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The presented study focuses on a numerical simulation of the transport phenomena inside a solid oxide fuel cell anode. The classical mathematical model leads to a notable discrepancy between measured and predicted overpotentials. One of the possible reasons is the assumption of the constant values of electrochemical reaction charge transfer coefficients. A modified formulation of the problem includes data-driven correction of reaction charge transfer coefficients in the electrochemical reaction model. Here we show a dedicated computational scheme in which an artificial neural network updates the charge transfer coefficients depending on the operational conditions and the available datasets. The neural network was trained on twelve experimental data points of an anode's polarization curve obtained from the literature. The training set contained data for the anode operating in two different temperatures - 800 °C and 900 °C. The test set contained additional six data points for an anode operating at 1000 °C. Charge transfer coefficients were proposed by the Artificial Neural Network as a functional relation of the temperature and withdrawn current. The results of the predictions are juxtaposed with the experimental data from the literature. It was shown that an Artificial Neural Network could improve an electrochemical reaction model in Solid Oxide Fuel Cell modeling.

The mechanical properties of magnesium alloy AZ31 were investigated experimentally with visco-plastic self-consistent modeling. Tension, compression and plane strain compression (PSC) tests were performed along 3 directions of a hot rolled plate, and the material parameters input in the model were fitted with the uniaxial stress-strain curves. The critical resolved shear stress (CRSS) for tension twinning was modeled with a modified Voce hardening law first decreasing, and then increasing with strain, that could reproduce better the flow stress for twin-predominant deformation. Such CRSS evolution may better model twin nucleation, propagation and growth. Firstly simulations were carried out assuming latent hardening coefficients for slip by other slip systems equal to self-hardening. Then different heterogeneous latent hardening were used, whose values were based on dislocation dynamics simulations from the literature. This study shows that equal self and latent hardening can reproduce the stress strain curves and plastic anisotropy as well as heterogeneous mode on mode latent hardening. Discrepancies between simulations and experimental results from PSC are explained by an under-estimation of twinning for some PSC strain paths.

Energy pile is a kind of economic and efficient geothermal utilization technology that the ground heat exchanger (GHE) used in ground source heat pump (GSHP) is embedded into building pile foundation to realize heat exchange with surrounding soil. Adding phase change material (PCM) into the energy pile can not only reduce the temperature variation and thermal deformation range of energy pile, but also improve its energy storage and heat transfer performance. In this work, phase change concrete energy pile (PCCEP) is proposed by using PCM as a part of backfill material of energy pile. A three-dimensional numerical model is developed to find the influences of thermal properties of PCCEP on its thermo-mechanical behaviour. According to the model, the influences of thermal conductivity, phase change latent heat (PCLE) and phase change temperature (PCT) on the thermal performance and mechanical characteristics of PCCEP are numerically investigated. It can be seen that for improving heat transfer performance of PCCEP, the thermal conductivity should be increased, but from the perspective of reducing change of pile displacement, axial force and side friction resistance, the thermal conductivity should be reduced. Under heat release mode, lower PCT and larger PCLE contribute to the improvement of thermal performance of PCCEP, and accordingly the rise range of pile temperature, pile displacement change and pile thermal stress can all be reduced. The experimental validation on the model shows that the simulation values of pile wall middle temperature(PWMT) and pile top displacement are agreed well with the corresponding experimental results, the real-time relative error of PWMT and pile top displacement are respectively within 5.1 and 12%.

Refereed/Peer-reviewed Objectives: The aim of this systematic review was to critically review and synthesise the findings from primary studies on pitching mechanics and performance of healthy adult baseball pitchers. Design: Systematic review with meta-analysis. Methods: Eight English- and Japanese-language databases were systematically searched from inception to 22nd July 2022. Results: In total, 29 descriptive biomechanical studies were included. Overall study quality was moderate. In subgroup analyses, professional pitchers showed significantly higher stride length, peak shoulder internal rotation velocity, peak shoulder proximal force and ball velocity compared to collegiate pitchers. Conversely, collegiate pitchers were found to have significantly higher peak pelvis rotation velocity. Conclusions: Available normative data suggested potentially heterogeneous pitching mechanics and performance between professional and collegiate pitchers. However, the findings in this review should be interpreted cautiously. Since statistical heterogeneity was significant within most data sets, more detailed subgroup analyses are required. Additionally, more high-quality studies utilising measurement systems with established reliability are required to obtain accurate data in baseball pitching mechanics and performance.

In this research, experimental investigation of the coefficient of the heat transfer has been conducted for a set of rectangular fins with different fin height, 0.27, 0.47 and 0.67 m at air velocity test points of 1.1, 1.3, 1.5, 1.7 and 2 m/s, to meet the Reynolds number (Re). Thirty samples from the two cases with changing fin positions were studied to verify the thermal performance of the system. The study was conducted based on the cross-sectional diameter of 21167, 25016, 28864, 32713, and 38486. Total heat flux in all tubes has been settled as 26.3, 58, and 88.7 W/m2. The experimental results showed that the temperature difference between the surface of the block and flowing air increases with increasing Reynolds number for all heat flow states.

Blade elemental design in aerofoil in wind turbine will increase the effectiveness of power generation. Low velocity blades less than 10 m/sec considered for the design optimization in CFD. Present study is a comparison of NACA 0012, NACA4412 and used in low velocity vertical axis wind turbine. The purpose of these research was to analyse the effect on aerodynamic efficiency of the VAWT aerodynamic (maximum rotor energy coefficient) of two NACA-series 4-digit aerodynamic wings, maximum air-foil thickness and maximum camber, and the two variants in parameters on the performance. Angle of increment 0°, 5°, 10°, 15° and velocity variants input from 5, 5.5, 6, 6.5, 7, 7.5, 8 m/s. The pressure distributions at all the relevance have been observed in all the parametric variables. Aerodynamic performance analysis of all air foils with the ANSYS Fluent software was carried out. Included in different angles of approach are also the lift coefficients and drag coefficients. Optimum angles of attack were determined for each profile according to simulations. Final comparison made for both blades with optimal deviations discussed.

The development of electronic devices in the last quarter of the last century brought about a revolution in the electronics industry. Continuous miniaturization and continued operation cause these devices to heat up, which leads to a decrease in their efficiency or damage to their components and that heat can reduce the efficiency of these devices and their life span in addition to the waste of energy, so providing an integrated and efficient cooling system has become an important part of the design of these devices. In this paper, a numerical study was carried out to increase the enhancement in the coefficient of heat transfer of a mini-channel heatsink. The new shape of a mini-channel (converge-diverge) was proposed and compared with the rectangular (straight) channel using pure water and (Fe3o4 and Ag-water) nanofluids as a coolant. In numerical analysis, the Comsol Multiphysics program was used to perform simulation and solved the three-dimensional fluid and heat transfer problem in a mini channel. A CFD module in Comsol Multiphysics is based upon the finite element method with a Galerkin approach to solving the partial differential equations governing. The base temperature, Nusselt Number, friction factor, and thermal resistance have been studied about channel arrangement, with Reynold’s number varieties from (200–1000) and Concentration volume ranges are used (0% – 0.075%). The minichannel heatsink is exposed to a constant heatflux (180 KW/m2) at the bottom. The numerical results indicate that nanofluid and (converge-diverge)mini-channel can increase the heat sink's hydrothermal performance and (Ag- H2O) nanofluid displays superior heat transfer performance than Fe3o4 nanofluid as enhancement in nusselt number reached 43.27% at volume concentration 0.075%.

Here within the article, the consequences of Hall as well as slip taking place on the peristaltic stream of a Jeffrey solution all the way through a permeable middling within an inclined 2D strait below the extensive wavelength estimation are explored, nearby outline explanations are attained meant for the axial swiftness as well as the axial heaviness gradient’s. The possessions of a variety of up-and-coming constraints lying on the propelling distinctiveness are conversed by way of the charts.

Abrasive flow jet machining (ASJM) is modern manufacturing technique which uses comparatively low-pressure abrasive flow jet for machining various machined surfaces like holes, channels and intricate shapes which is not possible from conventional machining processes. The effect of abrasive particle concentration on the impacting slurry velocity on the surface was examined in the present CFD simulation, resulting in target surface erosion. To predict the impact velocity of abrasive particles hitting the surface, a 2D CFD model was used. The depth of machined surface, surface irregularity and surface removal rate at normal incidence mainly depend on the KE of particle, impact angle, etc. in line with previously published research work on highly pressurised air and water driven abrasive jet. In the present work CFD simulation is performed to predict the effect of solid particle concentration on the impacting slurry jet velocity at the target surface and also turbulence kinetic energy near the surface is studied. As per the CFD results the simulation model predictions the velocity of impacting particle goes on decreasing due to internal frictional resistance between solid and liquid phase and it shows scope of further parametric analysis in this area.

The hydrodynamics and mixing during the nonaxisymmetry impingement of a micro-droplet and a sessile droplet of the same fluid are investigated by many-body dissipative particle dynamics (MDPD) simulation. In this work, the range of the impingement angle (θi) between the impinging droplet and the sessile droplet is 0°–60° and the contact angle is set as 45° or 124°. The droplets impingement and mixing behavior is analyzed based on the droplet internal flow field, the concentration distribution and the time scale of the decay of the kinetic energy of the impinging droplet. The dimensionless total mixing time (τm) is calculated by a modified mixing function. With the Weber number (We) ranging from 5.65 to 22.7 and the Ohnesorge number (Oh) ranging from 0.136 to 0.214, we find τm hardly changes with We and Oh. Whereas, θi and surface wettability are found to have a significant effect on τm. We find that θi has no clear effect on τm on a hydrophobic surface, while on the hydrophilic surface, τm increase with the θi. Thus, reducing the impinging angle is a valid method to shorten the τm.

Most finite element models of small arms focus on an idealized barrel, typically one with a perfectly straight bore centerline. Using five different experimentally measured bore centerlines, this investigation analyzes the effect centerline nonlinearity has on projectile exit conditions. This includes the effect of rotating a centerline through several orientations. Modeled using Abaqus/Explicit, this dynamic analysis simulates a single firing cycle for each centerline. Projectile jump is calculated for each model as a measure of the effects of warped centerlines. The warped centerlines have a small effect on barrel dynamics.

Artificial aeration system for aquaculture ponds becomes essential to meet the oxygen requirement posed by the aquatic species. The performance of an aerator is generally measured in terms of standard aeration efficiency (SAE), which is significantly affected by the different geometric and dynamic parameters of the aerator. Therefore, to enhance the aeration performance of an aerator, these parameters need to be optimized. In the present study, a perforated pooled circular stepped cascade (PPCSC) aerator was developed, and the geometric and dynamic parameters of the developed aerator were optimized using the hybrid ANN-PSO technique for maximizing its aeration efficiency. The geometric parameters include consecutive step width ratio (Wi-1/Wi) and the perforation diameter to the bottom-most radius ratio (d/Rb), whereas the dynamic parameter includes the water flow rate (Q). A 3–6-1 ANN model coupled with particle swarm optimization (PSO) approach was used to obtain the optimum values of geometric and dynamic parameters corresponding to the maximum SAE. The optimal values of the consecutive step width ratio (Wi-1/Wi), the perforation diameter to the bottom-most radius ratio (d/Rb), and the water flow rate (Q) for maximizing the SAE were found to be 1.15, 0.002 7 and 0.016 7 m3/s, respectively. The cross-validation results showed a deviation of 3.07 % between the predicted and experimental SAE values, thus confirming the adequacy of the proposed hybrid ANN-PSO technique.

An effective mass transfer intensification method was proposed by embedding different triangular obstacles to improve the gas–liquid mass transfer efficiency in microchannel. The influences of triangle obstacles configuration, obstacle interval and gas flow rate on the volumetric mass transfer coefficient, pressure drop and energy consumption were investigated experimentally. The enhancement factor was used to quantify the mass transfer enhancement effect of triangle obstacles. It was found that the isosceles or equilateral triangle obstacles are superior to the rectangular obstacles. The maximum enhancement factor of equilateral triangle obstacles was 2.35. Considering comprehensively mass transfer enhancement and energy consumption, the isosceles triangle obstacle showed the best performance, its maximum enhancement factor was 2.1, while the maximum pressure drop increased only 0.41 kPa (22%) compared to the microchannel without obstacles. Furthermore, a micro-particle image velocimetry (micro-PIV) was utilized to observe the flow field distribution and evolution, in order to understand and analyze the enhancement mechanism. The micro-PIV measurement indicated that the obstacle structure could induce the formation of vortex, which promotes convective mass transfer and thins the flow boundary layer, accordingly, the gas–liquid mass transfer efficiency is remarkably improved. This study can provide theoretical guidance and support for the design and optimization of microchannel with triangular obstacles.

In contrast to the concurrent mixer-settler, the interaction between the mixing and settling chambers have to be taken into account in the simulation of the countercurrent mixer-settler, and no work has been reported for this equipment. In this work, a three-phase flow model based on the Eulerian multiphase model, coupled with a sliding mesh model is proposed for a countercurrent mixer-settler. Based on this, the dispersed phase distribution, flow pattern, and pressure distribution are investigated, which can help to fill the gap in the operation mechanism. In addition, the velocity vector distribution at the phase port shows an intriguing phenomenon that two types of vectors with opposite directions are distributed on the left and right sides of the same plane, which indicates that the material exchange in the mixing and settling chambers is simultaneous. Analysis of this variation at this location by a fast Fourier transform (FFT) method reveals that it is mainly influenced by the mixing chamber and is consistent with the main period of the outlet flow fluctuations. Therefore, by monitoring the fluctuation of the outlet flow and then analyzing it by the FFT method, the state of the whole tank can be determined, which makes it promising for the design of control systems for countercurrent mixer-settlers.

In research of the characteristics of the cavity evolution, the pressure, and the liquid spurt in hydrodynamic ram, the experiment of the high-velocity fragment impacting the water-filled container had been conducted. The relationships between the above three characteristics have been researched. The evolution of the cavity can be divided into three processes according to its shape characteristics. The first liquid spurt occurred in Process Ⅱ and the rest of it occurred in Process Ⅲ. The duration of the second liquid spurt is longer than the first liquid spurt. When the impact velocity of the fragment is less than 996 m/s, the velocity of the second liquid spurt is the highest. When the velocity of the fragment is greater than 996 m/s, the velocity of the first liquid spurt is the highest. The maximum velocities of the first and second liquid spurt are 111 m/s and 94 m/s respectively. The pressure fluctuated sharply in Processes Ⅰ and Ⅲ. The maximum peak pressures in the shock and the cavity oscillation phases are 15.51 MPa and 7.96 MPa respectively. The time interval of the two adjacent pressure pulses increases with the increase of the fragment velocity.

The focus of this paper is on the measurement and calculation model of void fraction for the vertical upward co-current air–water slug flow in a circular tube of 15 mm inner diameter. High-speed photography and optical probes were utilized, with water superficial velocity ranging from 0.089–0.65 m∙s–1 and gas superficial velocity ranging from 0.049–0.65 m∙s–1. A new void fraction model based on the local parameters was proposed, disposing the slug flow as a combination of Taylor bubbles and liquid slugs. In the Taylor bubble region, correction factors of liquid film thickness Cδ and nose shape CZ* were proposed to calculate αTB. In the liquid slug region, the radial void fraction distribution profiles were obtained to calculate αLS, by employing the image processing technique based on supervised machine learning. Results showed that the void fraction proportion in Taylor bubbles occupied crucial contribution to the overall void fraction. Multiple types of void fraction predictive correlations were assessed using the present data. The performance of the Schmidt model was optimal, while some models for slug flow performed not outstanding. Additionally, a predictive correlation was correlated between the central local void fraction and the cross-sectional averaged void fraction, as a straightforward form of the void fraction calculation model. The predictive correlation showed a good agreement with the present experimental data, as well as the data of Olerni et al., indicating that the new model was effective and applicable under the slug flow conditions.

The damage effects of fluid-filled submunition payload impacted by the kinetic kill vehicle (KKV) are investigated by simulations and ground-based experiments. Numerical simulations showed that the damage level and number of submunitions were significantly influenced by the diameter of the KKV compared with its length. Based on that, a high velocity penetrator formed by shaped charge explosion was used to simulate the direct hit experiment of a KKV impacting submunition payload. Experimental results demonstrated that the damage modes of submunitions mainly included the slight damage, perforation and total smash, showing a good agreement with the simulations. To understand the multiple damage modes of submunitions, the damage behavior of the submunitions in direct hit process were analyzed based on the AUTODYN-3D code. Numerical results presented that increased KKV diameter can increase the crater diameter and expand the damage volume, which will achieve a higher direct hit lethality. Further analysis indicated that there were other mechanical behaviors can enhance the damage to submunitions not lying in the KKV flight path, such as secondary debris kill, neighboring submunitions collision with each other, and high-speed fluid injection effect.

A quasi-isentropic study on the process of driving a cylinder with aluminized explosives was carried out to examine the influence of the aluminum (Al) reaction rate on cylinder expansion and the physical parameters of the detonation products. Based on the proposed quasi-isentropic hypothesis and relevant isentropic theories, the characteristic lines of aluminized explosives driving a cylinder were analyzed, and a quasi-isentropic model was established. This model includes the variation of the cylinder wall velocity and the physical parameters of the detonation products with the Al reaction degree. Using previously reported experimental results, the quasi-isentropic model was verified to be applicative and accurate. This model was used to calculate the physical parameters for cylinder experiments with aluminized cyclotrimethylenetrinitramine explosives with 15.0 % and 30.0 % Al content. The results show that this quasi-isentropic model can be used not only to calculate the cylinder expansion rule or Al reaction degree, but also to calculate the physical parameters of the detonation products in the process of cylinder expansion. For explosives with 15.0 % and 30.0 % Al, 24.3 % and 18.5 % of the Al was found to have reacted at 33.9 μs and 34.0 μs, respectively. The difference in Al content results in different reaction intensity, occurrence time, and duration of two forms of reaction (diffusion and kinetic) between the Al powder and the detonation products; the post-detonation burning reaction between the Al powder and the detonation products prolongs the positive pressure action time, resulting in a continuous rise in temperature after detonation.

In this work, a generalized unsteady magnetohydrodynamic transport of a rate type fluid near an unbounded upright plate is analyzed under Newtonian heating and non-uniform velocity conditions. The vertical plate is suspended in a porous medium and is encountering the radiation effects. Three different fractional models for Maxwell fluid are established by using the modern definitions of Atangana–Baleanu, Caputo–Fabrizio, and Caputo fractional operators. Triple fractional analysis is conducted to reach out to the solutions of consequent flow and energy equations. Laplace transform and Stehfest’s numerical algorithm are jointly applied to solve each fractional model. Shear stress and heat transfer rate are measured at the solid–fluid interface in the form of skin friction coefficient and Nusselt number respectively. The physical significance of associated parameters in velocity and energy boundary layers is investigated and graphs are provided to discuss the relevant physical arguments. A tabular analysis is performed to demonstrate the influence of physical parameters on shear stress and heat transfer rate. An empirical comparison between fractional and classical solutions indicates that fractional operators provide a better explanation of the physical features of the model. It is also analyzed that for Newtonian heating and non-uniform velocity conditions, the Atangana–Baleanu fractional operator is the finest fractional model to describe the memory effect of velocity and energy distribution. The velocity of a Maxwell fluid is always higher for constant velocity condition as compared to the ramped velocity condition. Furthermore, the heat transfer rate declines for increasing values of the fractional parameter α and a minimum value is witnessed for the classical model but, it follows an inverse trend when the radiation parameter R d increases.

This manuscript presents the comprehensive study of thickness stretching effects on the free vibration, static stability and bending of multilayer functionally graded (FG) carbon nanotubes reinforced composite (CNTRC) nanoplates. The nanoscale and microstructure influences are considered through a modified nonlocal strain gradient continuum model. Based on power-law functions, four different patterns of CNTs distribution are considered in this analysis, a uniform distribution UD, FG-V CNTRC, FG-X CNTRC, and FG-O CNTRC. A 3D kinematic shear deformation theory is proposed to include the stretching influence, which is neglected in classical theories. Hamilton’s principle is applied to derive the governing equations of motion and associated boundary conditions. Analytical solutions are developed based on Galerkin method to solve the governing equilibrium equations based on the generalized higher-order shear deformation theory and the nonlocal strain gradient theory and get the static bending, buckling loads, and natural frequencies of nanoplates. Verification with previous works is presented. A detailed parametric analysis is carried out to highlight the impact of thickness stretching, length scale parameter (nonlocal), material scale parameter (gradient), CNTs distribution pattern, geometry of the plate, various boundary conditions and the total number of layers on the stresses, deformation, critical buckling loads and vibration frequencies. Many new results are also reported in the current study, which will serve as a benchmark for future research.

The research of LEFP (linear explosive forming projectile) is of great value to the development of new warhead due to its excellent performance. To further improve the damage ability of the shaped charge warhead, a special shell overhanging structure was designed to increase the charge based on the traditional spherical charge, in which case the crushing energy of LEFP could be guaranteed. LS-DYNA was used to simulate different charge structures obtained by changing the number of detonation points, the length of shell platform, the radius of curvature and the thickness of liner. The RSM (response surface model) between the molding parameters of LEFP and the structural parameters of charge was established. Based on RSM model, the structure of shaped charge was optimized by using multi-objective genetic algorithm. Meanwhile, the formation process of jet was analyzed by pulsed X-ray photography. The results show that the velocity, length-diameter ratio and specific kinetic energy of the LEFP were closely related to the structural parameters of the shaped charge. After the optimization of charge structure, the forming effect and penetration ability of LEPP had been significantly improved. The experimental data of jet velocity and length were consistent with the numerical results, which verifies the reliability of the numerical results.

This paper reports on analysis of an experimental study that aimed to determine the apparent gas permeability in cracked concrete. There is a lack of research on this topic in the international literature, due to the difficulty of performing reliable experimental testing for gas permeability. The principal interest of this work is to present new and reliable experimental results. Analytical functions between the evolution of the apparent crack permeability and the apparent crack opening are also proposed. These functions appear to be relevant in consideration of Poiseuille theory.

The gas–liquid–solid mini fluidized bed (GLSMFB) combines the advantages of fluidized bed and micro-reactor, and meets the requirements for safety and efficiency of green development of process industry. However, there are few studies on its flow performance and no studies on its mass and heat transfer performance. In this paper, the characteristics of gas–liquid mass transfer in a GLSMFB were studied in order to provide basic guidance for the study of GLSMFB reaction performance and application. Using CO2 absorption by NaOH as the model process, the gas–liquid mass transfer performance of GLSMFB was investigated. The results show that the liquid volumetric mass transfer coefficient and the gas–liquid interfacial area both increase with the increase of the superficial gas velocity within the experimental parameter range under the same given superficial liquid velocity. At the same ratio of superficial gas to liquid velocity, the liquid volumetric mass transfer coefficient increases with the increase of the superficial liquid velocity. Fluidized solid particles strengthen the liquid mass transfer process, and the liquid volumetric mass transfer coefficient is about 13% higher than that of gas–liquid mini bubble column.

The objective of the paper was to compare values of the muzzle brake efficiency coefficient for a rifle with active or inactive automatics systems. Special laboratory stand designed for investigating the recoil process was used. The motion of the rifle was detected by the use of the laser interferometer and the optical camera. The recoil velocity time courses were determined by smoothing and differentiation of experimental position records. The results of the experiments indicated that in the case of an active automatics system two values of the recoil velocity can be used for calculation of the energetic efficiency coefficient: the maximum recoil velocity and the final recoil velocity at the end of the automatics action cycle. The values of the coefficient, calculated using these two values of the recoil velocity, distinctly differ. However, it was shown that their values indicate the same relation between the efficiency of various muzzle brakes. The value of the efficiency coefficient, determined on the basis of the final recoil velocity value, is practically the same as that determined on the basis of the final recoil velocity value for the rifle with an inactive automatics system.

With the increase of high-power electrical components in modern ships, especially fully electric ships with electric propulsion drive (EPD), the cooling of EPD electrical components has become particularly important. Providing optimal configurations for heat sinks with high thermal efficiency plays an essential role in this regard. A new technique for improving the efficiency of heat sinks is the utilization of perforated fins. This study examined the effects of perforation geometry (shape and size) on laminar airflow flow and heat transfer characteristics over a perforated plate-fin heat sink. Three-dimensional simulations were conducted using the finite-volume scheme based on the SIMPLE algorithm. In this research, the effects of perforation shape and size on various parameters, e.g., total drag force, average Nusselt number, perforated fin efficiency (PFE), heat transfer performance enhancement (HTPE), and fin optimization factor (η) were evaluated. The results confirmed that at a specific heat transfer surface area for perforated fins, the highest efficiency is achieved by circular perforations. In contrast, the square perforations due to geometric similarity to rectangular fins could reach the maximum size. Consequently, fins with square perforations could achieve the most optimal configuration. Also, results showed that for a constant perforations size, change in perforations shape improves HTPE, PFE, and η by more than 40%, 45%, and 110%, respectively. Also, by modifying perforations size for a specified shape, an increment of more than 35%, 40%, and 150% is observed in HTPE, PFE, and η, respectively.

The problem of two phase bio-convective nano fluid flow past a vertical stretching flat surface in presence of volume fraction of the dust particles has been investigated. Governing partial differential equations of the problem for both fluid and dust phases are transformed into ordinary differential equations using suitable similarity transformations. The resulting non-linear differential equations are solved numerically using MATLAB built-in bvp4c solver scheme. The velocity, temperature of fluid motion and concentration of micro-organisms are presented graphically for various flow parameters. Coefficient of local skin friction, local Nusselt number and local density number of the micro-organisms are calculated and presented in tables for various parameters.

Granular matter can exhibit solid or liquid behavior, which contains complex physical mechanisms. In this work, we experimentally investigated the structural relaxation and avalanche dynamics of particle piles under vertical vibration. The influence of vibration parameters on the avalanche process was studied. The morphological features of avalanches were recorded and classified using high-speed camera. The effects of vibration parameters and particle properties on the relaxation mode are obtained. It is found that the evolution of particle pile height with time can be described by an exponential decay function. The relaxation rate and avalanche characteristics of four types of particles with different sizes are discussed. At the same acceleration level, for two larger particles, a smaller amplitude (A = 0.025 mm) leads to a faster relaxation rate, while for two smaller particles, a large amplitude (A = 0.500 mm) leads to a faster relaxation rate. The analogy powder surface tension is introduced to address the cohesion and flowability evolution of particles under vibration.

The self-excited stick-slip oscillations of oilwell drillstrings are attributed to the nonlinear interaction between the drill-bit and the rock formation. Development of more accurate models will lead to improved predictions allowing more potential for successful suppression of the drillstring vibrations, thus reducing damage to the drilling system, prevention of expensive failures and increased output from the oilwell. In this paper, the effect of the transition from static friction to Coulomb friction on modelling of stick-slip phenomenon of oil well drillstring is investigated through an analysis of the so called ‘decay factor’. Based on a distributed-lumped parameter model (DLPM) of the drilling system, the governing equations of motion for the system are obtained. By using different values of decay factor (low, high and medium), the stick-slip vibrations of the drillstring are validated against published data from full-scale drillstrings. The results from the simulation show that lowering the decay factor increases the critical speed and thus reduces the propensity for stick slip motion. However, a reduction in the decay factor also has the effect of inducing worse stick-slip motion once the critical speed has been reached. The results indicate the wider impact of both correct modelling of the decay factor, but also the importance of correct characterisation of the mud viscosity and drill/well contact for more accurate selection of drilling parameters in the field.

Non-blade-order flow disturbances, also referred to as pre-stall disturbances or tip flow unsteadiness, are closely related with compressor instabilities. The present work provides a comprehensive investigation on multi-scale nature of non-blade-order disturbances and the underlying flow physics in axial compressors. By applying full-annulus Unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations, along with space-time correlation and spatial Fourier decomposition, to the disturbed pressure, the propagating feature of the non-blade-order disturbances is obtained. Further, a bridge between non-blade-order disturbances and the evolution of unsteady vortex has been set up. The results show that non-blade-order disturbances, featured as short-length-scale (35 modes across annulus), first appear as the occurrence of tip leakage vortex fluctuation, while the compressor still operates far from stall. Leading-edge radial vortex appears at near stall condition, and its movement induces a circumferential propagating disturbance overlaying on the one induced by oscillating tip leakage vortex. The interaction of the short-scale disturbances with a low-amplitude long-scale (of circumference) disturbance is observed, which results in disturbances with multiple scales of consecutive spatial modes, along with multiple frequency peaks in spectra. The compressor falls into stall as the circumferential nonuniform scattering of the leading-edge vortexes occurs. The densely- and sparsely-scattered leading-edge radial vortexes induce a high-amplitude long-scale (of circumference) disturbance, i.e. stall disturbance.

Coiled tubing (CT) drilling technology offers significant advantages in terms of cost and efficiency for exploitations of unconventional oil and gas resources. However, the development of CT drilling technology is restricted by cuttings accumulation in the wellbore due to non-rotation of the drill string and limited circulating capacity. Cuttings cleaning becomes more difficult with the wall resistance of pipe-wellbore annulus on the cutting transport. Accurate description of particle transport process in the pipe-wellbore annulus is, therefore, important for improving the wellbore cleanliness. In this study, high-speed camera is used to record and analyze the settling process of particles in the transparent annulus filled with power-law fluids. A total of 540 tests were carried out, involving dimensionless diameters of 0.10–0.95 and particle Reynolds Numbers of 0.01–12.97, revealing the effect of the dimensionless diameter and particle Reynolds number on the annulus wall effect, and the wall factor model with an average relative error of 2.75% was established. In addition, a dimensionless parameter, Archimedes number, independent of the settling velocity, was introduced to establish an explicit model of the settling velocity of spherical particles in the vertical annulus, with the average relative error of 7.89%. Finally, a calculation example was provided to show how to use the explicit model of settling velocity in annulus. The results of this study are expected to provide guidance for field engineers to improve the wellbore cleanliness of coiled tubing drilling.

In current guidelines, the free air blast loads (overpressure and impulse) are determined by spherical charges, although most of ordnance devices are more nearly cylindrical than spherical in geometry. This may result in a great underestimation of blast loads in the near field and lead to an unsafe design. However, there is still a lack of systematic quantitative analysis of the blast loads generated from cylindrical charges. In this study, a numerical model is developed by using the hydrocode AUTODYN to investigate the influences of aspect ratio and orientation on the free air blast loads generated from center-initiated cylindrical charges. This is done by examining the pressure contours, the peak overpressures and impulses for various aspect ratios ranged from 1 to 8 and arbitrary orientation monitored along every azimuth angle with an interval of 5°. To characterize the distribution patterns of blast loads, three regions, i.e., the axial region, the vertex region and the radial region are identified, and the propagation of blast waves in each region is analyzed in detail. The complexity of blast loads of cylindrical charges is found to result from the bridge wave and its interaction with primary waves. Several empirical formulas are presented based on curve-fitting the numerical data, including the orientation where the maximum peak overpressure emerges, the critical scaled distance beyond which the charge shape effect could be neglected and blast loads with varied aspect ratio in arbitrary orientation, all of which are useful for blast-resistant design.

Liquid–solid fluidized beds (LSFB) modeling validation is crucial for establishing design rules and monitoring tools. However, it generally relies on comparing global variables, which overlook dynamic features that influence reaction outputs. This work aims to implement time series analysis tools to compare Radioactive Particle Tracking data with a simulation consisting of Computational Fluid Dynamics coupled with Discrete-Element Method. Experiments have been performed in a pilot-scale LSFB of calcium alginate spheres fluidized with a calcium chloride solution. The Diks’ test indicates that the simulation can capture the LSFB behavior. It also allows diagnosing flow regime transitions from the simulation. Trends of solid dispersion coefficients and mixing times predicted by the simulation are in good agreement with the experiments.

Fischer-Tropsch (F-T) synthesis is an important route to achieve the clean fuel production. The performance of gas–liquid separation equipment involving in the progressive condensation and separation of light and heavy hydrocarbons in the oil-gas products has become a bottleneck restricting the smooth operation of the F-T process. In order to remove the bottleneck, a gas–liquid vortex separator with simple structure, low pressure drop and big separation capacity was designed to achieve the efficient separation between gas and droplets for a long period. The RSM (Reynolds Stress Model) and DPM (Discrete Phase Method) are employed to simulate the flow characteristics and liquid distribution in the separator. The results show that the separation efficiency is influenced by the flow field and liquid phase concentration in the annular zone. The transverse vortex at the top of spiral arm entrains the droplets with small diameter into the upper annular zone. The entrained droplets rotate upward at an angle of about 37.4°. The screw pitch between neighbor liquid threads is about 0.3 m. There is a top liquid ring in the top of annular zone, where the higher is the liquid phase concentration, the lower is the separation efficiency. It is found that by changing the operating condition and the annular zone height the vortex can be strengthened but not enlarged by the inlet velocity. The screw pitch is not affected by both inlet velocity and annular zone height. The liquid phase concentration in the top liquid ring decreases with both the increases of inlet velocity and annular zone height. The total pressure drop is almost not affected by the annular zone height but is obviously affected by the inlet velocity. When the height of annular zone is more than 940 mm, the separation efficiency is not changed. Therefore, the annular zone height of 940 mm is thought to be the most economical design.

High Explosive Anti-Tank (HEAT) warheads and ammunitions are frequently produced by explosive casting inside an axis-symmetric mold with an inverted conical geometry in the basis. In order to prevent manufacturing defects, the solidification process must be controlled. In this study, a dimensionless solidification model has been proposed to investigate the heat transfer considering the natural convection inside the liquid explosive and the numerical simulations were performed by using COMSOL Multiphysics and Modeling Software, employing trinitrotoluene (TNT) thermophysical properties. The effect of three different boundary conditions on the top of the mold have been evaluated: convection, adiabatic and isothermal. It has been observed that solidification process was faster for convection case and slower for isothermal case, while an intermediary total solidification time value was found for adiabatic case. Moreover, liquid explosive was completely surrounded by solid explosive during the solidification process for convection case and also for adiabatic case through the end of the process. Otherwise, it was not observed for isothermal case. The natural convection effects promoted a vortex inside the liquid explosive, accelerating the heat transfer process. It has been concluded that isothermal mold top boundary condition should be preferred to prevent manufacturing defects, avoiding high thermal stress.

We all know that heat exchanger is one of the equipment to transfer the heat between the fluids. Heat will transfer from one side of fluid to another side of fluid. In this project we use counter flow heat exchanger. In this heat exchanger one kind of fluid will come from one side and another kind of fluid will come from another side. Both fluids will be sending inside to the tube in opposite direction. Here we are using two medium one is hot fluid and another one is APISN (American Petrol Institution of Super Natural) with B grade oil. Inside of apparatus we are using copper tube, to enhance the heat transfer. Because that copper is having higher thermal conductivity (385 W/m K). When we compared to the carbon steel (19 W/m K), copper is having more thermal conductivity. The reason for choosing copper tube is not only higher thermal conductivity; it's also having properties like corrosion resistance, max allows able stress and internal pressure. Hot fluid will be send through the way of inside of the copper tube. Over the copper tube will send APISN oil, both will be send in an opposite manner. In a setup of counter flow heat exchanger, we put two holes with some dimension. When the fluid goes inside of the tube we insert the digital thermo-meter to note down the temperature of both inlet and outlet. After taking all reading we will evaluate the counter flow heat exchanger with term of efficiency.

Experimental and numerical studies are carried out to validate the potential of opposing Plasma Synthetic Jet (PSJ) for drag reduction for a hemisphere. Firstly, flow field changes of opposing PSJ are analyzed by comparing the experimental schlieren images and simulation results in a supersonic free stream of Mach number 3. As PSJ is a kind of unsteady pulsed jet, the shock standoff distance increases initially and then decreases under the control of PSJ, which corresponds to the change of the strength of PSJ. Accordingly, the amount of drag reduction of the hemisphere increases initially and then decreases. It is found that there is a short period of “drag rise” during the formation of PSJ before the drag reduction, which is induced by the generation of normal shock waves and the area difference of the cavity wall of PSJ Actuator (PSJA). Secondly, the effects of five parameters, including exit diameter, discharge energy of PSJA, Mach number, static pressure of incoming flow and angle of attack, on drag reduction of opposing PSJ were studied in detail by using numerical method. It is found that the Maximum Pressure Ratio (MPR) has a significant impact on the average drag reduction for a configuration-determined PSJA. For the configuration selected in this study, the flow field of opposing PSJ shows typical Short Penetration Mode (SPM) in a control cycle of PSJ when the MPR is less than 0.89. However, the flow field shows typical Long Penetration Mode (LPM) at some time when the MPR is bigger than 0.89. Relatively better drag reduction is achieved in this case.

Enhancing damping characteristic is one of the effective methods to solve the instability problem of the rotor system. The three-dimensional numerical analysis model of scallop damper seal was established, and the effects of inlet pressures, preswirl ratios, rotational speeds, interlaced angles and seal cavity depths on the rotordynamic characteristics of scallop damper seal were studied based on dynamic mesh method and multi-frequencies elliptic whirling model. Results show that the direct stiffness of the scallop damper seal increases with decreasing inlet pressure and increasing rotational speed and cavity depth. When the seal cavity is interlaced by a certain angle, which shows positive direct stiffness. The effective damping of the scallop damper seal increases with the increasing inlet pressure, the decreasing preswirl ratio and the rotational speed and cavity depth. There exists an optimal interlaced angle to maximize the effective damping and the system stability. The leakage of the scallop damper seal is significantly reduced with decreasing inlet pressure. The preswirl will reduce the leakage flowrate, and the rotational speed has a slight effect on the leakage performance. The leakage of the scallop damper seal decreases with increasing seal cavity depth.

The supply of species gases and removal of liquid water in a PEM fuel cell are performed through gas flow channels. Therefore, optimising the flow channel configurations is critical for maximising performance of fuel cells. In this paper, the ANSYS PEM Fuel Cell Module is used to simulate a PEM fuel cell with an active area of 100 cm2 and four different flow channel configurations: single-channel serpentine, two-channel serpentine, three-channel serpentine, and parallel channel with headers under two set of different operating conditions. Under both sets of operating conditions, the simulation results indicated that 3-channel serpentine configuration has the best performance due to uniform distribution of species gases over the catalyst layer. It was concluded from the simulation results that the pressure-drop along the 3-channel serpentine configuration is less compared to other serpentine channel configurations, which will require less power for the blowing in of the species gases. The results obtained from simulation under more optimal operating conditions (set 2) used by Hwang’s URFC, predicted increase in the performance of all the four channel configurations compared to the set 1 operating conditions due to higher cell temperature and stichometry of inlet gases. Under set 2 operating conditions, the values of pressure drop across all the channel configurations have increased substantially due to higher flow rates of inlet gases.

Slugging represents one of the major regimes in fluidization, which occurs in small diameter beds with large bed height-to-diameter ratio or in large diameter beds with internals that resemble multiple small diameter fluidized beds. Slug types include round-nosed slug, wall slug and square-nosed slug. Studies of the slugs have been mainly focused on round-nosed or wall slugs known as half slug, typically occurring in Geldart group A particle fluidization. The square-nosed slug typically occurring for Geldart group D particles appears to be regarded as simple in its structure. The Electrical Capacitance Volume Tomography (ECVT) imaging of the square-nosed slugging phenomena conducted in this study reveals otherwise. That is the structure of the square-nosed slug is, in fact, complex, particularly with respect to its dynamic variation in fluidization. More broadly, this study examines experimentally the hydrodynamic characteristics of the square-nosed fluidization regime. Specifically, simultaneous measurements from multiple ECVT sensors provide non-invasive, continuous, 3-dimensional imaging of the entire flow region of the slugging bed and hence enabling the dynamic characterization of the evolution of the slugs. The analysis of the 3D images reconstructed for real-time gas–solid volume fraction profile of the slugging fluidized bed indicates that there are three different zones, namely, the bottom fluidization zone, the gas slug zone, and the solid slug zone, co-existing in the bed. The three zones present different hydrodynamic characteristics during the slug evolution. It is found that varying the gas velocity of the slugging bed mainly varies the maximum length of the gas slug zone, while it only has a minor effect on the lengths of the bottom fluidization zone and solid slug zone. It also has an insignificant effect on the solid volume fraction of the three zones.

In many energy and combustion applications, particles experience large temperature gradients, which can affect the coagulation process due to thermophoresis. This study presents a rigorous theory of thermophoretically modified Brownian coagulation in the entire particle size regime. The theoretical derivations are based on the kinetic theory for the free-molecular regime and the harmonic mean method for the transition regime. The coagulation kernels in different size regimes can be expressed as the basic Brownian coagulation kernel times an enhancement factor. The enhancement factor represents the coagulation rate enhancement induced by thermophoresis and is a function of specific dimensionless numbers. Based on the enhancement factor, the thermophoretic enhancement effects on particle coagulation are further analyzed under a wide range of gas and particle conditions. The results show that thermophoretic enhancement effects are ignorable in the free-molecular regime, but need to be considered in the continuum regime and the transition regime. In addition, the enhancement effects increase significantly with increase of gas temperature and temperature gradient while decrease with increase of gas pressure. The present study can improve understanding of thermophoretic effects on Brownian coagulation in the entire size regime and provide a useful tool to calculate the coagulation rates in presence of thermophoresis.

The three-dimensional computational fluid dynamics (3D-CFD) of a pulsating flow applied to the fluid catalytic cracking (FCC) reaction was investigated in the riser of a circulating fluidized bed reactor. The kinetic parameters of the FCC and coke burning reactions for predicting the reactant conversion and product yield percentages were applied. To increase the reactant conversion level and product yield, the effect of the pulsating flow operating parameters was considered using a 2k statistical experimental design with four factors (amplitude, frequency, types of the waveform, and amplitude ratio). The 3D-CFD simulation was successfully validated from the experimental literature data. The frequency and type of the waveform were found to be the significant operating parameters. The expression of the fitted regression model and response surface contour were derived and revealed that the pulsating flow provides a higher reactant conversion level and product yield percentages compared to a non-pulsating or steady flow.

Supercritical water fluidized bed reactor (SCWFBR) is a novel concept for the gasification of coal and biomass to produce hydrogen. In this work, to enhance the mixing in the axial direction, an inclined distributor is introduced to optimize the flow dynamics in SCWFBR with partitioned fluid supply. Through numerical simulations based on the two fluid model (TFM), the effects of the inclined distributor structure and operating parameters on the solid distribution and the residence time are evaluated with the optimal values determined. Numerical results show that, area ratio = 2:1, SCW velocity ratio = 3:1, flow ratio = 3.36:1 and inclination angle = 20 ° are the optimal design in this paper. A predictive correlation of the minimum fluidization velocity for the improved SCWFBR is also proposed based on the numerical data. The average error between the correlation and numerical simulation results is approximately 1.4% which strongly demonstrates its capability. Finally, based on the optimal design, the lab-scale reactor is further scaled up and the studies about two scale-up rules are carried out. Only the cold flow is simulated in this study without considering chemical reaction which would be involved in future work.

In this study, we focused on the effect of the underwater explosion parameters of multi-point array explosion. The shock wave and bubble parameters of aggregate charge, two charges, and four charges were measured through an underwater explosion test, and their influence on the explosion power field of charge quantity and array distance was analyzed. Results show that the multi-shock wave collision of array explosion can be approximated to a linear superposition, and the interaction of delayed shock wave can be deemed as the increase of the shock wave baseline. Shock wave focusing and delayed superposition increase the shock wave peak pressure. Compared with the aggregate charge, the greater the number of array explosion points is, the higher the impulse and the gain of the bubble peak pressure are. At the same array distance, the smaller the charge quantity is, the higher the bubble impulse will be. At the same charge quantity, the smaller the array distance is, the higher the bubble impulse will be. The bubble period decreases gradually with the increase of the charge quantity, but the test orientation has little effect on the bubble period.

Flow field is a crucial factor to influence the stability and surface quality in the electrochemical machining (ECM) of blisks. A four-way flow mode was proposed to eliminate mixing regions of electrolyte at the leading and tailing edges. Two flow field models were described separately in this report: a W-shaped flow mode and a four-way flow mode. The flow field was analyzed through a finite element method. The results showed that, in comparison with the W-shaped flow mode, the distribution of electrolyte flow was more uniformed and the mixed region in the flow channel was improved. The pressure of the leading and tailing edges inlets was optimized, and optimal pressure of 0.6 MPa was determined. In addition, verification experiments were performed, and the results showed that the stability, efficiency, and quality of the profiles of the blisk blade manufactured by ECM were enhanced in the new flow mode.

The lunar surface is a typical vacuum environment, and its harsh heat rejection conditions bring great challenges to the thermal control technology of the exploration mission. In addition to the radiator, the sublimator is recommended as one of the promising options for heat rejection. The sublimator makes use of water to freeze and sublimate in a porous medium, rejecting heat to the vacuum environment. The complex heat and mass transfer process involves many physical phenomena such as the freezing and sublimation phase change of water in the porous medium and the movement of the phase-change interface. In this paper, the visualized ground-based experimental approaches of space sublimation cooling were presented to reveal the moving law of three-phase point and the growth phenomenon of ice-peak and icicle in microchannels under vacuum conditions. The visualized experiments and results prove that the freezing ice is divided into the porous ice-peak and the transparent icicle. As the sublimation progresses, the phase-change interface moves downward steadily, the length of the ice-peak increases, but the icicle decreases. The visualized experiments of space sublimation cooling in the capillary have guiding significance to reveal the sublimation cooling mechanism of water in the sublimator for lunar exploration missions.

In addition to photovoltaic cells, solar power plates, photovoltaic lights, and solar pumping water, solar energy is the primary source of heat from the sun. At the moment, researchers are looking at the use of nanotechnological and solar radiation to increase aeronautical efficiency. In this study, hybrid nanofluid flow linearly passes through a parabolic trough solor collector (PTSC) on the interior of solar aircraft wings to study heat transmission. Solar radiative flow was the term used to describe the heat source. The heat transfer efficiency of the wings is evaluated for several effects, such as a slanted magnetic field, viscous dissipation, play heating, and thermal radiative flow. Entropy generation study was performed on the Prandtl-Eyring hybrid nanofluid (P-EHNF). The Keller box technique was used to solve the predicted energy and momentum equations. As a typical fluid, EG (ethylene glycol) is used to disperse the nanosolid particles, which consist of copper (Cu) and cobalt ferrite (CoFe2O4). A variety of control factors, including velocity, shear stress, and temperature outlines as well as a frictional factor and Nusselt number, are addressed in detail. Thermal radiation amplification and variable thermal conduction parameters appear to increase the efficiency of aircraft wings in terms of thermal transfer. Hybrid nanofluid is superior to conventional nanofluid in terms of heat transmission. Cu-EG has a low thermal efficiency between 3.8% and 4.8% than CoFe2O4-Cu/EG nanofluid.

Small tube irrigation is a new type of micro-irrigation that the emitters were replaced by small tubes. The small tubes of 4 mm diameter were connected to the laterals through the flow stabilizer or directly to the laterals. The discharge formulations and total heads of the system have been driven from the basic formulas of friction losses and other minor losses of the laterals. Based on hydraulic analysis of laterals, the cost function of lateral and pump, the operation cost and the objective function of lateral diameter optimization technique was established. In the study, a typical irrigation system of fruit tree was taken as an example, in which the length of lateral pipe was 100 m, and assuming that the small tube flow range is 10–40L/h, lateral diameter ranges 12–25 mm, and the field slope ranges −20%∼20%. The results showed that the minimum total cost was obtained with a lateral diameter of 13.6 mm at 10 L/h flow rate, for the flow rate of 20L/h, the minimum cost is obtained at the diameter of 13.6 mm for down-slopes and 17.2 for flat land and up-slopes, and for the flow rate of 30L/h and 40L/h the minimum cost is obtained at 17.2 mm diameter for any slopes.

Based on the two-arc profile assumption, the expansion deformation and energy absorption of circular tubes compressed by conical-cylindrical dies were reconsidered. First, the deformation of the two arcs was analyzed independently and an improved model denoted as Model-I was established. Then, by further involving the coupling between the bending moment and membrane forces, a more elaborate model, i.e., Model-II was developed. Afterwards, experiments and simulations were conducted to verify the models, which show that, compared with previous theoretical models, Model-II could not only capture the prominent features of the deformation, but also improve the prediction accuracy of the steady driving force significantly. By means of this model, it was found that the critical semi-conical angle, which makes the driving force minimum, increases with the increase of the friction coefficient, expansion ratio as well as the radius/thickness ratio of the tube. And, the energy dissipation due to stretching is always greater than that of bending, while the friction dissipation can account for the largest proportion at small semi-conical angle or large friction coefficient. At a certain friction and die conditions, the specific energy absorption of expanded tubes can be much higher than that under progressive collapse mode.