Search

Unstable airflow driven by natural wind forces inside a grass aerial seeding tower is a technical problem that needs to be improved. The authors used FLUENT 2020 R2 to simulate a basic nozzle unit, which is the fundamental component of a grass aerial seeding tower. The interior flow characteristics of the tower were first analyzed. Then, an optimization was undertaken to enhance the internal airflow's uniform stability, taking the cross-sectional inclination angle as the design parameter. The coefficient of variation, uniformity index, and velocity direction index were considered as constraints. The simulation results indicate that, subsequent to traversing the Laval nozzle unit, the grass seeds undergo a considerable acceleration. At an inclination angle of 15°, while ensuring the attainment of desired exit velocities, a commendable balance of uniformity and directional consistency was achieved. [ABSTRACT FROM AUTHOR]

The Laval nozzle is an important component of the supersonic cyclone to achieve the change of gas–liquid two-phase, and the condensation characteristics of the Laval nozzle have an important influence on the separation performance of the supersonic cyclone. In this work, the effect of inlet water vapor mass fraction on the condensation characteristics in the Laval nozzle was investigated using numerical simulation and experimental methods by establishing a three-dimensional numerical model of air-water vapor supersonic condensation flow. The flow field structures in the Laval nozzle under different inlet water vapor mass fractions were investigated, including Mach number, pressure, and temperature and the effects of the inlet water vapor mass fraction on the liquefaction characteristics in the Laval nozzle were investigated. In addition, the droplet distribution in the Laval nozzle were also tested by a particle image velocimetry (PIV) experimental system. The comparison of simulation and experimental results indicates that the numerical model established in this work can effectively describe the real flow situation in the Laval nozzle. The results show that the inlet water vapor mass fraction has a little effect on the flow field structure in the Laval nozzle, and has the significant impact on the water vapor condensation characteristics. With increasing the inlet steam mass fraction from 5 % to 12.5 %, the nucleation rate, droplet number, and separation efficiency in the Laval nozzle increase to 4.05 × 1021 kg−1 s−1, 3.67 × 1014 kg−1, and 79.4 %, respectively, and when further increasing the inlet steam mass fraction to 15 %, these parameters decrease. [ABSTRACT FROM AUTHOR]

The cutting thickness of the flame cutting nozzle mainly depends on the characteristics of the cutting oxygen jet, and in the process of designing and manufacturing a flame cutting nozzle with an ultralarge thickness, it is impossible to carry out multiple experiments to optimize the design due to the difficulty in testing, safety, manufacturing cost, environmental pollution, and other problems. In this paper, the Laval-type cutting oxygen orifice channel was first designed by theoretical calculation, the pressure, velocity, Mach number, and density distribution characteristics of the cutting oxygen jet were investigated by numerical simulation, and the reliability and adaptability of the numerical simulation results were verified by experiments. Then, the numerical simulation comparison and estimation method of jet characteristics with the general-purpose G301-7# nozzle was used to study the cutting oxygen orifice channel of the ultralarge thickness flame cutting nozzle. The results show that under the condition of a 19 mm throat diameter and 10 atm inlet pressure, it was estimated that the length of cutting oxygen flow from the design nozzle can reach 1800 mm and the cutting thickness can reach 2500 mm based on the density value; the length of cutting oxygen flow can reach 2000 mm and the cutting thickness can reach 3800 mm based on the velocity value; the length of cutting oxygen flow can reach 1600 mm according to the value of the oxygen quality fraction; and the cutting thickness can reach 2800 mm based on the oxygen mass fraction content. Finally, trial production of the nozzle design, verification of the cutting test, the nozzle with a cutting thickness of 2500 mm at an oxygen pressure of 7 atm, and the cutting quality were all good.

An impact mill has been developed to produce powders from shavings of refractory metals using the impact grinding method for reuse in electrometallurgy in devices with screw feed, for example, in 3D printers. The proposed device provides high uniformity of grinding with a minimum content of dust fraction and impurity content at low technical and economic costs. The result is achieved using a Laval nozzle, which operates in the supersonic jet formation mode. In the area of the first Mach disk, there are rod fenders arranged in a cascade, and the impact plate is located in the turbulence zone and is equipped with winglets with holes for separating crushed metal. [ABSTRACT FROM AUTHOR]

Supersonic separation technology is a cutting-edge method for efficient dehydration and hydrocarbon removal, yet challenges arise from the intricate flow dynamics within a supersonic nozzle. To address these challenges, a novel cascade drainage structure is proposed in this paper, combining the high swirl intensity of flush-type drainage with the extended drainage section, larger opening area, and reduced flow velocity of cylindrical drainage with oblique openings. Through comprehensive physical modeling and numerical analysis, this design is shown to enhance separation performance and mitigate fluid blockage within the nozzle. Through physical modeling and numerical analysis, we demonstrate its effectiveness in enhancing separation and mitigating fluid blockage. Experimental results confirm the cascade drainage structure's superiority, particularly at an optimal pressure ratio (${R_{np}}$ R np = 1.4). Ethanol vapor removal rate (${\delta _{steam}}$ δ steam ) and dew point drop ($\Delta {T_d}$ Δ T d ) reach 53.94% and 18.32°C, respectively, surpassing alternatives. Maintaining a 2 mm discharge clearance yields an outstanding dry gas ratio of approximately 85%. The findings contribute to advancements in dehydration and hydrocarbon removal processes, showcasing the potential for enhanced performance in supersonic separation technology within a concise framework. [ABSTRACT FROM AUTHOR]

Large resources of thermal and industrial waters at a temperature of 100–150°С can be employed to generate electricity in both a single-circuit thermal cycle with direct usage of natural steam in condensing turbines and a double-circuit cycle with a low-boiling working fluid. Both options require high capital expenditures for their implementation. A new power-generation method on the basis of low-grade heat is to install a full-flow hydro-steam turbine (HST), which utilizes the heat of separated liquid from a geothermal station or the heat of industrial waters, in a single-circuit thermal cycle. Capital expenditures for these units are much lower since special equipment for preparation of the working fluid is not required. The efficiency of a hydro-steam turbine is directly related to the efficiency of its main element, which is the Laval nozzle. Designing this turbine requires reliable data on the performance of a Laval nozzle with a high expansion ratio when it operates on highly subcooled water. Such information can only be obtained experimentally since this region of operation of Laval nozzles has been poorly studied as of yet. To determine the required characteristics of the nozzles, an experimental setup was designed and manufactured with a set of Laval nozzles, including nozzles with different opening angles of the diverging section and nozzles with an oblique cut. The working fluid was water under conditions close to the operating conditions in an HST. The results are presented of the experimental study of Laval nozzles in a wide range of expansion ratios for operation on boiling water. The experiments were performed at different pressures downstream of the nozzle, and their results were compared with previously obtained experimental data. The experimental setup and design features of the nozzle are described. The experimental data on the flow coefficient, velocity coefficient, expansion ratio, initial conditions, nozzle shapes, and size effect, on which the conclusions made are based, have been analyzed. Characteristics have been found that enable us to predict the efficiency of a reaction hydro-steam turbine and properly calculate its output. [ABSTRACT FROM AUTHOR]

The use of a supersonic separator presents a novel approach for separating ammonia (NH3) from hydrogen (H2). Even trace amounts of water (H2O) can significantly influence the condensation characteristics of NH3. This study presents mathematical models for homogeneous NH3 and H2O condensation and heterogeneous NH3–H2O condensation. Through computational analysis, we revealed that the droplet radius and liquid mass fraction of a single condensable gas condensation increased accordingly with increasing inlet condensable gas content. Interactions between the condensation processes of NH3 and H2O were also captured in the simulation. Notably, at 100 ppm H2O content, H2O spontaneously condensed before NH3, serving as a condensation nucleus for NH3, and the heterogeneous condensation of NH3 decreased the rate of its spontaneous condensation. At an inlet H2O content of 50 ppm, the onset of spontaneous NH3 condensation coincided with that of H2O, with H2O having a negligible effect on NH3 condensation. The impact of H2O on NH3 condensation transitioned from minimal to inhibitory and then to facilitative as the content of H2O increased from 25 ppm to 250 ppm. At the nozzle outlet, the liquid mass fraction of NH3 initially decreased from 0.0414 to 0.0352 and then increased to 0.0446.

Unstable airflow driven by natural wind forces inside a grass aerial seeding tower is a technical problem that needs to be improved. The authors used FLUENT 2020 R2 to simulate a basic nozzle unit, which is the fundamental component of a grass aerial seeding tower. The interior flow characteristics of the tower were first analyzed. Then, an optimization was undertaken to enhance the internal airflow’s uniform stability, taking the cross-sectional inclination angle as the design parameter. The coefficient of variation, uniformity index, and velocity direction index were considered as constraints. The simulation results indicate that, subsequent to traversing the Laval nozzle unit, the grass seeds undergo a considerable acceleration. At an inclination angle of 15°, while ensuring the attainment of desired exit velocities, a commendable balance of uniformity and directional consistency was achieved.

Measurement while drilling (MWD) plays an important role in controlling well trajectory, improving drilling efficiency and saving drilling cost. In recent years, a large number of high-temperature wells have appeared, which makes the traditional MWD instruments no longer applicable. So far, no active cooling method has been successfully applied to MWD instruments for high-temperature oil and gas wells. This paper presents a new active cooling method for air drilling by utilizing the throttling and cooling of drilling gas, and the cooling system is designed. An axisymmetric numerical model of internal fluid is established, and different drilling gas flow channel design methods are discussed. The research results indicate that the wall temperature of the cooling section is much higher than the center fluid temperature, but lower than the ambient temperature, and can be used for active cooling of downhole drilling instruments. Compared with other design methods, the supersonic nozzle designed using the Bezier method has better parallelism of the gas in cooling section. The diffusion capability of straight wall diffuser is better than that of curved wall diffuser, and it can withstand greater back pressure. For straight wall diffuser, increasing the throat length and reducing the contraction and expansion angle can improve the diffusion capacity, but they also lead to a longer diffuser.

Transonic planar flows around a circular cylinder are investigated numerically for laminar and turbulent flow conditions with Reynolds numbers of 50 ≤ R e D ≤ 300 and 8890 ≤ R e D ≤ 80,000 and free stream Mach numbers in the range of 0.2 ≤ M a ∞ ≤ 2 . A commercially available CFD tool is used and validated for this purpose. The results show that the flow phenomena occurring can be grouped into eight regimes. Compared to the incompressible flow regimes, several new phenomena can be found. In contrast, at higher M a ∞ of 0.6 ≤ M a ∞ ≤ 0.8 vortices in the wake of the cylinder are suppressed for R e D = 50 . In some cases, M a ∞ = 0.8 and R e D ≥ 300 , λ -shocks are formed in the near cylinder wake. For supersonic M a ∞ , two different phenomena are observed. Beside the well-known oblique and detached shocks, for 50 ≤ R e D ≤ 300 a wake with instabilities is formed downstream of the cylinder. Furthermore, the temporal mean drag coefficient C ¯ D , the Strouhal number S t r , as well as the critical Mach number M a crit are calculated from the simulation results and are interpreted. [ABSTRACT FROM AUTHOR]

The thrust vector control of a rocket engine by disturbing the supersonic flow in its nozzle is used for missile development for various purposes in different countries. Disturbance of the supersonic flow in the jet engine nozzle can be caused by various obstacles on the nozzle wall: solid obstacle, liquid or gas jet, combinations of solid obstacle with injected jets. The simplest and most effective way to create a disturbance is to disturb it by setting a solid cylindrical obstacle on the nozzle wall. The high efficiency is explained by the lack of the working fluid consumption on board the aircraft to create a control force, or its minimum amount necessary to protect the obstacle from the high-temperature oncoming gas flow in the rocket engine nozzle. This paper presents the study results of gas flow simulation with cylindrical obstacle perturbation on the wall of the Laval rocket engine nozzle in its subsonic and supersonic parts. The optimal placement in the nozzle is determined to obtain the maximum lateral control force. As a result of research, it was found that the perturbation of a supersonic flow in a rocket engine nozzle by a cylindrical obstacle has practically the same character when its position changes along the length of the nozzle. In the subsonic part of the nozzle in the median plane, the perturbed pressure on the wall has a positive sign, and on the obstacle wall its sign-alternating. When an obstacle is in the subsonic part of the nozzle, the integral value of the lateral force is negative in comparison with positive for the supersonic part. [ABSTRACT FROM AUTHOR]

The production of powders with predetermined particle sizes is an important task in various branches of powder metallurgy and is especially relevant in additive manufacturing, where powders with an equivalent particle diameter smaller than 50 μm are used. The following parameters were calculated in the paper: theoretical gas flow speed to produce particles of required size by gas atomization of superheated fluid metal; specific flow rate of the metal flowing out of the metal tundish, and atomization nozzle parameters (such as critical and outlet cross-sectional areas and their ratio). Gas dynamics methods, being widespread in aviation engineering, were used to calculate the nozzle. The supersonic Laval nozzle parameters and gas dynamic parameters for atomization of the molten 10R6M5 tool steel were calculated at gauge gas pressures ranging from 0.5 to 2.0 MPa, allowing fine powders to be produced, including those with a particle size smaller than 50 μm. Graphical dependences were plotted to illustrate the theoretical speed at which particles of required size formed and the gas speed calculated as a function of the gas pressure before the atomization nozzle. A graphical method for determining the cross-sectional areas of the Laval nozzle and the inert gas flow speed for a given gauge pressure in the studied range was proposed. The following parameters for the production of 10R6M5 tool steel powders with a particle size smaller than 50 μm by gas atomization were established: gas flow speed at the nozzle outlet of 525 m/sec, temperature of –140°C, and pressure higher than 16.8 MPa. The calculated critical and outlet cross-sectional areas of the Laval nozzle were 110 and 290 mm2 and their ratio was 0.379. [ABSTRACT FROM AUTHOR]

• The Shockwave location and mass flow rate are the characteristics of the nozzle in a supersonic separator. • Nozzle simulation results are used to train Machine learning and neural network models. • Machine learning results are used for the prediction of mass flow rate and shockwave location. In the pursuit of cleaner energy sources, pre-processing fuel streams is crucial before distribution. Challenges arise during this process, leading to operational issues and diminished transmission efficiency. Among different technologies, supersonic separators are the ones that separate undesired components from the main gas stream more effectively. Precise forecasting of nozzle flow rate and shockwave location at a low cost can markedly enhance the efficiency of manufacturing and rating. In this research, the one-dimensional method has been developed to solve flow equations simultaneously by implementing equations of state. CFD has been used for the verification of the developed model, and the effect of different equations of state is investigated. Results show that the one-dimensional model significantly reduces the calculation time. Different EOSs result in up to 2.0 % and 3.5 % variation in the prediction of shock location and the mass flow rate, respectively. A machine learning methodology is employed to predict the location of shockwaves and the choked flow rate at an even lower cost. A dataset of 160 entries, generated using Peng Robinson's EOS, serves as the basis for this analysis. Prediction tasks are executed using Random Forest, k-nearest Neighbors, and Multilayer Perceptron models. While all three models demonstrate proficiency in data interpolation with R2 scores up to 0.9962 and 0.9951 for the shockwave location and mass flow rate, respectively, discerning their performance in extrapolation appears contingent on the specific case. In the case of extrapolation, Multilayer Perceptron and k-Nearest Neighbors show better match to one-dimensional results. [ABSTRACT FROM AUTHOR]

The cutting thickness of the flame cutting nozzle mainly depends on the characteristics of the cutting oxygen jet, and in the process of designing and manufacturing a flame cutting nozzle with an ultralarge thickness, it is impossible to carry out multiple experiments to optimize the design due to the difficulty in testing, safety, manufacturing cost, environmental pollution, and other problems. In this paper, the Laval-type cutting oxygen orifice channel was first designed by theoretical calculation, the pressure, velocity, Mach number, and density distribution characteristics of the cutting oxygen jet were investigated by numerical simulation, and the reliability and adaptability of the numerical simulation results were verified by experiments. Then, the numerical simulation comparison and estimation method of jet characteristics with the general-purpose G301-7# nozzle was used to study the cutting oxygen orifice channel of the ultralarge thickness flame cutting nozzle. The results show that under the condition of a 19 mm throat diameter and 10 atm inlet pressure, it was estimated that the length of cutting oxygen flow from the design nozzle can reach 1800 mm and the cutting thickness can reach 2500 mm based on the density value; the length of cutting oxygen flow can reach 2000 mm and the cutting thickness can reach 3800 mm based on the velocity value; the length of cutting oxygen flow can reach 1600 mm according to the value of the oxygen quality fraction; and the cutting thickness can reach 2800 mm based on the oxygen mass fraction content. Finally, trial production of the nozzle design, verification of the cutting test, the nozzle with a cutting thickness of 2500 mm at an oxygen pressure of 7 atm, and the cutting quality were all good. [ABSTRACT FROM AUTHOR]

The possibility of using a convergent-divergent nozzle with a Busemann diffuser in ramjet engines for aerospace engineering applications is studied. Kerosene vapors are considered as a fuel, the combustion of which is carried out in the detonation mode at a hypersonic speed of the oncoming air flow. It is shown that at the altitude of about 40 km with the flight Mach number of 9, the Busemann diffuser can provide stable detonation combustion of kerosene with the efficiency of over 50%. Modeling was carried out on the basis of two-dimensional unsteady Euler equations of motion for axisymmetric flows of a multicomponent reacting gas using the modification of the Godunov numerical scheme, which provides the second order of the solution approximation in terms of spatial variables. The previously published kinetic scheme of ignition and combustion of kerosene vapors is supplemented by the processes of low-temperature combustion of the initial fuel. • The possibility of initiation of kerosene vapor detonation in the Busemann diffuser is shown. • The Busemann diffuser for a scramjet based on detonation combustion of kerosene vapor is proposed. • In conditions of high-altitude atmosphere, the efficiency of such a scramjet may be higher than 50%. • The kinetic scheme is supplemented with low-temperature decomposition of kerosene. [ABSTRACT FROM AUTHOR]

The energy efficiency of a supersonic ramjet engine with detonation combustion of a hydrogen-air mixture in an axisymmetric Laval nozzle is considered. First of all, within the framework of the one-dimensional (1D) theory, it is shown that extreme combustion corresponding to the Chapman-Jouguet (C.-J.) deflagration, like constant pressure combustion, surpasses detonation in energy efficiency. However, this advantage becomes insignificant with an increasing the free-flow Mach number. Based on the results of the 1D theory, an axisymmetric Laval nozzle is constructed, which provides steady-state detonation combustion of a stoichiometric hydrogen-air mixture at an altitude of about 40 km and with freestream Mach numbers 9 and 12. The efficiency of detonation combustion in this case is about 35% instead of the maximum 65% according to the 1D theory. • In terms of efficiency, detonation reaches deflagration at a high flight Mach number. • In 1D-theory a stationary combustion in Laval nozzle has a maximum flight Mach number. • 1D theory gives overestimated values of the efficiency and expansion of the diffuser. • The detonation slope expands the limits of its applicability in terms of speed and height. • The steady-state detonation in the Laval nozzle can provide an efficiency of about 35%. [ABSTRACT FROM AUTHOR]

The existence of back pressure at outlet has a direct impact on the separation performance of the separation separator. However, the influence of back pressure is not understood well due to the complicated interaction of the supersonic flow, condensation and shock waves. In this study, the condensation flow models of water vapor were established, the influence of back pressure on supersonic condensation properties of water vapor was investigated. The results show that when the back pressure exists, the position of the shock wave is more forward than that without condensation, and the strength of shock wave is weaker. The nucleation rate is generated around the position of x = 115 mm and increases sharply from 0 to 1025 m−3 s−1. The shock wave is generated at x = 145 mm and x = 122 mm when the outlet back pressure is 20 kPa and 30 kPa, respectively. The condensed droplets evaporate again with the effect of shock wave, and then the secondary condensation of droplets occurs owing to the cooling effect of nozzle. When the back pressure is higher than a certain value, the refrigeration environment in the nozzle is completely destroyed with the effect of shock wave, and the condensed droplets evaporate again.

Abstract To simulate the transonic atomization jet process in Laval nozzles, to test the law of droplet atomization and distribution, to find a method of supersonic atomization for dust-removing nozzles, and to improve nozzle efficiency, the finite element method has been used in this study based on the COMSOL computational fluid dynamics module. The study results showed that the process cannot be realized alone under the two-dimensional axisymmetric, three-dimensional and three-dimensional symmetric models, but it can be calculated with the transformation dimension method, which uses the parameter equations generated from the two-dimensional axisymmetric flow field data of the three-dimensional model. The visualization of this complex process, which is difficult to measure and analyze experimentally, was realized in this study. The physical process, macro phenomena and particle distribution of supersonic atomization are analyzed in combination with this simulation. The rationality of the simulation was verified by experiments. A new method for the study of the atomization process and the exploration of its mechanism in a compressible transonic speed flow field based on the Laval nozzle has been provided, and a numerical platform for the study of supersonic atomization dust removal has been established.

For practical applications, the description of processes occurring during the flow of two-phase gas-liquid mixtures requires a simple physical and mathematical model that describes the behavior of a two-phase medium in the entire range of phase concentrations changes and in a wide range of pressure changes. Problems of this kind arise in various branches of industry and technology. In the space industry, one often has to deal with the movement of various gases in rocket nozzles, consider the combustion, condensation of various vapors on the nozzle walls and their further impact on the velocity sublayer at the nozzle wall. The large acoustic effect arising from the engines affects the gas-liquid mixture in the nozzles of rocket engines. In the metal industry, metal cooling occurs with the help of nozzles in which the emulsion mixture is supplied under high overpressure. But this is only a short list of applied issues in which one has to deal with a problem of this type. The paper presents the results and directions of study of the problems of two-phase dispersed gas-droplet flows in the nozzles. The main methods of investigation of two- phase heterogeneous flows are described. The main characteristics of heterogeneous two-phase flows in the nozzles, which were confirmed by experimental results, are presented. The calculation of the air-droplet flow in the Laval nozzle is given. The technique, which is based on integral energy equations for two-phase dispersed flows, is described. The main problems and questions concerning the further description and studying of two-component flows are stated.

The cold spray technology mainly accelerates the powder in the Laval nozzle by gas, ensuring that the powder has a greater velocity at the exit of the Laval nozzle, and achieving high-efficiency deposition on the substrate, thereby obtaining a better performance of the deposition coating. The article uses numerical simulation to study the influence of the length of the expansion section of the Dimet Laval nozzle on the acceleration effect of Al powder. The results show that the length of the expansion section of the nozzle is an essential factor affecting the velocity of the Al powder at the nozzle outlet. Through analysis, it can be known that the pressure inlet range of the Dimet Laval nozzle is 1.0 MPa, and the length of the expansion section is about 210 mm, which can ensure that the Al powder has a better acceleration effect in the nozzle and has a better velocity at the nozzle outlet. It is recommended that the joints between the small sections of the nozzle expansion section should be kept as smooth as possible so that the accelerating effect of the accelerating gas on the Al powder is more uniform and stable.

The possibility of stabilizing the detonation combustion of kerosene and gasoline vapors in a supersonic air flow entering an axisymmetric convergent–divergent nozzle with a central body under atmospheric conditions at an altitude of 16 km is studied numerically. The central body provides direct initiation of detonation due to the thermal and kinetic energy of the incident flow. The mathematical model is based on two-dimensional unsteady Euler equations for an axisymmetric flow of a multicomponent reacting gas and reduced kinetic models of combustion of flammable mixtures. The calculations use a modification of the numerical scheme of S.K. Godunov of the second order of accuracy in spatial variables. The central body of the cylinder–cone (CC) and cone–cylinder–cone (CCC) types is considered. The possibility of stabilizing the detonation combustion of kerosene at the oncoming flow of Mach numbers of M = 7 and 9 with thrust generation is shown. In the case of gasoline, only a small part of the mixture burns in the detonation mode behind the detached shock wave in front of the end wall of the central body. The thrust obtained in gasoline vapors does not compensate the aerodynamic resistance of the nozzle and the central body. [ABSTRACT FROM AUTHOR]

[Display omitted] • Development of an aerosol generator for generation of particles with different structures by desublimation. • CFD revealed a toroidal backflow in the expansion chamber behind the Laval nozzle. • Estimation of supersaturation of CuPc in an aerosol generator by a custom field function using CFD. • Core particles introduced into supersaturation zone by backflow lead to heterogeneous desublimation. • Heterogeneous desublimation of CuPc on TiO 2 cores and homogeneous desublimation of CuPc are obtained. In this work, a novel aerosol generator for submicron particles with a core-shell structure is presented. The operation process starts with the sublimation by heat of an organic material, copper phthalocyanine (CuPc), to form an under saturated gas flow. Then, the adiabatic expansion through a Laval nozzle is used to form a supersaturated free jet. Finally, by employing an active cooling and the injection of titanium dioxide (TiO 2) core particles, on the free jet side, the aerosol formation is enabled by the desublimation process. The Euler–Lagrange CFD simulations of the gas and particle flow revealed the rotating backflow of the core particles inside the cooled expansion chamber. Hence, the core particles are transported into the conical free jet region emerging from the Laval nozzle where the highest supersaturation of CuPc occurs. In addition to the numerical simulations, the resulting structure and size of the generated particles were experimentally investigated by employing scanning mobility particle sizer and a scanning electron microscope analysis. The surface of modified TiO 2 core particles showed a punctual coating with desublimated CuPc. [ABSTRACT FROM AUTHOR]

This study introduces a mathematical coupling model within the Euler-Lagrange framework to conduct numerical simulations for supersonic gas-particles flow. After validating the model, the gas flow characteristics and particle dynamics within supersonic gas-particle flow under various nozzle configurations are investigated. The findings are as follows: (1) A Laval nozzle with a smoothly connected throat suppresses the generation of fan-shaped Prandtl-Meyer expansion waves and other complex wave systems, effectively mitigating significant changes in gas pressure at the throat and enhancing the stability of supersonic jets. (2) The presence of a particle-free zone in the nozzle divergent segment reduces the collision frequency between particles and the walls, thereby restricting the radial expansion of particles. (3) Utilizing an internally smooth-lined nozzle and expanding the radial divergence angle to 2.5–2.8 times, while ensuring particles maintain consistent axial penetration performance, increases the reflective contact area. This leads to an improvement in the utilization efficiency of particles. These findings provide valuable insights for optimizing nozzle configurations and enhancing the performance of supersonic gas-particle systems. [Display omitted] • Impact of Laval nozzle geometry on supersonic gas-particles flow is revealed. • Laval nozzle with smoothly connected throat enhances the stability of supersonic jets. • Particle-free zone in nozzle divergent segment restricts radial expansion of particles. • Utilizing an internally smooth-lined nozzle expands the radial divergence angle. [ABSTRACT FROM AUTHOR]

• Non-equilibrium condensation models of ammonia-hydrogen mixture were established. • Accurate nucleation model for ammonia gas was selected based on experimental data. • Condensation characteristics of ammonia under different inlet conditions were studied. • Feasibility of supersonic separator for ammonia-hydrogen separation was confirmed. Ammonia has gained significant attention as a prospective hydrogen energy carrier. However, the effective separation of ammonia and hydrogen becomes a crucial aspect after the decomposition of ammonia into hydrogen. In this study, a novel method for ammonia separation is introduced, which leverages the phase transition behavior in supersonic flow. Consequently, this study presents the development of a mathematical model to elucidate the non-equilibrium condensation phenomenon of ammonia, and the accuracy of this model is validated. The simulation results reveal that, in comparison to classical nucleation theory (CNT) and internally consistent classical theory (ICCT), the Lothe-Pound (L-P) nucleation model more accurately characterizes the nucleation process of ammonia at low temperatures. Furthermore, numerical simulations demonstrated that increasing the inlet pressure from 1.2 bar to 1.8 bar led to a 2.66% enhancement in ammonia condensation efficiency. In contrast, raising the inlet temperature from 271 K to 283 K resulted in a decrease in condensation efficiency and a reduction in the radius of the exit droplets, potentially affecting subsequent separation efficiency. When the inlet ammonia molar fraction was elevated from 11% to 14%, the ammonia condensation efficiency increased from 13.7% to 14.5%, with only a minor decrease in outlet droplet radius (from 3.42 × 10−7 m to 3.39 × 10−7 m). These findings indicate that increasing pressure, decreasing temperature, and raising ammonia concentration can all stimulate ammonia condensation. These results have potential implications for the design and optimization of separators. [ABSTRACT FROM AUTHOR]

Two-phase nozzles, in which the phase transition process takes place, can work in jet superchargers for various purposes, including jet thermal pumps (steam-water injectors) and thermal compressors. In such schemes of thermal transformers, the ejector performs the function of a preliminary compression stage in order to reduce the load on the compression of the working substance in the main compressor. The use of fluxes of boiling liquid as energy-efficient working fluids is inhibited due to the lack of a reliable description of the mechanism of their flow. Finding the dependence of the steam content on the pressure and temperature at the nozzle exit will make it possible to determine the variant of the initial parameters at which the overproduction of steam will be greatest. It is also worth determining the change in the velocity factor, as well as the change in the thrust of the nozzle in the studied range of parameters, in order to find out whether the pressure at the nozzle outlet is a determining factor when choosing the design parameters of the nozzles. The article proposes to investigate the boiling streams in such nozzles by the method of mathematical modeling using a model that takes into account the relaxation nature of vaporization. The study used a compressible two-phase medium model, a kinetic model of evaporation / condensation. The model also takes into account the dynamic and mechanical equilibrium of the process of evaporation-condensation. The calculations were performed using an Ansys CFX commercial CFD product. The value of the mean square relative error of pressure measurement does not exceed 0,119%. The average discrepancy between the obtained data between the mathematical model and the field experiment does not exceed 3%.

Laval nozzle is the critical part of supersonic separator to provide refrigeration environment. Due to the back pressure at the outlet of supersonic separator in dehydration process, the condensation characteristics of water vapor and the refrigeration performances of the nozzles are affected by the shock wave. Herein, mathematical models for the supersonic condensation and flow of the methane-water two-phase flow model were established, which were verified by the experimental data. The effects of different divergent angles on the refrigeration and condensation behavior in the Laval nozzle were studied considering shock wave. The results show that the refrigeration performance of the nozzle will be worsen under the presence of shock waves. With the divergent angle of the nozzle increased from 2° to 8°, the lowest temperature was decreased from 304.4 K to 291.8 K, the liquid mass fraction at the nozzle outlet was decreased from 0.84% to 0.133%, the maximum droplet radius that can be obtained was reduced from 2.54 × 10−7 m to 1.69 × 10−7 m due to the forward movements of the shock waves. The divergent angle of the nozzle is recommended to be designed to 4°–6° in consideration of the refrigeration performance.

To pinpoint the relationship between high frequency tangential instability(HFTI) and continuous rotating detonation (CRD), series of H 2 /Air rotating detonations are experimentally achieved in the hollow chamber with Laval nozzle. The contraction ratio of the nozzle has a significant effect on the detonation. The detonation waves number increases with the increasing of equivalence ratio (ER) or nozzle contraction ratio. Based on its character, a new type of detonation is defined as two dominant peak one wave mode (TDPO). The velocities of detonation waves propagating in this new mode are larger than the Chapman-Jouguet (CJ) theoretic value. On the assumption that the reflection wave is rotated with the detonation wave, this mode is well illustrated. The forming process of two waves is also given. The results show that the appearance of combustion mode is relative to the reflection wave generated at the contraction section of the nozzle. The inner mechanism of the refection wave is illustrated. These works make a foundation to investigate the relationship between rotating detonation and tangential instability. • A new propagation mode named Two dominant peaks one-wave(TDPO)mode is presented. • The function of the reflection wave generated at the nozzle has been discussed. • This study verified the possibility of rotating detonation in hollow chamber with a nozzle. [ABSTRACT FROM AUTHOR]

Experimental investigation of the combined supersonic separator (CSS) characteristics was carried out and the results were compared with those from the vortex tube. The separator is a counter‐flow vortex tube with an energy separation chamber in the shape of a Laval nozzle; it can be used for hydrocarbon gas transportation preparation and power plant fuel gas drying. Numerical modeling was carried out to confirm the flow specifics in the examined separator structure. Although the cooling capability of the CSS is 30–50 % less than that of the vortex tube, its efficiency of moisture removal is twice as large, as is shown by the experimental research. The maximal cooling power corresponds to a cold flow fraction level of 0.39, while the range of optimal values for the moisture separation is 0.4–0.6. [ABSTRACT FROM AUTHOR]

Copyright of Larhyss Journal is the property of Biskra University, Research Laboratory in Subterranean & Surface Hydraulics 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.)

To simulate the transonic atomization jet process in Laval nozzles, to test the law of droplet atomization and distribution, to find a method of supersonic atomization for dust-removing nozzles, and to improve nozzle efficiency, the finite element method has been used in this study based on the COMSOL computational fluid dynamics module. The study results showed that the process cannot be realized alone under the two-dimensional axisymmetric, three-dimensional and three-dimensional symmetric models, but it can be calculated with the transformation dimension method, which uses the parameter equations generated from the two-dimensional axisymmetric flow field data of the three-dimensional model. The visualization of this complex process, which is difficult to measure and analyze experimentally, was realized in this study. The physical process, macro phenomena and particle distribution of supersonic atomization are analyzed in combination with this simulation. The rationality of the simulation was verified by experiments. A new method for the study of the atomization process and the exploration of its mechanism in a compressible transonic speed flow field based on the Laval nozzle has been provided, and a numerical platform for the study of supersonic atomization dust removal has been established. [ABSTRACT FROM AUTHOR]

The effect of nozzle pressure ratio n on the flow field of an air jet was investigated to obtain the basis of nozzle design. The flow field structure and abrasive acceleration of these nozzles were numerically simulated via Fluent, which was verified by I-Scan and erosion experiment. It was concluded that n is the primary factor that affects nozzle structure design, n = 1.12 can generate a better flow field structure. The dynamic pressure of the jet was measured via I-Scan, and the range of dynamic pressure variation was low when n = 1 and n = 1.12. Improvements in the flow field structure are more advance to the abrasive acceleration. The abrasive was accelerated to the maximum velocity at n = 1.12. Thus, n = 1.12 is the most advantageous to abrasive acceleration and material erosion wear. For example, the erosion depth and volume corresponding to n = 1.12 at 15 MPa increased by 60% and 27% when compared to n = 5. Unlabelled Image • The nozzle pressure ratio is the main factor of flow field structure of an abrasive air jet. • Full-expansion and low underexpansion exhibit a better flow field structure. • The pressure oscillation is disadvantageous to abrasive acceleration. • Nozzle with a nozzle pressure ratio of 1.12 is optimal to material removal rate. [ABSTRACT FROM AUTHOR]

Shock wave induces boundary layer separation when back pressure is set at the nozzle outlet. However, the effects of the complex flow characteristics on energy conversion mechanisms and the non-equilibrium phase transitions are not fully understood. This study developed a physical model for the homogeneous condensation of water vapour. The accuracy of the model was verified through flow and condensation experiments. The findings indicate that vortex clusters enhance energy transfer near the shear layer when the boundary layer separates. The separation point represents the region with the highest entropy generation. The peak entropy value near the wall with an increase of 7.07% as back pressure decreases from 0.75 to 0.1 MPa. The significant discovery that shock wave has minimal influence on droplet evaporation when the back pressure is 0.15 MPa, and the liquefaction efficiency at the outlet peaks at 79.42%. Moreover, over-expansion of the gas mixture at the back pressure of 0.15 MPa can lower the total pressure loss from 72.89% to 62.96% compared with the back pressure of 0.25 MPa. These findings provide an effective theoretical basis for determining optimal back pressures to reduce total pressure loss and enhance the liquefaction efficiency of the nozzle. [Display omitted] • Water condensation model predicts Wilson point with mean relative error of 3.10%. • Energy transfer under shock wave/boundary layer interaction of fluid is analyzed. • Separation point is highest entropy generation with entropy of 11.45 kJ kg−1 K−1. • Liquefaction efficiency peaks 79.42% with back pressure drops from 0.75 to 0.15 MPa. • Gas over-expansion at 0.15 MPa back pressure can lower total pressure loss to 62.96%. [ABSTRACT FROM AUTHOR]

In the duplex steelmaking process, the oxygen flow rate is suppressed to reduce the increasing rate of the temperature in the molten bath, resulting in severe dynamic conditions. To improve the mixing effect of the molten bath, a Laval nozzle structure designed for combination gas has been proposed. In this research, five types of Laval nozzle structure have been built based on the combination gas content, and both numerical simulations and experiments are performed to analyze the flow field of the supersonic jet. The axial velocity and oxygen concentration were measured in the experiment, which agreed well with the numerically simulated data. The results show that both initial axial velocity and potential core length increase with the flow rate of combination gas. Further, applying a higher N2 flow rate could improve the oxygen utilization rate at different ambient temperatures, but this issue increases the oxygen utilization rate; however, the latter can be reduced at higher ambient temperatures.

In this paper, we describe the possibility of using the energy of a compressed air flow, where cryogenic temperatures are achieved within the flow behind the nozzle, when reaching a critical flow in order to maximize the energy gained. Compared to the energy of compressed air, the energy obtained thermoelectrically is negligible, but not zero. We are therefore primarily aiming to maximize the use of available energy sources. Behind the aperture separating regions with a pressure difference of several atmospheres, a supersonic flow with a large temperature drop develops. Based on the Seebeck effect, a thermocouple is placed in these low temperatures to create a thermoelectric voltage. This paper contains a mathematical-physical analysis for proper nozzle design, controlled gas expansion and ideal placement of a thermocouple within the flow for best utilization of the low temperature before a shockwave formation. If the gas flow passes through a perpendicular shockwave, the velocity drops sharply and the gas pressure rises, thereby increasing the temperature. In contrast, with a conical shockwave, such dramatic changes do not occur and the cooling effect is not impaired. This article also contains analyses for proper forming of the head shape of the thermocouple to avoid the formation of a detached shockwave, which causes temperature stagnation resulting in lower thermocouple cooling efficiency.

When water vapor in moist air reaches supersaturation in a transonic flow system, non-equilibrium condensation forms a large number of droplets which may adversely affect the operation of some thermal-hydraulic equipment. For a better understanding of this non-equilibrium condensing phenomenon, a numerical model is applied to analyze moist air condensation in a transonic flow system by using the theory of nucleation and droplet growth. The Benson model is adopted to correct the liquid-plane surface tension equation for realistic results. The results show that the distributions of pressure, temperature and Mach number in moist air are significantly different from those in dry air. The dry air model exaggerates the Mach number by 19% and reduces both the pressure and the temperature by 34% at the nozzle exit as compared with the moist air model. At a Laval nozzle, for example, the nucleation rate, droplet number and condensation rate increase significantly with increasing relative humidity. The results also reveal the fact that the number of condensate droplets increases rapidly when moist air reaches 60% relative humidity. These findings provide a fundamental approach to account for the effect of condensate droplet formation on moist gas in a transonic flow system.

The article deals with the cavitation phenomenon affected by full and partial wetting of the wall. For the numerical computation of flow in the Laval nozzle the Schnerr-Sauer cavitation model was tested and was used for cavitation research of flow within the nozzle considering partial surface wetting. The coefficient of wetting for various materials was determined using experimental, theoretical and numerical methods of fluid flow due to partial surface wetting.

• A new method for hydrogen sulfide removal using Laval nozzle was proposed. • Mathematical model for the supersonic condensation of binary mixture was established. • Condensation characteristics of methane-hydrogen sulfide mixture were analyzed. • Influence of different inlet parameters on condensation process was investigated. A new method was proposed for hydrogen sulfide removal from natural gas through the utilization of supersonic flow in a Laval nozzle. For this purpose, a mathematical model was established for the supersonic non-equilibrium condensation flow of the binary methane-hydrogen sulfide mixture. The condensation parameters were numerically calculated and described in detail, and a sensitivity analysis was carried out to investigate the influence of the inlet parameters on the supersonic condensation flow. The results show that when the inlet temperature and pressure were 290 K and 5 MPa respectively, and the mole fraction of hydrogen sulfide was 15%, the removal efficiency of hydrogen sulfide was 64.83%, which indicates that the use of supersonic separation technology for this application is indeed feasible. It was also found that with the decrease of inlet temperature or the increase of inlet pressure, the nucleation site moved forward (i.e. closer to the throat), and the maximum droplet radius and liquid mass fraction of hydrogen sulfide increased. When the mole fraction of hydrogen sulfide was less than 5%, however, the liquid mass fraction of hydrogen sulfide was almost zero. Therefore, it appears that using a reasonable hydrogen sulfide fraction, a lower inlet temperature, and a higher inlet pressure can promote the supersonic condensation of hydrogen sulfide in the Laval nozzle and improve the efficiency of the removal process. These results suggest that supersonic separation technology can provide an efficient and environment-friendly way to remove hydrogen sulfide from natural gas, thereby reducing emissions. [ABSTRACT FROM AUTHOR]

Rotating detonation engines (RDEs) are widely studied because of their compact configurations and high thermal cycle efficiency. In this paper, a series of numerical investigations of a non-premixed hollow RDE are performed. The transient explicit density-based solver in ANSYS Fluent is used to perform the simulations. For a hollow RDE without Laval nozzle, there is only one rotating detonation wave in the combustion chamber. Compared to the traditional annular RDE, the mixing quality is deteriorated, and the thrust of the engine decreases and becomes more unstable. When the hollow RDE is attached with a Laval nozzle, there are two rotating detonation waves in the combustion chamber. The pressure within the combustion chamber increases while the axial velocity decreases. The mixing quality is improved. The height of detonation waves decreases with larger contraction ratio of the nozzle. A Laval nozzle is beneficial for a hollow RDE to achieve steadier operation and higher thrust output. When the contraction ratio is 4, the propulsive performance of the engine is the highest. The maximum thrust achieved is 840 N. • The flowfield structure in a non-premixed hollow RDE is obtained. • The mixing quality is deteriorated in the hollow RDE. • The height of detonation waves decreases with larger CR of the nozzle. • A Laval nozzle is beneficial to achieve steadier and higher thrust output. [ABSTRACT FROM AUTHOR]

Abstract The condensation of water steam in Rankine cycle's turbines occurs usually at the subcritical region far away from the critical point, while that of the supercritical carbon dioxide in Brayton cycle' compressors occurs generally at the supercritical region and near the critical point. However, it's not known about that flow characteristics of those common, condensable working fluids in the range of subcritical and supercritical regions. In this paper, the equilibrium condensation and expansion characteristics of water steam and CO 2 in a Laval nozzle under the same dimensionless nozzle inlet conditions were investigated numerically. Firstly, the results show that the wetness fraction distribution of each working fluid is different under different nozzle inlet conditions, while the variation trend of wetness fraction are totally similar for both working fluids. This phenomenon implies that the main factor that influences the variation trend of wetness fraction is the nozzle inlet conditions rather than the type of working fluids. Secondly, the nozzle outlet Mach number of CO 2 is lower than that of water steam. And with the increasing of inlet total pressure, the total pressure loss decreases, and that of CO 2 is lower than that of water steam under the same nozzle inlet conditions. Highlights • Condensation characteristics of H 2 O and CO 2 in all ranges are compared. • Affecting factor of condensation is nozzle inlet conditions rather than fluids. • Condensation at supercritical region should be paid much more attention. • Total pressure loss decreases with the increasing of nozzle inlet total pressure. • Total pressure loss of CO 2 is lower than that of H 2 O under same inlet conditions. [ABSTRACT FROM AUTHOR]

A novel generator for a defined test aerosol consisting of nonspherical particles was developed based on the desublimation of copper phthalocyanine during adiabatic cooling. Employing a brush disperser, copper phthalocyanine powder is dosed and dispersed in a nitrogen flow and sublimated in a tube furnace. Downstream the furnace new particles are formed due to the adiabatic expansion and the desublimation of the material in a laval nozzle. The generated particles were characterized employing a scanning mobility particle sizer and an aerosol particle mass analyzer to determine the size distribution and the dynamic shape factor. For the operating parameters of the generator examined here, particles with a mobility diameter between 30 and 600 nm were generated. The measured values for the dynamic shape factor of the particles were confirmed by scanning electron microscopy analysis. The aerosol generator uses the desublimation of copper phthalocyanine to generate airborne nonspherical particle structures. An analysis of the generated particles by scanning electron microscopy and by measuring the dynamic shape factor provides information about the particle structure. The generated particles show a fibrous shape which can be affected by the operating parameters of the generator. [ABSTRACT FROM AUTHOR]

Two-phase nozzles, in which the phase transition process takes place, can work in jet superchargers for various purposes, including jet thermal pumps (steam-water injectors) and thermal compressors. In such schemes of thermal transformers, the ejector performs the function of a preliminary compression stage in order to reduce the load on the compression of the working substance in the main compressor. The use of fluxes of boiling liquid as energy-efficient working fluids is inhibited due to the lack of a reliable description of the mechanism of their flow. Finding the dependence of the steam content on the pressure and temperature at the nozzle exit will make it possible to determine the variant of the initial parameters at which the overproduction of steam will be greatest. It is also worth determining the change in the velocity factor, as well as the change in the thrust of the nozzle in the studied range of parameters, in order to find out whether the pressure at the nozzle outlet is a determining factor when choosing the design parameters of the nozzles. The article proposes to investigate the boiling streams in such nozzles by the method of mathematical modeling using a model that takes into account the relaxation nature of vaporization. The study used a compressible two-phase medium model, a kinetic model of evaporation / condensation. The model also takes into account the dynamic and mechanical equilibrium of the process of evaporation-condensation. The calculations were performed using an Ansys CFX commercial CFD product. The value of the mean square relative error of pressure measurement does not exceed 0,119%. The average discrepancy between the obtained data between the mathematical model and the field experiment does not exceed 3%. [ABSTRACT FROM AUTHOR]

Abstract In order to study the effects of external particles on the supersonic condensation process of natural gas, an experimental system to test the supersonic condensation efficiency is set up and the models for spontaneous (homogeneous) and heterogeneous condensation of natural gas are established. Vapor and liquid flow control equations are derived based on the two-fluid Euler model, and internally consistent classical theory and Gyarmathy's model are used to calculate the droplet nucleation rate and growth rate respectively. The results show that the due to the inhomogeneous condensation caused by the external particles, the measured droplet radius is larger, but the number of droplets is smaller in the experiment. With the increase of external particle concentration, the spontaneous condensation is gradually suppressed and heterogeneous nucleation is becoming more and more obvious. The increase of external particles concentration is beneficial to the condensation and the total humidity becomes larger, but when the external particle concentration increases to a certain value, the promotion effect is limited. In addition, other parameters such as the radius of particles also have influence on the heterogeneous condensing flow of natural gas. Graphical abstract Unlabelled Image Highlights • Physical and mathematical models for heterogeneous condensation are established. • Experimental system to test the supersonic condensation efficiency is set up. • Condensation parameters of spontaneous and heterogeneous nucleation are compared. • Effects of external particles on heterogeneous condensation process are analyzed. [ABSTRACT FROM AUTHOR]

Graphical abstract The numerical simulations of CH 4 -CO 2 mixture gas in the nozzle were carried out applying User Define Function, which convergent section is designed by different curves respectively. Due to the intense performance of spontaneous condensation and the stable variation of temperature and pressure, Translation of Witoszynski curve is recommended to design the convergent section in supersonic separator. Highlights • Two-dimensional models of Laval nozzle were set up with different convergent section. • The numerical simulations of CH 4 -CO 2 mixture gas in the nozzle were carried out. • Condensation and flow parameters were obtained using User Define Function. • Translation of Witoszynski curve is recommended to design the convergent section. Abstract The Laval nozzle is an important part of the supersonic separator, which structure determines the separation efficiency of supersonic separator. In order to study the flow and condensation process in Laval nozzle with different convergent section, convergent section is designed by Bicubic parametric curve, Quintic polynomial curve, Witoszynski curve and Translation of Witoszynski curve, respectively. The numerical model for the supersonic condensing flow process of CH 4 -CO 2 mixture gas is established and the User Define Function is invoked for numerical simulation. The effects of different linetypes of convergent section on the flow and condensation parameters in nozzle were investigated. The results confirm the Laval nozzle designed by Translation of Witoszynski curve has strengths such as the most stable pressure change, the best refrigeration effect, the most intense spontaneous condensation, and the nucleation rate is 1.610×1022m−3s−1, the number of droplets is as high as 2.023×1015m−3 at the nozzle outlet far better than the other nozzles. Therefore, Translation of Witoszynski curve is recommended to design the convergent section of Laval nozzle in supersonic separator. [ABSTRACT FROM AUTHOR]

• A method for simultaneous removal of CO 2 and H 2 S from natural gas was discussed. • Condensation characteristics of CO 2 and H 2 S with different components were studied. • Condensation nuclei of CO 2 promoted heterogeneous nucleation of H 2 S in ternary gas. • Co-condensation mechanisms and liquefaction efficiency of CO 2 /H 2 S were clarified. Supersonic separator offers a new research field for the simultaneous purification of acidic gases (such as carbon dioxide (CO 2) and hydrogen sulfide (H 2 S)). However, the condensation characteristics and interaction mechanism of various acidic components in the methane (CH 4) are not clear, resulting in low liquefaction efficiency. In this paper, mathematical models of homogeneous nucleation of the CH 4 -CO 2 /CH 4 -H 2 S binary mixture and heterogeneous condensation of the CH 4 -CO 2 -H 2 S ternary mixture were established. Numerical calculations and a detailed description of the condensation process were carried out. The results demonstrate that the liquefaction efficiency of CO 2 can reach a high of 67.47 % by the homogeneous nucleation in the CH 4 -CO 2 , whereas the liquefaction efficiency of H 2 S is only 16.91 % in the CH 4 -H 2 S when the condensable inflow mole fraction is 10 %. The heterogeneous condensation of H 2 S will be promoted by the condensation nuclei of CO 2 in the CH 4 -CO 2 -H 2 S. Although the nucleation rate of H 2 S is significantly reduced from 4.88 × 1021 to 0.369 m−3·s−1 compared with the CH 4 -H 2 S, the liquefaction efficiency of H 2 S is greatly increased from 16.91 % to 39.5 %. In actual gas processing, the condensation nuclei of CO 2 will promote the heterogeneous condensation of the component H 2 S and increase the condensation efficiency of the H 2 S droplets. [ABSTRACT FROM AUTHOR]

Supersonic oxygen-powder jet injection has spanned wide range of operations in chemical engineering. However, the ubiquitous polydispersity of solid powder known to exert different flow behavior than the monodisperse counterpart has not been revealed. In this work, numerical simulation of the supersonic oxygen-powder jet injection via the Laval nozzle is performed under the Eulerian-Lagrangian framework to explore the impact of wide continuous size distribution of solid phase on the gas-solid hydrodynamics. Specifically, the gas phase is solved using the Eulerian method, while the particle motion is tracked under the Lagrangian framework. The numerical model is well validated with the experimental measurements. The results reveal that the blending of particles restricts the gas phase expansion, leading to the obvious reduction of gas velocity and increase of gas temperature. Additionally, a narrow particle size distribution (PSD) width corresponds to a higher proportion of large particles, inducing stronger vortices and hindering gas phase expansion. With regard to solid phase, the penetration ability of particles is significantly enhanced within the supersonic gas flow by accelerating the particle velocity to about 300 m/s. Furthermore, particles with wider PSD exhibit increased sensitivity to interphase interaction, particle-particle collisions and lift forces, resulting in higher velocities, lower temperatures along the axial direction and greater dispersion along the radial direction. Lastly, the interphase heat transfer mainly occurs in the convergent section, divergent section, and one nozzle length downstream from the nozzle exit. The findings obtained in this study offer valuable insights for industrial applications. [Display omitted] • Supersonic gas-solid mixing flow in Laval nozzle is numerically simulated. • The effect of PSD width on gas phase and particle dynamic are explored. • The interphase interaction mainly occurs inside and downstream of nozzle exit. • Particles with larger PSD width is more sensitive to interphase interaction. • Narrower PSD width has stronger ability of inducing vorticity. [ABSTRACT FROM AUTHOR]