacted spray droplet size characteristics across the four nozzle types tested (only five of twenty F-tests were statistically significant) and did not impact average or maximum droplet velocities when measured 51-cm from the nozzle compared to the conventional sprayer. Although statistically, the MAS increased droplet size by only 4.6 and 12.5% in two of 12 parameter instances compared to the conventional sprayer, there were indications it may reduce spray drift potential as the driftable fines (% of individual droplets measured with diameters less than 200 μm) were numerically less across all nozzle types tested. Across the five experiments, an improvement in spray coverage and deposition by the MAS compared to the conventional sprayer was only observed in one treatment from one experiment. Overall, the MAS minimally to negatively impacted the measured coverage and calculated deposition from water-sensitive paper. Future research is needed to measure actual spray drift from a MAS as well as to evaluate other potentially influential variables such as water quality, pesticide active ingredient, and plant species. • Magnetic-assist increased droplet size in 2 of 12 comparisons with a stock sprayer. • Slight drift reduction potential (reduced fines in 1 of 4 comparisons) observed. • Droplet velocity was not altered by a magnetic-assisted sprayer. • Coverage and deposition improved in 1 of 58 treatments compared to a stock sprayer. • Future research should evaluate more spray variables combined with magnetic effect. [ABSTRACT FROM AUTHOR]

The work focuses on the characterization of the flowfield over a truncated linear aerospike by combining theoretical grounds, numerical simulations and experimental tests. The experimental investigations are carried out on a test rig designed at Politecnico di Torino for advanced nozzle testing. Fully three-dimensional CFD analyses are performed on the actual geometry of the experimental nozzle model. At low nozzle pressure ratios (nprs) the analysis combines numerical simulations and experimental testing, which are also used for validating the CFD results. At higher nprs, the flowfield characterization is performed only by three-dimensional CFD analyses. In addition to the validation of the numerical method, the edge effects at different nprs have been observed. [ABSTRACT FROM AUTHOR]

Foliar fungicides are available to suppress Diplodia ear rot (DER), caused by Stenocarpella maydis (Berk.) Sutton and Stenocarpella macrospora (Earle) Sutton) in corn (Zea mays L.), but previous research has indicated these fungicides have limited efficacy against the disease using traditional over‐canopy application methods. In an effort to improve coverage within the canopy and potentially improve disease control of DER, experiments were conducted in 2020, 2021, and 2022 to examine the effect of ground‐driven, in‐canopy fungicide nozzle technology on DER severity and spray coverage on the ear leaf and ear of corn plants. Application methods included over‐canopy nozzles, over‐canopy + drop nozzles, and over‐canopy + 360 Undercover nozzles. Within each application method, treatments consisted of a non‐inoculated control, or were inoculated with a conidial suspension of S. maydis. The fungicides benzovindiflupyr + azoxystrobin + propiconazole and pydiflumetofen + azoxystrobin + propiconazole were applied within each application method to measure efficacy against DER. In all years, neither fungicide product nor application method reduced DER severity. No fungicide applications increased yield compared to the non‐treated control. The addition of drop nozzles or 360 Undercover nozzles to traditional over‐canopy nozzles increased spray coverage on the ear (P < 0.0001) compared to over‐canopy nozzles alone. Plain Language Summary: Experiments conducted in Kentucky from 2020 to 2022 examined the efficacy of fungicide application method and foliar fungicides in controlling Diplodia ear rot (DER) in corn. Over‐canopy nozzles, over‐canopy + drop nozzles, and over‐canopy + 360 Undercover nozzles were tested along with two different labeled fungicides. Results showed that neither fungicide nor application method significantly reduced DER severity or increased yield compared to the non‐treated control. The addition of drop nozzles or 360 Undercover nozzles did enhance spray coverage on the ear compared to over‐canopy nozzles alone. [ABSTRACT FROM AUTHOR]

Taking the large storage tank as the cleaning object, a cleaning robot integrating shoveling, crushing, sweeping and dust-absorbing was developed, and its dust-absorbing system was analyzed and optimized. Firstly, Fluent- EDEM gas-solid coupling was utilized to simulate the dust-absorbing system. By analyzing the fluid distribution and particle trajectory, the internal structure of the dust collection box was optimized to reduce the dust particles entering the fan box. Then, by analyzing the structural parameters of the suction nozzle, the influence of the nozzle shoulder angle, nozzle length, and shoulder height on the dust-absorbing effect was explored, and the parameters were determined, so as to reduce the energy loss and increase the flow rate on both sides of the nozzle. Finally, through the dust suction test, different models of nozzles were tested for dust suction, and the wind speed at the nozzle was measured, and the leakage of dust particles on both sides of the nozzle was significantly reduced after optimization, which verified the reliability of the simulation results and provided a theoretical basis for the design of the sweeping robot. [ABSTRACT FROM AUTHOR]

Aiming at the problem that the ground plant protection machine is difficult to enter for plant protection in the middle and late stages of maize field, this paper designs a UAV centrifugal spraying system for maize plant protection based on centrifugal nozzle and plant protection UAV. A single nozzle parameter test was carried out, and the results showed that the droplet size is related to the liquid supply flow rate and the nozzle speed. According to the optimal biological particle size theory, the nozzle parameters with the liquid supply flow rate of 1000 mL/min and the rotation speed of 14000 r/min are selected to test the droplet distribution characteristics under actual operation conditions, and the droplet size, droplet density, coverage and other important indicators of aviation spraying operations are analyzed. The experimental results show that the flight speed of the UAV significantly affects the droplet distribution in the bottom layer of maize. The droplet coverage and droplet deposition of each sampling layer decrease with the increase of flight speed. When the flight speed is 1.5 m/s, the coefficient of variation of the centrifugal spraying system is the smallest, and the droplet deposition effect is the most uniform. This study can provide a reference for the parameter optimization and correct use of centrifugal plant protection UAV in the middle and late plant protection operations of high-stalk crops such as maize. [ABSTRACT FROM AUTHOR]

This research investigates the process of starting and breakdown of second throat diffuser during high-altitude test of conical nozzle with a high expansion ratio. The subscale experimental setup includes a conical nozzle with an expansion ratio of 53, plus a second throat diffuser with a contraction ratio of 1.85, using compressed air as the working fluid. Numerical simulation has been employed to identify the flow physics during the unsteady process of diffuser startup and breakdown. According to the results, the starting process is divided into three distinct stages. In the first stage, the exhausted flow from the nozzle enters the vacuum chamber, leading to an increase in vacuum chamber pressure. The second stage, corresponding to the period before full flow establishment in the conical nozzle, exhibits a relatively constant slope. In the final stage, associated with the transition from over-expanded to under-expanded states, the slope of the rate of evacuation development descends. Next, the vacuum degradation in termination process has been analyzed, and it has been found to include three stages: high slope, middle slope, and low slope. The flow physics during the start process, similar to the results observed in other conical nozzles, exhibits only a Mach reflection structure. However, during the termination process, the flow physics involve a combination of both structures, including Mach reflection and Cap Shock. The results indicate that during the start, an internal shock only interacts with the separation shock, and no special change occurs in the Mach reflection structure. In contrast, during the termination process, unlike what has been reported in previous studies on conical nozzles, the structure of cap shock waves and restricted shock separation patterns are also observed. Another distinction between the starting and termination processes is related to the pressure distribution in the diffuser wall. The wall pressure at the diffuser inlet during the termination process has been reported to be 90% higher than during the starting process. [ABSTRACT FROM AUTHOR]

Four types of nozzles were tested on large-scale trials with a 40 m2 plot unit size. The Avi Twin 110-01 (80 L ha−1), 110-02 (160 L ha−1), 110-03 (240 L ha−1), and 110-04 (320 L ha−1) symmetric double fan injector nozzles were tested during the 2020/2021 and 2021/2022 growing seasons. This study aimed to evaluate the performance of spray nozzles with regard to deoxynivalenol (DON) accumulation in durum wheat grains. Artificial inoculation with Fusarium spp. was performed after durum heads were protected with fungicide. The percentage of heads covered with fungicide droplets, grain yield, yield-related traits, technological quality parameters, and concentrations of DON were determined. Compared to the control (without fungicide treatment), the Avi Twin 04 nozzle caused a reduction of 45.0% in the DON concentration on average across both growing seasons. This positively corresponded to the percentage of heads covered with fungicide droplets, which was highest when this nozzle was utilized. In both trial years, the DON reduction caused by the 110-04 twin nozzle was higher than that caused by the 110-01 nozzle. Treatment with the 110-04 nozzle more effectively improved the grain yield, 1000-kernel weight, and test weight compared to treatment with the 110-01 nozzle and the untreated control. The differences in technological quality were less pronounced when different spray nozzles were used. [ABSTRACT FROM AUTHOR]

Cryogenic liquid hydrogen offers a promising solution for achieving high-density hydrogen storage and efficient on-site distribution. However, the potential hazards associated with hydrogen leakages necessitate thorough investigations. This research aims to model cryogenic hydrogen release from circular and high aspect ratio (HAR) nozzles tested by Sandia. The test conditions cover reservoir pressures and temperatures corresponding to cryogenic hydrogen storage. The study conducts computational simulations using OpenFOAM to examine hydrogen concentration, temperature fields, mass fraction, and temperature distributions, achieving good agreement with the experimental data. To further explore, the study of velocity variations shows a consistent decay rate with room-temperature jets. The numerical data reveals comparable inverse centreline hydrogen mass fractions (0.254 for HAR and 0.26 for circular) and normalised centreline temperature decay rates (0.031 for HAR and 0.032 for circular). The present computational model holds the potential for further analysis of cryogenic hydrogen in large-scale facilities. • Comprehensive study on cryogenic hydrogen release scenarios. • Consistent hydrogen concentration decay rates for circular and HAR nozzles. • Close alignment with Sandia's experimental data for circular and HAR nozzles. • Temperature profiles closely matching experimental data for both nozzle types. • Velocity profiles indicating variations in mixing and dispersion by pressure changes. [ABSTRACT FROM AUTHOR]

This study proposes a customized industrial nozzle for generating impulsive air jets. It is installed on an automatic machine in which wine caps are stacked and shot consecutively into a rotating cylinder by an air jet. This process is very noisy; hence, this study aimed to investigate possible geometric variations of the nozzle that can reduce the emitted noise. First, the nozzle was tested in a laboratory to measure the air consumptions at different supply pressures. Subsequently, 3D models of the nozzle and its variations were created and used for computational fluid dynamics simulations. Different boundary conditions were set, first to validate the model and compare it with the experimental test results, and then to simulate the real working conditions and determine the geometry that is less noisy while maintaining the velocity peak. Among the various possibilities, shortening the final ducts of the nozzle appears to be the most promising solution. These modified nozzles could be easily added to current machines to provide immediate benefits, and this study represents a promising start for action on other machines in which this type of device is present. [ABSTRACT FROM AUTHOR]

This study focuses on the details of the geometry and dynamics of sidewall vortices observed in supersonic wind tunnels with a rectangular cross section of the nozzle and the test section. The formation of sidewall vortices limits the accuracy of the data measured during wind tunnels' testing due to a reduced area of uniform core flow results. Most of the test data presented in this work are generated using Mie scattering visualization for M = 4 flow, with CO2 seeded up to 7% mole fraction. The Mie scattering results are complemented by data from fast pressure sensor and schlieren visualization. It is shown that the formation of vortices is caused by a transverse pressure gradient realized in the supersonic nozzle due to the gas under-expansion. The vortex external mixing layer is strongly perturbed in time but remains globally geometrically similar with streamwise distance. The vortex-generated dominant flow disturbances are in the frequency range of f = 10–50 kHz, doubling the magnitude of baseline power spectral density. The authors' viewpoint is that sidewall vortex generation is a more generic phenomenon than was thought previously. [ABSTRACT FROM AUTHOR]

In order to define the hydraulic operating parameters of the RC FARM model sprinkler for use in the design of sprinkler irrigation systems, a field evaluation was developed in areas of the Agricultural Engineering Research Institute located in Havana, Cuba. In the evaluation, two sets of nozzles were tested and the procedure that appears in the Cuban Standard NC ISO 8026:2014 was followed. To characterize the performance of the sprinkler, the following indicators were used: Uniformity Coefficient (CU), Statistical Uniformity of Uniformity (CEU), Uniformity of Distribution (UD) and Discharge Efficiency (Ed). The losses produced by evaporation and carryover during the test were evaluated as part of the work. The results show that the sprinkler model RC FARM with nozzle 4, 70 mm + 3, 18 mm is characterized by having a flow of 1697,0 L h-1 and an effective reach radius of 11,28 m while with the nozzle 3,97 mm + 3,18 mm the flow is 1476,0 L h-1 and effective radius of 10,15 m, in both cases for a pressure of 250 kPa. The quality of the water distribution for the evaluated sprinkler is defined as acceptable as having CU values greater than 70%, CEU above 65% and UD and Ed indicators that exceed 55 and 63%, respectively. Evaporation and carryover losses during the test reached values of 11,54% and 10,61%. [ABSTRACT FROM AUTHOR]

Considerable progress has been achieved in recent decades in understanding the phenomena related to the onset of condensation in steam flows, both experimentally and especially numerically. Nevertheless, there is still a certain disagreement between the different numerical models used. Unfortunately, the available experimental validation data are not sufficiently detailed to allow for proper validation of computational fluid dynamics (CFD) simulations. Therefore, this paper presents new experimental data for condensing steam flows, acquired in a supersonic nozzle according to Barschdorff, at the Institute of Thermal Turbomachinery Laboratory (ITSM) at the University of Stuttgart. A steady inlet pressure of approximately 784 mbar was set for three inlet temperatures down to 100.2   ∘ C . Condensation onset is accurately captured across the nozzle, using down to 1 mm spatial resolution for both pneumatic and light spectra measurements. CFD simulations were performed using the commercial solver ANSYS CFX. The droplet diameters are numerically overestimated by approximately a factor of 1.5. Disagreement has been found between original Barschdorff's experiments and measurements at ITSM. However, there is a good agreement in terms of the pressure distribution along the nozzle axis between experimental and numerical results. The reproducibility of the results is excellent. [ABSTRACT FROM AUTHOR]

This paper focuses on investigating ablation characteristics of different nozzle materials in hybrid rocket motors by firing tests and numerical simulations. Hybrid rocket nozzles with different ablation materials are designed and manufactured. Four firing tests with working time of 40 s are conducted, and 90% hydrogen peroxide and polyethylene are adopted. The test results indicate that erosion rates of T705 graphite, whole felt C/C composite, axial rod braided C/C composite, and carbon/ceramic composite are 0.045 mm/s, 0.022 mm/s, 0.03 mm/s, and 0.01 mm/s. Circumferentially uneven ablation is found in the nozzle throat of T705 graphite and C/C composite, and this is mainly due to asymmetric oxidizer injection, asymmetric combustion, and uneven material properties. Transient numerical simulations of 40 s on nozzle thermochemical erosion are carried out, and the regression process of fuel wall and nozzle wall is solved by a dynamic grid technique. The error of average throat erosion rate between simulation results and test results is only 1.82%. The evolution process of nozzle profile and flow field structure are exhibited, and coupling effects between the erosion rate and nozzle profile are obtained. Simulation results show that as the working time increases, protrusions and pits appear on the nozzle inner wall and gradually extend. The temperature of nozzle wall and nozzle erosion rate on the windward side is higher, while they are lower on the leeward side. Nozzle throat erosion rate history is divided into four stages, and time nonlinear characteristics of the throat erosion rate are revealed. • 40 s firing tests of different nozzle materials are conducted. • Ablation properties of graphite, C/C composite and carbon ceramic are obtained. • Transient simulations of 40 s on nozzle thermochemical erosion are performed. • Simulation results agree with test data and evolution of nozzle profile is shown. • Time nonlinear characteristics of nozzle throat erosion rate are revealed. [ABSTRACT FROM AUTHOR]

The development of phase change models applicable to a wide range of temperatures, pressures, and mass flow rates is primarily limited by the metastable or partially stable behaviour of the fluid. Due to this, the fluid does not change phase even after crossing saturation conditions. Most liquid–vapour phase change models have been developed primarily for the cavitation process where the phase change is not sustained, occurs in a very narrow region of space, or occurs under equilibrium conditions. In this paper, the mechanism of phase change is discussed along with the review of three different computational fluid dynamics (CFD)‐based phase change methods available in OpenFOAM, which are used to simulate flashing of steam, in applications related to steam assisted gravity drainage (SAGD) systems. The first method is based on barotropic compressibility (BC) used with the realizable k−ε turbulence model, the second combination is of mass transfer model (MTM) with the realizable k−ε turbulence model, and the third one is based on two fluid (TF) method along with a family of k−ω turbulence models. These methods are tested on a converging–diverging nozzle with pressure driven phase change. It is demonstrated that these methods are not able to adjust their physics to different depressurization rates, do not account for liquid to be in superheated conditions, and have significant discrepancies with experimental results. In the end, better approaches to model this category of phase change are discussed. [ABSTRACT FROM AUTHOR]

This research examines the allowable second throat cross-sectional area of exhaust diffuser in ground tests of a thrust-optimized parabolic nozzle with different expansion ratios. First, theoretical methods used to determine the minimum second throat area and the minimum starting pressure of the exhaust diffuser have been reviewed. Next, the results of small-scale experimental tests with compressed air at diffuser inlet area to second throat area ratios (A d /A st) of 1.6, 1.7, 1.8, 1.85, 1.9, and 2 have been presented. To describe the physical phenomena during the start and breakdown conditions, numerical simulation of the flow has been used. The results reveal that with 11% narrowing of the second throat from area ratio 1.6 to 1.8 at all nozzle expansion ratios (34.7–65), the minimum starting pressure has grown by 7–9%. Examination of the further narrowing of the second throat up to area ratio 1.85 indicates that due to temporary flow choking in the second throat, the starting pressure has grown by up to 40%. Also, at diffuser area ratios 1.9 and above, due to severe flow choking in the second throat, the diffuser never starts. Present examinations show that with a large increase in the diffuser area ratio parameter, the nozzle pressure at which the shock pattern transition occurs in the nozzle does not change significantly. Also, diffuser breakdown pressure in the test of nozzles with different expansion ratios has shown very little dependence on the diffuser area ratio parameter. Our examinations indicate that the maximum permissible area ratio reaches the upper limit of 1.8, which is very different from the values calculated by conventional theoretical methods. Further, in this research, it has been shown that the suitable correction factor in estimating the minimum starting pressure with normal shock method in the second throat has lied within 1.4–1.7. The results indicate that the correction factor has heavily depended on the diffuser area ratio parameter. Nevertheless, this factor falls within a close range using a constant diffuser area ratio in testing of a thrust optimized parabolic nozzle with various expansion ratios. Thus, for a simpler application, the area ratio-dependent mean and maximum correction factors have been introduced which have maximum error of 3.2 and 5.6%, respectively. • Investigating the effect of the second throat cross-section on high-altitude testing performance of parabolic nozzles. • Proposing the new correction factors for estimating the diffuser minimum starting pressure. • The hysteresis in the diffuser performance is increased due to increasing area ratio. • The breakdown and separation mode transition pressures have a weak dependence on the diffuser area ratio. [ABSTRACT FROM AUTHOR]

Base pressure is a crucial component in the measurement of flow parameters in a high-speed aerodynamic flow. In this paper, the microjets impact as a control mechanism is experimentally tested for the nozzles with abrupt expansion at supersonic Mach in an axisymmetric conduit. The flow regulation mechanism is placed at a 90-degree interval in the shape of an orifice of 0.5 mm in radius along the nozzle's exit diameter, which generates jets at sonic Mach numbers. The flow constraints studied are inertia level (Mach number), expansion level (NPR), and the geometric parameters considered are the pipe's length (L/D). These three relevant parameters were selected for design of experiments (DOE). In the management of base pressure, this analysis's primary objective is to evaluate the parameters influencing the flow. The experiments were carried out in two ways: without and with microjets. For the DOE, an L27 orthogonal series, polynomial expression, analysis of variance, and predicted plots were carried out to test the experimental findings. The established prototypes are statistically appropriate and achieved when making precise projections for all the cases. According to the present results, the L/D ratio for a given parameter is the most critical parameter influencing the maximum increase or decrease in the base pressure. [ABSTRACT FROM AUTHOR]

This study presents a combined numerical and experimental investigation of the starting process of a second throat diffuser during ground testing of a thrust-optimized parabolic (TOP). In this investigation, compressed air has been utilized as the operating fluid in a subscale experimental setup. The study examines three scenarios with varying nozzle pressure profile, including two cases of start and one case of un-start. Additionally, this study employs numerical simulations to identify and analyze the physical phenomena that occur at each stage of the start and un-start processes in these cases. The results for the case started at a relatively low nozzle pressure profile (24.5 bar max) indicate that the vacuum generation process during high-altitude testing of TOP nozzles can be broken down into five stages. The first stage involves an increase in pressure within the vacuum chamber during the early moments of the starting process. In the second stage, vacuum generation occurs gradually as the nozzle operates under free shock separation (FSS). This is followed with the reappearance of small fluctuations in the vacuum chamber pressure due to transition from the FSS to restricted shock separation (RSS) flow pattern (third stage). The fourth stage begins with the predominance of the shock separation and recirculation (SSR) flow pattern inside the nozzle, resulting in gradual vacuum generation. This stage terminates upon transformation of the cap shock structure into a regular reflection structure. In the final stage of vacuum generation, the evacuation rate is almost half of the fourth stage. This is attributed to the establishment of expanded and under-expanded conditions, as well as the impingement of the nozzle outflow jet with the wall and the onset of start conditions. Next, the results of vacuum generation have been studied at higher nozzle pressures profile (34 bar max). The results indicate that increasing the nozzle pressure rate not only reduced the starting time by 23%, but also significantly reduced the pressure fluctuations in the evacuation process. In fact, at higher nozzle pressure, the third stage is almost eliminated. In the un-started case, where the nozzle pressure is lower than the minimum starting pressure, fluctuations occur in the vacuum chamber pressure due to the dynamics of the diffuser inlet recirculation bubble and the transition of the nozzle separation pattern from RSS to SSR and vice versa. [ABSTRACT FROM AUTHOR]

Firing test campaigns were carried out on a 200 N thrust-class hybrid rocket engine, using gaseous oxygen as an oxidizer and a paraffin-wax-based fuel. Different fuel grain lengths were adopted to extend the fuel characterization under different operating conditions, and to evaluate rocket performances and internal ballistics in the different configurations. In addition to data collected under a 220 mm propellant grain length, two further test campaigns were carried out considering 130 mm and 70 mm grain lengths. Two different injector types were adopted in the 130 mm configuration; in particular, a showerhead injection system was used with the aim to contain high-amplitude pressure oscillations observed during some firing tests in this engine configuration. Parameters such as the chamber pressure and temperature inside the graphite nozzle, space-averaged fuel regression rate and nozzle throat diameter were measured. The results allowed for the investigation of different issues related to hybrid rockets (e.g., fuel regression rate, engine performance, nozzle ablation under different conditions). The focus was mainly directed to the nozzle heat transfer, through the reconstruction of the convective heat transfer coefficient for different tests in the 70 mm grain length engine configuration. The reconstruction took advantage of the experimental data provided by the nozzle embedded thermocouple. Then, the experimental convective heat transfer coefficient was used to validate the results from some empirical correlations. The results showed significant differences between the experimental convective heat transfer coefficients when considering tests with different oxidizer mass flow rates. Furthermore, the predictions from the empirical correlations proved to be more reliable only in cases characterized by oxidizer-rich conditions. [ABSTRACT FROM AUTHOR]

In order to realize the application of the nasal spray vaccination in the prevention and protection of respiratory infectious diseases, a nasal spray vaccination device is designed in this paper. The device uses a Laval nozzle structure to generate a high-speed airflow that impinges on the vaccine reagent and forms nebulized particles. Through optimizing of the Laval nozzle structure and testing experiments on spray particle size, spray velocity, spray angle and spray rate, a set of parameters which is applicable to actual nasal spray vaccination is obtained. The experimental results show that when the air source pressure is 2 bar, the spray angle is about 15°, the diameter of the spray particles Dv50 is about 17 μm, the volume fraction of particles with diameter smaller than 10um is about 24%, the spray rate is close to 300 μl/s. The vaccine activity tests demonstrate that under these conditions, not only the biological activity of vaccines is guaranteed, but also the delivery efficiency is well assured. [ABSTRACT FROM AUTHOR]

The production of liquid-gas mixtures with desired properties still places high demands on process technology and is usually realized in bubble columns. The physical calculation models used have individual dimensionless factors which, depending on the application, are only valid for small ranges consisting of flow velocity, nozzle geometry and test setup. An iterative but time-consuming design of such dispersion processes is used in industry for producing a liquid-gas mixture according to desired requirements. In the present investigation, we accelerate the necessary design loops by setting up a physical model, which consists of several subsystems that are enriched by dedicated experiments to realize liquid-gas dispersions with low volume fraction and small air bubble diameters in oil. Our approach allows the extraction of individual dimensionless factors from maps of the introduced subsystems. These maps allow for targeted corrective measures of a production process for keeping the quality. The calculation-based approach avoids the need for performing iterative design loops. Overall, this approach supports the controlled generation of liquid-gas mixtures. [Display omitted] • The production of desired liquid-gas mixtures places high demands on process technology. • Avoiding iterative design loops by setting up a physical model. • A dimensional analysis according to Buckingham's Pi Theorem identified. • An evaluation algorithm in which gas bubble sizes of different sizes and shapes are classified. • Calculate and measure the intermediate process points for model validation. [ABSTRACT FROM AUTHOR]

The importance of jet noise for prospective supersonic transport (SST) in takeoff and climb modes dictates the need to develop methods for reducing jet noise and their subsequent validation in large- and full-scale tests. This paper presents the results of Russia's first ground acoustic tests of a rectangular nozzle with a noise suppression system, installed on a subsonic aircraft engine to demonstrate the technology. The authors studied a rectangular beveled nozzle with an ejector and screens—elements of the SST airframe. The test results were compared for three nozzle geometries: a round nozzle corresponding to measurements for the original engine without modifications, a rectangular nozzle without screens, and a rectangular nozzle with screens. It was found that when the rectangular nozzle without screens is used, there two opposite effects occur: noise amplification compared to the round nozzle for angles of observation close to the jet axis, and noise attenuation at angles of observation close to the fan rotation plane. Installing screens increases noise up to 5 dB in the low-frequency region below 150 Hz and reduces noise by 2 dB for frequencies higher than 250 Hz. Estimation of community noise in the EPNL metric showed that this rectangular nozzle with the noise suppression system has the effect of reducing community noise in comparison with the baseline round nozzle. [ABSTRACT FROM AUTHOR]

The experiment aimed to Manufacture a device for checking the nozzles and testing its efficiency and to study the effect of research factors on the studied traits. The device was manufactured locally through using materials available in the Iraqi market. The system is Both Hydraulic and electronic (ISO 5682-1)1 relay on sensors technology and the test platform was built and designed on a movable trolly at the department of Agricultural Machines and Equipment / College of Agricultural Science / University of Baghdad. The design includes the use of mechanical water pump and electrical AC water pump. The design includes a nozzle holder that can accommodate three nozzles per test. The design also consists of spreading wings and stationary wing that can accommodate 50 vessels and 50 ultra-sonic sensors. All that is controlled by a main control unit which consists of three branch modules (each one of them is responsible to collect and analyze data from several sensors on each of the wings. The idea behind the design is to merge between actual spraying and the use of electronic sensors to analyze the size of the sprayed liquid in each of the vessels, the concept of the design is based upon Volumetric distribution of the liquid. The concept of the device was based on using ultra sonic sensors to measure the volumetric distribution of liquids. The experiment aimed to determine the effects of these factors on flow rate, spraying angle, sprayed area, spraying swath, volumetric distribution (CV), and symmetry. The experiment was conducted at the college of Agricultural science, Baghdad University. The results showed that the spraying pressure had a non-significant effect on flow rate. However, increasing the pressure from 3.0 to 5.0 and then to 7.0 bar resulted in flow rates of 1.314, 1.286, and 1.36 l/m, respectively. The status of the nozzle (new or worn) did not significantly affect the flow rate, with new nozzles registering a slightly higher flow rate of 1.327 l/m compared to worn nozzles (1.312 l/m). On the other hand, the type of nozzle had a significant impact on flow rate, with plastic, brass, and steel nozzles registering flow rates of 1.243, 1.422, and 1.29 l/m, respectively. Regarding the spraying angle, the results indicated that the spraying pressure had a significant effect. Increasing the pressure from 3.0 to 5.0 and then to 7.0 bar resulted in spraying angles of 132, 132, and 136 degrees, respectively. The nozzle status significantly affected the spraying angle, with worn nozzles resulting in a higher angle of 137 degrees compared to new nozzles (130 degrees). However, the type of nozzle did not significantly affect the spraying angle. For the sprayed area, the spraying pressure had a significant effect, with higher pressures resulting in larger sprayed areas. Worn nozzles also significantly increased the sprayed area compared to new nozzles. The type of nozzle had a significant impact on the sprayed area, with plastic, brass, and steel nozzles resulting in areas of 70.4, 80.44, and 89.16 cm2, respectively. The experiment proved that nozzles must be tested periodically, otherwise they start to perform beyond the parameters they were designed to perform with. [ABSTRACT FROM AUTHOR]

To effectively solve the problem of high dust concentration during coal cutting and frame shifting in fully mechanized mining faces, based on the theory of gas–solid two-phase flow, a geometric model of a fully mechanized mining face was established by using COMSOL numerical simulation software. Simulations were performed for the movement characteristics of wind flow and the law of dust diffusion. Results show that the air flow at the junction of the working face, the air inlet, the hydraulic support moving area, and the vicinity of the shearer has accelerated movement, and the maximum wind speed zone of about 3 m/s can be formed. Under the influence of wind flow, dust particles above 35 μm settle faster, while dust particles below 35 μm are very vulnerable to the influence of wind flow, and the settling speed is slower. Using a custom experimental platform, the atomization characteristics and wind resistance of a pressure fan nozzle, a supersonic nozzle, and an ultrasonic nozzle were tested, and the nozzle that was suitable for the scheme was selected and applied in the field. Comparing the dust concentration before and after the application of the dust removal scheme at the sampling point, results show that the dust removal efficiency of the proposed scheme exceeds 85%, and the treatment effect is good. [ABSTRACT FROM AUTHOR]

Thrust vectoring is a promising technology that offers the potential for improved maneuverability, control efficiency, and stealth characteristics of aircraft. Optimized nozzle design over a range of operating conditions is one of the most crucial factors for maximum thrust vectoring operation. Our goal was to investigate the optimal design of bypass dual throat nozzle to maximize thrust vectoring. We performed a multi-objective optimization study by varying the nozzle bypass angle, convergence angle, and bypass width to see what impact these parameters had on the performance of the bypass dual throat nozzle. A steady numerical simulation has been performed on 55 different nozzle configurations to compare their thrust vectoring performance and losses. In all simulations, the k- ϵ turbulence model is used to determine the vectoring states of the nozzle. The computational fluid dynamics analysis was followed by a multi-objective optimization process using the Response Surface Methodology within the ModeFrontier software. The testing of the optimized nozzle shapes using ANSYS FLUENT verified the accuracy and reliability of the multi-objective optimization algorithm. These findings suggest that nozzle convergence does not significantly affect thrust vectoring. In contrast, bypass width and bypass angle significantly affected thrust vectoring. [ABSTRACT FROM AUTHOR]

Discharge through nozzles used in gas-based fire protection of data centers may generate noise that causes the performance of hard drives to decay considerably; silent nozzles are employed to limit this harmful effect. This work focuses on proposing an experimental methodology to assess the impact of sound emitted by gaseous jets by comparing various nozzles under several operating conditions, together with relating that impact to design parameters. A setup was developed and repeatability of the experiments was evaluated; standard and silent nozzles were tested regarding the discharge of inert gases and halocarbon compounds. The ability of silent nozzles to contain the emitted noise—generally below the 110 dB reference threshold—was proven effective; a relationship between Reynolds number and peak noise level is suggested to support the reported increase in noise maxima as released flow rate increases. Hard drives with lower speed were the most affected. Spectral analysis was conducted, with sound at the higher frequency range causing performance decay even if lower than the acknowledged threshold. Independence of emitted noise from the selected clean agent was also observed in terms of released volumetric flow rate, yet the denser the fluid, the lower the generated noise under the same released mass flow rate. [ABSTRACT FROM AUTHOR]

Multi-nozzle spraying tools are applied in numerous industrial applications, one of the most common being die-casting. To ensure the quality of a cast product and to avoid production downtimes proper functioning is required, e.g. in terms of spray targeting, mass flow, or reproducibility. To enable regular functional controls of a spraying tool, we have developed a specific measuring principle based on monitoring the spray impact on a heated plate using infrared thermography. In this paper, the performance of the developed measuring principle is examined. The study is performed with a typical spraying tool from foundries, it has nine external mixing airâ€"water nozzles, which are freely adjustable in their orientation. During an injection, the spray impacts a heated plate positioned in front of the spraying tool and creates a wetting pattern that is individual to each spraying tool, like a fingerprint. The recorded cooling pattern can be used to determine the position of the individual spray impact areas, the size of the spray impact areas, and the intensity of the cooling. Based on these parameters, conclusions can be drawn about the functionality of the water-bearing lines and the air-bearing linesâ€"as well as the correct alignment of the individual nozzles. The result shows that the presented measuring principle leads to very high precision and reproducibility of the evaluated parameters. Thus, the developed measuring system enables detailed functional tests of complex spraying tools. [ABSTRACT FROM AUTHOR]

The mixing enhancement and core length reduction of a jet without significant loss of thrust are essential for reducing infrared radiation, mitigating aeroacoustic noise, improving combustion characteristics, and thrust vectoring. The jet mixing can be improved by manipulating the flow behavior. In subsonic and sonic jets, the flow manipulation may be achieved by utilizing nozzles with non-circular geometries that shed vortices of varying size due to their non-uniform azimuth curvatures. Non-uniform vortices generate differential spreading along the nozzle's perimeter, causing axis switching and improving entrainment characteristics. Therefore, the present study examines the effects of two non-circular nozzle exit shapes (elliptic and square) on the mixing augmenting efficacy at subsonic and sonic flow conditions. The circular nozzle is tested for comparison. Both quantitative and qualitative analyses evaluate the efficacy of nozzles with non-circular exit geometries. Among the configurations investigated, the elliptic nozzle is superior in shortening the potential core length and enhancing the jet spread. A maximum reduction of 18.75% in core length with rapid jet decay was accomplished with the elliptic nozzle. The measurement of pressure profiles at different streamwise locations reveals that the spread rate is greater for elliptic and square jets than their circular counterpart. The elliptic jet exhibits the highest spread along the minor-axis direction compared to the major-axis direction. The differential jet spread rate in the elliptical jet causes an early axis-switching––direct evidence of mixing augmentation. Shadowgraph images show the asymmetric pattern of shock cell structures and differential spreading in elliptic and square jets. [ABSTRACT FROM AUTHOR]

This paper introduces experimental and numerical analysis of nozzle ablation in SF6 gas circuit breakers. Ablation and changes in the diameter of a nozzle were measured in the experiments. In addition, an ablation model was developed and simulations of nozzle ablation were carried out. The relationship between geometric changes to the nozzle due to ablation and the injection energy was investigated using both experimental measurements and data predicted by simulation. The predicted values for mass loss and geometric changes to the nozzles tested show similar tendencies to the experimental results. Also, the developed ablation model was applied to the mixture of fluoronitrile and CO2 gas. By predicting flow and pressure changes due to the ablation effect, the interruption performance of gas circuit breakers after repeated testing can be analyzed. [ABSTRACT FROM AUTHOR]

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Summary: The aim of this study is to investigate the radiative protection provided by various fire hose nozzles used by several Fire Rescue Services in France and to propose an experimental set‐up to quantify it. This study combined the use of radiative sources (a radiant panel or a fire inside a standard shipping container) and metrological devices (radiative heat sensors, IR camera and spectrometer) to estimate the radiative attenuation of water sprays used to protect the firefighters against thermal effects which occur during a fire. For all the fire hose nozzles tested in this work, the maximal effective attenuation reaches 75%. For most of them, an increase of the flow rate improves the radiative attenuation. However, this study shows that a similar attenuation can be reached for different flow rates, suggesting that the droplet size diameter and the droplet volume fraction also play a significant role in the efficiency of the provided spray. [ABSTRACT FROM AUTHOR]

Aiming at the problems of the low efficiency of manual pesticide application in the greenhouse, the narrow operating space of plant protection machinery, and the possibility of poisoning the pesticide applicators due to the closed space, a high-pressure atomization spraying equipment for the greenhouse was designed. The spraying equipment adopts two-way communication between PLC and HMI to realize the adjustment of atomization pressure and atomization flow, and the control equipment completes automatic spraying. To determine the best working parameters of the spraying equipment, orthogonal tests were conducted with atomization pressure and atomization nozzle aperture as the test factors and the coefficient of variation of the fog volume distribution as the evaluation index. The optimum combination after parameter optimization was determined to be as follows: atomization pressure of 4 MPa, atomization nozzle aperture of 0.4 mm. The test results under the optimal parameters showed that the spray distribution coefficient of variation was 10.5%, and the uniformity of fog volume distribution was good to meet the requirements of spraying in greenhouses. [ABSTRACT FROM AUTHOR]

• An experiment setup with the function of testing single or multi-nozzles' atomization characteristics was developed. • The atomization characteristic and mechanism of a swirl nozzle for outdoor snow-makers were revealed. • The droplet diameter distribution and SMD variation were explored when twin-nozzles cooperating at different condition. • Droplet diameter variations were explained by the theories of collision and breakup. Swirl nozzles are the core component of outdoor snow-makers for forming snow crystal artificially. A general experiment setup for simulating the atomization process at the working conditions of outdoor snow-makers was developed. Phantom high-speed camera and PW180-B laser particle size analyzer (LPSA) were used to capture the dynamic atomization process and droplet diameter distributions respectively. The atomization characteristics of a single swirl nozzle and that of twin nozzles were tested and analyzed. For single nozzle, Sauter Mean Diameter (SMD) drops rapidly and then goes up gently due to the action of droplets breakup and coalescence. With the increase of the injection pressure, the SMD of the droplets decreases, and the mass flow rate of the nozzles is improved. Moreover, the spray cone angle increases rapidly and keeps a stable value. For twin nozzles, the cooperation of the swirl nozzles obviously reduces the SMDs of the atomization field because it enhances the probability of droplets collision and separation. The SMDs are determined by the cooperative distances and injection pressure. [ABSTRACT FROM AUTHOR]

A highly loaded, aqueous-based zirconium carbide (ZrC) paste was developed for ceramic on-demand extrusion (CODE). Commercial ZrC powder was ball milled to reduce the particle size to ∼1 μm. Paste composition was determined by rheological characterization and observation of printing behavior; the final paste consisted of 46–47 vol% ZrC, 43.5 vol% distilled water, 8.1 vol% dispersant, and 1.6 vol% binder. Rheological characterization of the paste showed a yield stress of ∼8 Pa and shear thinning behavior (ΔG′/Δσ* = −55). The paste was printed using a 610 μm nozzle; a test print showed shape fidelity using the developed paste. A pressureless sintering study was performed; a sintering temperature of 2000°C with a 2-hour hold produced samples of 90 % relative density with 3.8 μm grains, which was consistent with literature. The developed paste, in combination with the pressureless densification results, adds a new, ultra-high temperature material to ceramic extrusion additive manufacturing. [ABSTRACT FROM AUTHOR]

This paper describes an innovative application, driven by an industrial requirement for an alternative welding process to submerged arc welding of header heat exchanger tube nozzles, of an automated friction hydro-pillar processing (FHPP) welding platform (WeldCore©). This was the first successful application of rotary friction welding of heat exchanger tube nozzles to high pressure-headers used in the high-pressure heaters of a boiler on a 609 MW steam turbo-generator unit. The FHPP WeldCore platform allows highly time- and cost-effective welding and repair of high temperature, high pressure power plant using a procedure that was approved in the 2015 ASME Boiler and Pressure Vessel Code, Supplement 3 as Code Case 2832 (WPS qualification for Friction Taper Hydro-Pillar (FTHP) welding). This certification opened the way to using FHPP welding for repair and refurbishment of power generation and high temperature process plant. After completing the welding of 448 nozzles onto each of two HP headers, all welds were found to be defect-free using ultrasonic testing, and test nozzle welds passed the weld qualification procedure required by industry. • 609 MW turbo-generator. • Friction hydro-pillar processing applied to HP Header nozzles. • Cost and time effective compared with Submerged Arc Welding. • 448 nozzles welded defect-free. • In-situ PWHT. [ABSTRACT FROM AUTHOR]

We report on the design and testing of glass nozzles used to produce liquid sheets. The sheet nozzles use a single converging channel chemically etched into glass wafers by standard lithographic methods. Operation in ambient air and vacuum was demonstrated. The measured sheet thickness ranges over one order of magnitude with the smallest thickness of 250 nm and the largest of 2.5 μm. Sheet thickness was shown to be independent of liquid flow rate, and dependent on the nozzle outlet area. Sheet surface roughness was dependent on nozzle surface finish and was on the order of 10 nm for polished nozzles. Electron transmission data is presented for various sheet thicknesses near the MeV mean free path and the charge pair distribution function for D2O is determined from electron scattering data. [ABSTRACT FROM AUTHOR]

This paper presents original research of a model of water–water ejector whose aim is to mix a quantity of water of the return network with the water of the supply network of a central heating system. The water of the supply network at a certain pressure passes through the ejector nozzle, where the pressure energy in the nozzle is converted into kinetic energy, and consequently in the space around the nozzle vacuum gauge pressure is created which enables the absorption of a quantity of water from the network return, which is mixed with the water of the supply network. This water regulates the temperature of the water at the entrance of the central heating radiator. For the model ejector, characteristic equation was written and was analyzed in terms of pressure and mixing coefficient. The analysis was tested using nozzles of different sizes. To analyze the role of the diffuser as a part of the ejector, the ejector characteristics were analyzed without a diffuser. The characteristics of diffuser and non-diffuser ejectors are presented in the same diagram for comparative analysis of the pressure difference and mixing coefficients achieved by the ejector for different ratios f3/fr1. [ABSTRACT FROM AUTHOR]

In this paper, the drying characteristics of Radial Jet Reattachment (RJR) and Slot Jet Reattachment (SJR) nozzles, with an exit angle of +45∘ for the RJR nozzle and +20∘ and +45∘ for the SJR nozzle, were experimentally investigated in drying potato chip samples and apple slices, respectively. Dry basis moisture content of the samples using these innovative nozzles were compared to those of traditional nozzles, based on three criteria: identical air mass flow rate, identical fluid flow power, and identical exerted peak surface pressure. To appraise the performance of each nozzle, the corresponding local heat transfer coefficients generated by innovative and traditional nozzles for all the tests were measured. Subsequently, the average heat transfer coefficients of reattachment nozzles were calculated and compared against those of traditional nozzles. Moreover, the kinetics of color changes and structure analysis of apple slices, due to the drying by SJ and SJR + 20∘ nozzles were studied. The experimental results revealed that the RJR + 45∘ and SJR + 20∘ nozzles yield significantly higher drying rates, as well as significant improvement in average heat transfer coefficients, compared to those of ILJ and SJ nozzles, respectively, on a stationary basis. Besides, impingement drying with SJR + 20∘ nozzle produced dried apple slices with less color deterioration and fewer nutritional losses compared to drying with the SJ nozzle. Therefore, jet reattachment nozzles can provide faster drying rates and keep the nutritional values at a desirable level. [ABSTRACT FROM AUTHOR]

To explore the dustfall effect of combined nozzles used in a fully mechanized mining face, Phase Doppler Interferometry (PDI) system was used to test 6 types of high-efficiency atomizer under 8 MPa. A new nozzle group of nozzles 2#, 3#, and 5# is selected by atomization experiment. The atomization experiment and field application test of the preferred nozzle are performed. The experiment and field application results show that, with the spray pressure of 8 MPa, when the distance in the nozzle group is 200 mm and the angle change is 10 degrees, the atomization effect is the best. Under the optimal parameters, the average dustfall rates of the entire and respirable dust are 81.82% and 79.96%, respectively, which are 23.49% and 20.75% higher than those of the traditional shearer. [ABSTRACT FROM AUTHOR]

Featured Application: A theoretical model that allows analyzing the effects of spray pressure on drop size distribution was devised. The model can be used to predict nozzle spray quality parameters under ordinary working conditions. For spray applications, drop size is the most important feature as it affects all aspects of a phytosanitary treatment: biological efficacy, environmental pollution, and operator safety. In turn, drop size distribution depends on nozzle type, liquid properties, and working pressure. In this research, three nozzles were studied under ordinary working conditions and the effect of pressure on drop size distribution was assessed. The nozzles under test, all from Albuz (France), were an orange hollow cone nozzle ATR 80 (European color code), an air induction flat spray nozzle AVI 11003, and an air induction hollow cone nozzle TVI 8002. The ATR 80 and the TVI 8002 nozzles were tested at four pressure values: 0.3, 0.5, 1.0, and 1.5 MPa; the AVI 11003 nozzle was tested at 0.3 and 0.5 MPa. The drop size measurement technique was based on the liquid immersion method by using a custom-made test bench; spray quality parameters were computed by means of suitable functions written in R language. Results showed that an increase in working pressure caused an increase in drop pulverization regardless of the type of nozzle, and drop pulverization was higher for the turbulence nozzle than for the two air induction nozzles. Based on skewness and kurtosis values, the theoretical gamma distribution was the most adapt to fit the experimental data. The scale parameter showed a decreasing trend with the increase in the pressure, a clear index of higher drop pulverization. [ABSTRACT FROM AUTHOR]

In order to determine the optimal layer height and the maximum height of the ceramic slurry formed by micro-flow extrusion, the five height relations between the nozzle and the deposited filament were analyzed after the filament Hew out of the nozzle for zircona ceramic slurry, the influence mechanism of the height of the nozzle on the pining quality was discussed, and the interlayer compression deformation model was established according to the slurry characteristics. The surface morphology, forming percussion and mechanics properties of the printed samples were measured and characterized by digital microscope scanning, dimension measurement and mechanics test through 3D printing technology tests with different nozzle diameters and different layers, and the correctness of the model was verified. The results show that under the different ratios of the layer height to the nozzle diameter, the printing quality from good to bad is as follows: 0.96, 0.92, 0.86, 1, 1.2. Therefore, a reasonable layer legit setting may reduce the printing defects of ceramic parts, and improve the printing quality, which may provide some theoretical guidance for the selection of processing parameters based on material extrusion-based additive manufacturing. [ABSTRACT FROM AUTHOR]

This investigational analysis exemplifies the design and test of diffuser at compressor inlet and nozzles at condenser outlet and expansion valve outlet in VCR with the help of Rl34a refrigerant. The diffuser with divergence angle of l5°, l7° and the nozzle with convergent angle l5°, l7° are designed for same inlet and outlet diameters. Initially diffusers are tested at compressor inlet diffuser is used with inlet diameter equal to exit tube diameter of evaporator and outlet tube diameter is equal to suction tube diameter of the compressor. Diffuser helps to increases the pressures of the refrigerant before entering the compressor it will be helps to reduces the compression work and achieve higher performance of the vapour compression refrigeration system. Then nozzles are testing at condenser outlet and expansion valve outlet, where as nozzle inlet diameter equal to discharging tube diameter of condenser and outlet diameter equal to inlet diameter of expansion valve. Extra pressure drop in the nozzle helped to accomplish higher performance of the vapour compression refrigeration system. The system is analyze using the Ist and IInd laws of thermodynamics, to resolve the refrigerating effect, the compressor work input, coefficient of performance(COP).. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)