Multiphase Flow Field Research Articles

Numerical research on flow field structure and droplets distribution of kerosene-fueled rotating detonation ramjet engine

In order to reveal the multiphase flow field structure and fuel droplets distribution under rotating detonation ramjet engine fueled by liquid kerosene, non-premixed simulations coupled with an Euler-Lagrangian approach is adopted. Supersonic air is used as oxidizer and the total pressure and total temperature at the entrance of isolation are set as 1.2 MPa and 1100 K, respectively, with a Mach number of 1.9. It is shown that a single-wave is formed and typical rotating detonation wave structures are established under two different orifice spacing conditions, namely 2 mm and 6mm. A "rich oil and poor oxygen band" is formed and attributed to the inconsistent supply of fuel and air after the passage of the detonation wave. When the orifices spacing is increased from 2 mm to 6 mm, both obvious strips after the detonation wave and “n-type” deflagration structures near the contact surface are observed. Besides, the detonation wave front becomes discontinuous, as well as from the deflagration heat release distribution. Despite of the effect of the circumferential propagation of detonation wave, kerosene droplets still propagate mainly along the downstream direction. However, Kerosene droplets distribution shows obvious difference along the detonation wave propagation direction.

Effects of axial launch spacing on cavitation interference and load characteristics during underwater salvo

This paper analyzes the effect of launch interval on cavitation flow interference and load characteristics during underwater salvo. The study employs the Improved Delayed Detached Eddy Simulation and the Schnerr-Sauer cavitation model, Volume of Fluid (VOF) multiphase flow model, and overlapping grid. Additionally, decompression experiment systems are designed, and numerical simulations are found to be in good agreement with experimental results, thus verifying the effectiveness of the simulation. Detailed discussions are provided on multiphase flow field and load distribution. The results reveal a top-down collapse process of the cavity, with collapse shrinking to an isolated bubble at the end. Synchronized collapse pressure is characterized by short pulse widths at the peaks, all located at the lowermost part of the cavity. During the underwater stage, when the axial launch spacing ranges between 0.5 times and 1.0 times the length of the projectile, the head of the second projectile acts on the area below the center of mass of the first. This leads to gradual stabilization of the initial cavity and a decrease in deviation of the center of mass toward the inside. Despite experiencing large-scale fracture and detachment due to interference from the wake of the first engine, the motion stability of the inside cavity of the second projectile remains intact. In the water exit stage, when the axial launch spacing ranges between 0.75 times and 1 time the length of the projectile, it causes expansion and contraction of the inside cavity of the second projectile. However, asymmetric synchronous collapse loads may occur, leading to unstable motion posture.

Deep Learning Based Method for Dynamic Tracking of Bubbles in Microfluidic Gas-Driven Water Experiments

Using microfluidic chips for gas displacement experiments is an important approach for studying CO2 displacement mechanisms and gas-liquid exchange processes. Analyzing the micro-scale distribution of gas and water during gas displacement enables the optimization of injection strategies, offering valuable guidance for enhancing oil and gas recovery rates. Traditional image processing techniques often face challenges in effectively handle the complex gas-liquid flow dynamics and irregular bubble shapes encountered in gas displacement experiments. To address this challenge, this paper proposes a gas bubble detection and tracking method for gas-driven water microfluidic experiments based on domain adaptation in deep learning and improved YOLOv8. Using the CycleGAN style transfer network to generate numerous simulated bubble training samples significantly reduces the manual labeling workload for bubbles. Additionally, the SE attention mechanism is integrated into the YOLOv8 backbone network to enhance the feature extraction capability of bubbles, and the Fast-PConv Head structure is incorporated into the detection head to enhance detection efficiency. Experimental results demonstrate that using just 20 annotated experimental images, the bubble detection accuracy of the proposed method can reach 94%. Lastly, DeepSORT is employed to track bubbles and visualize the dynamic trends of bubble changes in the form of visual charts. The deep learning approach proposed in this paper provides a new perspective for intelligent analysis of bubbles in microfluidic chip experiments, and future work aiming to its application to the complex multiphase flow field in porous media.

A comprehensive review of advances in physics-informed neural networks and their applications in complex fluid dynamics

Physics-informed neural networks (PINNs) represent an emerging computational paradigm that incorporates observed data patterns and the fundamental physical laws of a given problem domain. This approach provides significant advantages in addressing diverse difficulties in the field of complex fluid dynamics. We thoroughly investigated the design of the model architecture, the optimization of the convergence rate, and the development of computational modules for PINNs. However, efficiently and accurately utilizing PINNs to resolve complex fluid dynamics problems remain an enormous barrier. For instance, rapidly deriving surrogate models for turbulence from known data and accurately characterizing flow details in multiphase flow fields present substantial difficulties. Additionally, the prediction of parameters in multi-physics coupled models, achieving balance across all scales in multiscale modeling, and developing standardized test sets encompassing complex fluid dynamic problems are urgent technical breakthroughs needed. This paper discusses the latest advancements in PINNs and their potential applications in complex fluid dynamics, including turbulence, multiphase flows, multi-field coupled flows, and multiscale flows. Furthermore, we analyze the challenges that PINNs face in addressing these fluid dynamics problems and outline future trends in their growth. Our objective is to enhance the integration of deep learning and complex fluid dynamics, facilitating the resolution of more realistic and complex flow problems.

Reconstructing Multiphase Flow Fields with Limited Pressure Observations Based on an Improved Transformer Model

In practical applications, the implementation of active cavitation control can significantly enhance the hydrodynamic performance of underwater vehicles. However, the sparsity of sensor information poses a substantial challenge to acquiring flow field states. Recent advances in deep learning offer reliable solutions to this problem. Specifically, deep learning methods, through the construction of sparse reconstruction models, establish connections between sparse observational information and flow field states with minimal or no prior knowledge. To reconstruct multiphase flow fields from sparse pressure observations on the hydrofoil surface, this work proposes a Transformer-based sparse reconstruction model. Test results on cavitation datasets demonstrate that the model's predictions of cavity contours, cavity lengths, and cavity volumes are highly consistent with actual results during the sheet cavity growth and cavity shedding stages. However, due to the highly unsteady nature of cavitation flow and the lack of far-field information, the model's prediction performance is limited during the cloud cavity aggregation and collapse stages. This model exhibits potential in the sparse reconstruction of multiphase flow fields, providing support for the observation of flow field states and active cavitation control.

Numerical Study on Characteristics of Lead-Bismuth Lubricated Hydrodynamic Bearing Considering Non-Condensable Gas

Lead-Bismuth Eutectic (LBE) is an interesting candidate as a coolant for Generation IV nuclear power plants. Lead-bismuth lubricated radial guide bearing is the key component of the mechanical pump in a lead-bismuth coolant system. In this paper, the transient calculation model of multiphase lubrication flow field of journal bearing is established by using Singhal full cavitation model and structured dynamic grid technique. Due to the saturated vapors of LBE being very low, the effects of different Non-Condensable Gas (NCG) contents on the characteristics of lead-bismuth lubricated journal bearing systems were analyzed. The results show that the NCG content has an obvious influence on the working state of the bearing. With the increase in NCG content, the bearing load capacity decreases. Under the same load, with the increase in NCG content, the eccentricity of the static equilibrium position will be larger, which will increase the risk of bearing contact with the bearing bush. Moreover, the increase of NCG content will lead to the increase of tangential oil film force work, which is helpful to improve rotor stability.

Computational Fluid Dynamics Study on Bottom-Hole Multiphase Flow Fields Formed by Polycrystalline Diamond Compact Drill Bits in Foam Drilling

High-temperature geothermal wells frequently employ foam drilling fluids and Polycrystalline Diamond Compact (PDC) drill bits. Understanding the bottom-hole flow field of PDC drill bits in foam drilling is essential for accurately analyzing their hydraulic structure design. Based on computational fluid dynamics (CFD) and multiphase flow theory, this paper establishes a numerical simulation technique for gas-liquid-solid multiphase flow in foam drilling with PDC drill bits, combined with a qualitative and quantitative hydraulic structure evaluation method. This method is applied to simulate the bottom-hole flow field of a six-blade PDC drill bit. The results show that the flow velocity of the air phase in foam drilling fluid is generally higher than that of the water phase. Some blades’ cutting teeth exhibit poor cleaning and cooling effects, with individual cutting teeth showing signs of erosion damage and cuttings cross-flow between channels. To address these issues, optimizing the nozzle spray angle and channel design is necessary to improve hydraulic energy distribution, enhance drilling efficiency, and extend drill bit life. This study provides new ideas and methods for developing geothermal drilling technology in the numerical simulation of a gas-liquid-solid three-phase flow field. Additionally, the combined qualitative and quantitative evaluation method offers new insights and approaches for research and practice in drilling engineering.

Research on icing model and calculation methods

Aircraft icing seriously threatens flight safety. This paper describes a modified shallow-water icing thermodynamic model that is applicable to unstructured grids and considers the effects of changes in water physical parameters and sublimation on icing. An icing calculation method enables the automatic determination of whether freezing occurs and the type of icing. An autonomous icing calculation program is developed to extract the geometric coordinates and mesh information of the icing surface and combine this information with the multiphase flow field of air-supercooled water droplets. The icing equations in the Godnov format are discretized to produce a large-scale sparse matrix that is solved iteratively using the biconjugate gradient stabilized method. The output includes parameter distributions for the ice thickness, water film thickness, and equilibrium temperature. Taking the National Advisory Committee for Aeronautic 0012 airfoil as the study object, the results of icing simulations are compared with experimental data from an ice wind tunnel and the ice shapes calculated by the FENSAP-ICE software. The results are found to be in good agreement with the experimental data, and the ice height errors at stagnation points are less than 15%. In the case of rime ice, single-horned ice shapes are simulated for both conventional and large supercooled droplets. For mixed ice and glaze ice, double-horned ice shapes are simulated for both droplet conditions. FENSAP-ICE fails to simulate the ice horns and produces large errors in ice thickness and ice range.

Numerical investigation of the multiphase flow and loading state of underwater semiclosed initial interrupted bubbles

The pulsation of bubbles and the impact load from reverse flow, generated by the evolution of semiclosed initial intermittent bubble multiphase flow during underwater launches, are crucial factors affecting launch safety. This paper employs the mixture multiphase flow model and the interphase heat and mass transfer model to simulate the interaction between the gas inside a partially enclosed cylinder and the water medium outside the cylinder, combined with simulation and piggybacking experiments, to analyze the flow process and load state. The numerical model is further utilized to study the evolution of the multiphase flow field of the semienclosed initial intermittent bubble, the pulsating load of the bubble, the impact load of the inverted water flow, and the influence of structural dimensions on the load. The results show that the initial intermittent bubble in the mouth of the cylinder experiences an expansion–contraction–expansion pulsation process, and as the migration of the interface between the phases results in significant pressure pulsation, the peak pulsation can exceed twice the pressure difference between the initial gas pressure inside the cylinder and the hydrostatic pressure at the mouth of the cylinder. At the late stage of bubble pulsation, a large amount of water with pulsating bubbles flows into the semiclosed cylinder, and the pulsation-induced velocity and gravity are used to form a high-speed inverted water flow. The interaction between the inverted water and the gas inside the cylinder generates an oscillating shock load where the maximum shock load is significantly greater than the ambient pressure load. Additionally, the effect of structural dimensions on the load state under the same intermittent conditions is examined.

Nozzle Wear in Abrasive Water Jet Based on Numerical Simulation.

Particle diameters and jet pressure in abrasive water jet (AWJ) are significant jet properties which deserve a better understanding for improving AWJ machining performance. Some influence factors have been verified regarding nozzle wear in abrasive water jet polishing application. A three-dimensional model of a nozzle is established to analyze the influence of internal multi-phase flow field distribution, which is based on Euler-Lagrange methodology. With the increase of jet pressure, the erosion rate decreases; with the increase of the diameter and mass flow rate of the erosion particles, the erosion speed increases as well. When the diameter of the outlet is worn to 1.6 mm, the pressure on the work piece caused by the abrasive water jet increases by more than double compared to the non-worn nozzle; when the diameter of the nozzle outlet is worn to 1.6 mm, the shear force is 2.5 times higher than the shear force when the diameter is 1.0, which means that the jet force is divergent when the diameter is 1.6 mm, and the damage of the work piece is very serious. The obtained results could improve polishing efficiency on the work piece, extend nozzle lifetimes, and guide the future design of AWJ nozzles.

CFD–DEM method is used to study the multi-phase coupling slag discharge flow field of gas-lift reverse circulation in drilling shaft sinking

To elucidate the distribution law of the multiphase coupling slag discharge flow field in gas-lift reverse circulation during drilling shaft sinking, a numerical analysis model of gas–liquid–solid multiphase coupling slag discharge was established by CFD–DEM (Coupling of computational fluid dynamics and discrete element method) method, taking the drilling of North Wind well in Taohutu Coal Mine as an example. This model presented the distribution of the multiphase flow field in the slag discharge pipe and at the bottom hole, and was validated through experimentation and theoretical analysis. Finally, the impact of factors, including bit rotation speed, gas injection rate, air duct submergence ratio, and mud viscosity on the slag discharge flow field was clarified. The results indicated that the migration of rock slag at the bottom of the well was characterized by “slip, convergence, suspension, adsorption, and lifting”. The slag flow in the discharge pipe exhibited the states of “high density, low flow rate” and “low density, high flow rate”, respectively. The multiphase fluid flow patterns in the well bottom and slag discharge pipe were horizontal and axial flows, respectively. The model test of the gas lift reversed circulation slag discharge and the theoretical model of the bottom hole fluid velocity distribution confirmed the accuracy of the multiphase coupling slag discharge flow field distribution model. The rotation speed of the drill bit had the most significant impact on the bottom hole flow field. Increasing the rotation speed of the drill bit can significantly enhance the tangential velocity of the bottom hole fluid, increase the pressure difference between the bottom hole and annular mud column, and improve the adsorption capacity of the slag suction port. These findings can provide valuable insights for gas lift reverse circulation well washing in western drilling shaft sinking.

Research on the cooling mechanism of low-temperature liquid jet mixing in high-temperature and high-speed airflow

The multi-stage water spray cooling system of the space launch site involves a complex gas–liquid two-phase mixed cooling problem in the process of spraying water onto the rocket engine gas jet. To investigate the complex multiphase flow field of the interaction between the airflow and liquid water jet, the Mixture multiphase flow model is adopted, which is coupled with the vaporization equation and component transport model of liquid water. The computational fluid dynamics method is used to numerically analyze the mixing and cooling mechanism of low-temperature liquid jet in high-temperature and high-speed gas flow. The results show that mixing low-temperature liquid jets in high-temperature and high-speed airflow can cause the exchange of momentum and energy, resulting in pressure loss and temperature reduction in the gas phase flow field. Due to the acceleration of transverse airflow, the diffusion flow range of the jet is significantly increased, and violent vaporization occurs, which further consume a large amount of airflow energy. The mixing cooling effect of transverse airflow and liquid water jet is directly related to the mass flow rate ratio of the jet to airflow. In addition, directly designing liquid water jet orifices on the solid wall of the guiding device can achieve the effect of improving the gas flow field environment. This conclusion can provide theoretical reference for the thermal protection design of ground launch devices in space launch site.

Research of the Influence of Lateral Inflow Angles on the Cavitation Flow and Movement Characteristics of Underwater Moving Objects

This study examined the multi-phase flow field for a single object and two parallel/series objects under different incoming angles of lateral flow. The volume of fluid model, the Sauer–Schnerr cavitation model, and the six degrees of freedom (DOF) method were adopted to consider simulations of multi-phase flow, phase change, and object movement, respectively. The results show that, for a single object, the degree of asymmetry in the cavity profile depends on the component (the z-component) of the lateral inflow velocity in the direction perpendicular to the initial velocity of the object. As this component increases, the asymmetry of the cavity increases. The cavity length is related to the relative axial speed between the object and the water. For parallel objects, the cavity asymmetry is determined by the superimposed influence of the z-component of the lateral incoming speed and the high-pressure zone induced by the nearby object. The object located downstream relative to the lateral flow has a stronger cavity asymmetry than that of the upstream object, and the trajectory of the downstream object is more easily deviated than that of the upstream object. For tandem objects, with the increase in the lateral incoming angle, the supercavity length increases after the rear object enters into the front cavity. With the increase in the z-component of the lateral flow velocity, the deviation speed increases.

Influence of side dilution jets on swirling and non-swirling pulverised biomass turbulent annular flows

The use of pulverised biomass in non-premixed combustion systems, featuring turbulent annular flows (swirling, non-swirling) with downstream air dilution jets, is of immense practical importance. The overall combustion performance and emissions heavily rely on the underlying flow dynamics, turbulence and dispersion behaviour of the pulverised biomass particles. Despite the practical significance of side dilution jets in aiding complete combustion and controlling pollutants, the fundamental understanding of side dilution jets influence on the biomass particle velocity field, turbulence, and dispersion characteristics is still lacking. However, the presence of a multi-phase (solid-gas) flow field, highly turbulent annular flows, swirl, and cross-wise turbulent dilution jets poses significant challenges to these investigations. This work employs a combination of two-dimensional planar Particle Image Velocimetry (PIV) experiments and three-dimensional multi-phase numerical modelling to resolve the influence of turbulent side dilution jets (Red = 18,000 and 27,000) on the particle flow and dispersion characteristics of turbulent annular jets equipped with a central pulverised biomass-laden jet. The numerical modelling uses Reynolds stress model (RSM) and discrete phase model (DPM) for the solution of gas and dispersed phases, respectively. Walnut flour based raw pulverised biomass is injected at a certain particle loading ratio (Φp=0.33 and 0.49) through a turbulent central jet (Rj = 4500) into non-swirling (S = 0) and swirling (S = 0.3) turbulent confined annular flows (Res = 35,500 and 17,800). Comprehensive Constant Temperature Anemometry (CTA) experiments are conducted to obtain well-defined boundary conditions for experiments as well as numerical simulations. Prior to numerical predictions, the models are duly validated against the experimental data.Results reveal that the characteristic flow feature of side dilution jets, i.e., peripheral recirculation zones (PRZ) significantly entrains pulverised biomass particles from the turbulent particle-laden (central jet) annular flows (both swirling and non-swirling) and alters the particle flow and turbulence characteristics. Under non-swirling conditions (S = 0), side dilution jets reduce mean particle axial velocity by 22.4% and increase turbulent fluctuating velocity by 52.6%. These figures elevate to 32.5% and 100% respectively for swirling conditions (S = 0.3), depicting enhanced turbulent mixing between solid particles and the gas phase. In terms of particle dispersion, side dilution jets significantly enhance lateral dispersion of biomass particles, particularly under swirling flow conditions. In the PRZ region, side dilution jets led to a 108% and 279% increase in normalised particle count for non-swirling and swirling cases, respectively. These findings suggest that swirl doubles the particle dispersion in the PRZ. Furthermore, a 50% increase in Red enables side dilution jets to entrain more biomass particles and disperse them into the PRZ. Conversely, a 50% increase in ṁp leads to a significant increase in particle volume fraction along the central axis of the nozzle.

Morphological analysis for thermodynamics of cavitation collapse near fractal solid wall

A fractal geometric boundary with natural wall features is introduced into a hybrid lattice-Boltzmann-method (LBM) multiphase model. The physical model of cavitation bubble collapse near the irregular geometric wall is established to study the thermodynamic characteristics of the bubble collapse. Due to the lack of periodicity, symmetry, spatial uniformity and obvious correlation in the LBM simulation of the bubble collapse near the fractal wall, the morphological analysis based on Minkowski functional is introduced into the thermodynamic investigation of cavitation bubble so as to analyze and obtain the effective information. The results show that the Minkowski functional method can employed to study the temperature information in complex physical fields hierarchically and quantitatively. The high/low temperature region of the cavitation flow is explored, and thermal effect between irregular and fractal geometric wall and cavitation bubble can be revealed. It illustrates that LBM and morphological analysis complement each other, and morphological analysis can also be used as an optional and potential tool in research field of complex multiphase flows.

4D microvelocimetry reveals multiphase flow field perturbations in porous media

Many environmental and industrial processes depend on how fluids displace each other in porous materials. However, the flow dynamics that govern this process are still poorly understood, hampered by the lack of methods to measure flows in optically opaque, microscopic geometries. We introduce a 4D microvelocimetry method based on high-resolution X-ray computed tomography with fast imaging rates (up to 4 Hz). We use this to measure flow fields during unsteady-state drainage, injecting a viscous fluid into rock and filter samples. This provides experimental insight into the nonequilibrium energy dynamics of this process. We show that fluid displacements convert surface energy into kinetic energy. The latter corresponds to velocity perturbations in the pore-scale flow field behind the invading fluid front, reaching local velocities more than 40 times faster than the constant pump rate. The characteristic length scale of these perturbations exceeds the characteristic pore size by more than an order of magnitude. These flow field observations suggest that nonlocal dynamic effects may be long-ranged even at low capillary numbers, impacting the local viscous-capillary force balance and the representative elementary volume. Furthermore, the velocity perturbations can enhance unsaturated dispersive mixing and colloid transport and yet, are not accounted for in current models. Overall, this work shows that 4D X-ray velocimetry opens the way to solve long-standing fundamental questions regarding flow and transport in porous materials, underlying models of, e.g., groundwater pollution remediation and subsurface storage of CO2 and hydrogen.

Intensification of low-grade phosphate ore purification using a hydrocyclone with venturi-style inlet

The accumulation of large quantities of low-grade phosphate ore throughout the year occupies land and pollutes the environment. Addressing the challenge of purifying this ore to produce high-grade phosphate is essential for alleviating the shortage of phosphorus resources, making it a pressing research topic. Herein, we propose a hydrocyclone with a venturi-style inlet that combines multiple morphologies to purify low-grade phosphate ore. This innovative design addresses issues with conventional hydrocyclones by reducing short-circuit flow and eliminating circulation flow. Additionally, the new hydrocyclone tackles the overflow entrainment problem of large-density P particles and reduces the possibility of lower-density Si-Mg particles escaping through the underflow pipe, leading to intensified separation performance. The hydrodynamic multiphase flow field characteristics of different hydrocyclone were investigated via CFD simulation to elaborate the reason for the performance intensification. The venturi-style inlet architecture improved the tangential velocity and enhanced the spiral flow field, expanding the length and range of the locus of zero vertical velocity (LZVV) in the primary separation area. This designed hydrocyclone could purify low-grade phosphate ore at lower expenditure and higher performance, with separation efficiency increased from 76% to 92% and precision promoted from 70% to 87% compared to conventional one. This work presented a cheap and efficient technology for purifying low-grade phosphate ore and demonstrated comprehensive potential for the recycling of mineral resources.

Three-dimensional lattice Boltzmann simulations for droplet impact and freezing on ultra-cold superhydrophobic surfaces

Droplet impact and freezing on cold surfaces is a widely encountered multi-physical phenomenon involving droplet deformation and the liquid–solid phase change. Due to its complexity in nature, it is challenging to simulate the three-dimensional (3D) droplet impact and freezing process. Furthermore, due to the limitation of experimental techniques, it is not easy to experimentally investigate the impact of liquid droplets on ultra-cold superhydrophobic surfaces, which is crucial in some applications. Thus, in the present work, a 3D lattice Boltzmann (LB) method is developed to simulate the droplet impact and freezing on an ultra-cold superhydrophobic surface, in which an enhanced cascaded LB method is used to solve the multiphase flow field, and a multi-relaxation-time scheme is applied to solve the liquid–solid phase change model. The previous experimental results are numerically reproduced, proving that the present model can satisfactorily describe the droplet impact and solidification. The surface temperatures have no significant influence on droplet spreading. However, during the droplet retraction, a rim of ice first appears near the three-phase contact line, and then, the droplet bottom will completely solidify into ice. The occurrence of solidification at the bottom of the droplet will lead the droplet to break at a lower impact velocity, which can only be observed at a high Weber number on the room-temperature superhydrophobic surface. In addition, the effects of surface temperatures and Weber numbers on the evolution of spreading factors and space-averaged heat flux are also quantitatively analyzed in detail.

Numerical investigation on entry of an inclined cylinder into water under uniform current and wind

The entry of a circular cylinder into water represents the problem of the coupling of multiphase flow with highly unsteady and nonlinear dynamics. Few studies have examined the influence of the initial angles of inclination of the object on the evolution of the cavity and the multiphase flow field under impact-induced loads in the presence of currents and wind. In this study, we develop a three-dimensional numerical model in OpenFOAM® to simulate and analyze this entire process. An overset mesh technique was used to reproduce the entire process of the entry of a circular cylinder into water as well as the formation, pinch-off, and collapse of the cavity. A comparison between our numerical results and previously published test data from the laboratory confirmed that the proposed numerical model can accurately simulate the dynamic characteristics of the multiphase flow field. The mode and time series of the closure of the cavity varied with the initial angles of inclination of the cylinder, and in turn influenced its translational and rotational characteristics of motion. The pressure, velocity and vortex structures suggest that the evolution and distribution of multiphase flow field for upstream and downstream water entry cases have varied characteristics.

Optimization of a Multiphase Mixed Flow Field in Backfill Slurry Preparation Based on Multiphase Flow Interaction.

The paper analyzes the dynamic behavior during the preparation of cemented backfill slurry by combining the structural performance analysis of the double-shaft mixer and the Euler multiphase flow field computational fluid dynamics model. Considering the interaction between phases and gas phase disturbances, the transient kinetic parameters and the interaction between gas and liquid phases were introduced. According to the modified lift model, the user-defined function of the net lateral lift coefficient and the turbulence energy equation was adjusted. Taking the parameters of flow field velocity, gas phase mixing, uniformity, and turbulent energy dissipation as the evaluation indexes of the mixing effect, the double-shaft mixer at a rotation velocity of 45 rpm and with a blade installation angle of 25° is the optimal design in this study. Experimental tests were carried out and confirmed that the refined two-fluid model of interphase interaction can provide a basis for the performance evaluation of material mixing equipment.