International Journal of Multiphase Flow最新文献

{"title":"Transient rising of oxygen bubbles in a fast varying gravity","authors":"Anne Mongruel ,&nbsp;Gurunath Gandikota ,&nbsp;Denis Chatain ,&nbsp;Alain Mailfert ,&nbsp;Prisca Andriamananjaona ,&nbsp;Daniel Beysens","doi":"10.1016/j.ijmultiphaseflow.2023.104560","DOIUrl":"10.1016/j.ijmultiphaseflow.2023.104560","url":null,"abstract":"<div><p><span>We report experiments on the transient motion of an oxygen bubble rising in liquid oxygen in a fast varying magneto-gravitational acceleration. In the set-up, a strong magnetic field gradient is applied, which creates in bulk oxygen a body force opposed to its weight. When this gravity compensation is suddenly suppressed, the resulting apparent gravity increases within a fraction of a second from 0 </span><span><math><msub><mrow><mi>g</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> to 0.4 <span><math><msub><mrow><mi>g</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> (where <span><math><msub><mrow><mi>g</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> is the terrestrial gravitational acceleration). Oxygen bubbles of diameters ranging from 6 mm to 18 mm rise rapidly in the liquid by buoyancy, for values of Galilei and Bond numbers rarely reached with common fluids in terrestrial gravity. The shape of the bubble interface is initially ellipsoidal and evolves toward more complicated shapes during the motion. The time-dependent rising velocity of the bubble is measured during the fast variation of gravity. A comparison of the transient bubble dynamics with classical results obtained in a constant gravity environment enables the time scale of the gravity variation to be precisely quantified.</p></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"168 ","pages":"Article 104560"},"PeriodicalIF":3.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"54451258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Particle dispersion over side-by-side square cylinders: Proximity interference effects","authors":"Harshal P. Mahamure ,&nbsp;Vagesh D. Narasimhamurthy ,&nbsp;Lihao Zhao","doi":"10.1016/j.ijmultiphaseflow.2023.104571","DOIUrl":"10.1016/j.ijmultiphaseflow.2023.104571","url":null,"abstract":"<div><p><span>This paper investigates the dispersion of tiny inertial particles in the two-dimensional laminar wake from a pair of square cylinders placed side-by-side to each other. The flow Reynolds number (defined based on the cylinder size </span><span><math><mi>h</mi></math></span> and uniform inflow velocity <span><math><msub><mrow><mi>U</mi></mrow><mrow><mi>c</mi></mrow></msub></math></span>) in our study is fixed at 75. The wake pattern resulting from the interaction between vortices shed from individual cylinders depends on the cross-stream spacing between the cylinders, i.e. spacing ratio <span><math><mrow><mi>s</mi><mo>/</mo><mi>h</mi></mrow></math></span>. We examine the effect of varying the cross-stream spacing between the cylinders on the body impaction and dispersion of particles in the wake flow over a range of their responses. Three different spacing ratios, <span><math><mrow><mi>s</mi><mo>/</mo><mi>h</mi></mrow></math></span><span> = 0.3, 2, and 4 are considered. We find that the impaction efficiency of Stokes number </span><span><math><mrow><mi>S</mi><mi>t</mi></mrow></math></span> = 0.1 particles is not sensitive to the spacing ratio. However, the impaction efficiency of <span><math><mrow><mi>S</mi><mi>t</mi></mrow></math></span><span> = 1 and 10 particles is dependent on the spacing ratio and increases with the latter. We illustrate how the distribution and clustering of representative inertial particles (i.e., with Stokes number unity) evolve over a vortex shedding cycle uniquely due to the wake flow in each spacing ratio configuration and explain the physical mechanism of particle clustering using backward tracking. The non-uniform clustering of particles with different responses to the wake flow in each spacing ratio configuration is analyzed using the Voronoï diagrams. The spacing ratio effects on the dispersion of particles are quantified in terms of mean statistical quantities such as mean local concentration, clustering intensity, and velocity statistics. The local concentration of </span><span><math><mrow><mi>S</mi><mi>t</mi></mrow></math></span><span><span> = 1 and 10 particles at streamwise<span> positions away from cylinders is significantly influenced by the wake flow behavior governed by the choice of the spacing ratio. Further, the combined effect of gravity and hydrodynamic drag forces on the impaction and clustering behavior of particles is reported, where the </span></span>Froude number </span><span><math><mrow><mi>F</mi><mi>r</mi><mo>=</mo><mn>0</mn><mo>.</mo><mn>32</mn></mrow></math></span>. In all the cases, particles exhibit ballistic behavior, showing a significantly reduced tendency to form clusters and a drastic increase in the impaction efficiency.</p></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"168 ","pages":"Article 104571"},"PeriodicalIF":3.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46973916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A model for the momentum flux parameters of the 1D Two-Fluid Model in vertical annular flows: Linear stability and numerical analysis","authors":"Rodrigo Luís F. Castello Branco ,&nbsp;João N.E. Carneiro ,&nbsp;Angela O. Nieckele","doi":"10.1016/j.ijmultiphaseflow.2023.104563","DOIUrl":"10.1016/j.ijmultiphaseflow.2023.104563","url":null,"abstract":"<div><p>The 1D Two-Fluid model is based on an area average process of the time and phase averaged Two-Fluid conservation equations to render the model tractable for industrial scale problems. Due to the averaging processes, the loss of information renders the standard model ill-posed for certain configurations, i.e., short wavelengths disturbances are amplified at an unbounded rate and unphysical solutions are obtained. Closure relations play a key role in this problem, since they are required to close the 1D system and they reintroduce missing physical parameters that may stabilize the flow and render the model well-posed. Two formulations for the liquid momentum flux parameter (<span><math><msub><mi>C</mi><mi>L</mi></msub></math></span>) for vertical annular flows are proposed based on local velocities distributions. Differential viscous Kelvin-Helmholtz and von Neumann stability analyses are performed to evaluate the proposed <span><math><msub><mi>C</mi><mi>L</mi></msub></math></span> formulations and three dynamic pressure models. Results have shown that dynamic pressure closure models introduce a small additional amount of damping into the growth rate curves, without a significant change in the hyperbolicity of the system. On the other hand, the novel <span><math><msub><mi>C</mi><mi>L</mi></msub></math></span> models can guarantee well posedness of the linear system by introducing a growth rate plateau, blocking the unbounded growth of instabilities. Numerical simulations were also performed, and numerical dispersion relations were extracted from the results showing good agreement against LST data, validating the methodology. The novel <span><math><mrow><msub><mi>C</mi><mi>L</mi></msub><mspace></mspace></mrow></math></span>models are evaluated against a large experimental database from the literature, showing that the proposed models outperform the standard constant <span><math><msub><mi>C</mi><mi>L</mi></msub></math></span> values for both pressure drop and liquid film thickness.</p></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"168 ","pages":"Article 104563"},"PeriodicalIF":3.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"54451272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A three-phase Eulerian–Lagrangian model to simulate mixing and oxygen transfer in activated sludge treatment","authors":"Boyang Chen,&nbsp;Bruño Fraga,&nbsp;Hassan Hemida","doi":"10.1016/j.ijmultiphaseflow.2023.104555","DOIUrl":"10.1016/j.ijmultiphaseflow.2023.104555","url":null,"abstract":"<div><p><span><span>We introduce a novel modelling tool for the activated sludge process (ASP) based on large-eddy simulation and multiphase Eulerian–Lagrangian coupling. Aeration-driven sludge activation is a key part of </span>wastewater treatment<span> and represents the vast majority of its energy consumption. Our model allows interaction among the liquid (wastewater), solid (sludge) and gas (air bubbles) phases, to provide insight on the fluid dynamics<span> taking place during ASP. The model uses an Eulerian–Lagrangian point-particle algorithm that respects the discrete nature of both sludge flocs and air bubbles. Four-way coupling is implemented, where the interaction between solid particles is handled by a soft-sphere collision model. The analysis was focused on quantifying the Oxygen transfer from gas to liquid<span> to solid, i.e., the conditions for aerobic bacteria activation. Such transfer is complex due to the dispersed nature of the gas and solid phases and the turbulent mixing occurring in the tank. Unlike box-modelling approaches, our three-dimensional model describes the evolution in space and time of the concentrations of these species and the Oxygen exchange, without a priori assumptions on the nature of the mixture. The model was validated versus experimental data using the interphase exchange of Oxygen as the key parameter, exhibiting in all cases an excellent agreement with measurements that qualitatively improves Eulerian–Eulerian approaches in five different tests. Subsequently our model was used to simulate a realistic scenario within the </span></span></span></span>aeration basin<span> of a wastewater plant and explore its results across a wide parameter range (aerator distribution, dissolved Oxygen levels<span><span>, air flow rate, sludge size, bubble size). This allow us the explore the time evolution of the </span>activation process and therefore test its performance versus the air flow rate injected (hence, energy). Our results indicate that the initial dissolved Oxygen levels within the basin (related to weather conditions and aeration frequency) are critical for sludge activation, with initial anoxic conditions being very taxing. For a given flow rate, bubble screens (i.e, more aerators) provide significantly better performance. Finally, we compare model estimations of bacterial Oxygen uptake with field data obtained from real-life ASP in wastewater plants, finding a good agreement. We therefore present to the community a reliable and extendable model that solves the fluid mechanics and the basic eco-hydraulics of the three-phase system encountered in wastewater plants, with minimal empirical inputs. This is a valuable and precise tool to test the operations and design of ASP and similar processes.</span></span></p></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"168 ","pages":"Article 104555"},"PeriodicalIF":3.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47487402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical study of liquid jet and shock wave induced by two-bubble collapse in open field","authors":"Xiaobin Yang ,&nbsp;Cheng Liu ,&nbsp;Jingqi Li ,&nbsp;Yuxiao Yang ,&nbsp;Min Zhao ,&nbsp;Changhong Hu","doi":"10.1016/j.ijmultiphaseflow.2023.104584","DOIUrl":"10.1016/j.ijmultiphaseflow.2023.104584","url":null,"abstract":"<div><p>The shock waves and high-speed jets induced by the violent collapse of bubbles can cause serious damage to nearby structures. To fully understand the shock wave and jet characteristics induced by bubble-bubble interaction, we developed a diffuse-interface method for the simulation of compressible two-phase flow, which combined interface compression technique with interface sharpening technique to keep the sharpness of the shock wave and phase interface. The thermodynamically consistent five-equation model was improved using interface compression technique to maintain a constant thickness of the phase interface. To further suppress numerical dissipation, the high-order scheme WENO (Weighted Essentially Non-Oscillatory) and interface sharpening function THINC (Tangent of Hyperbola for INterface Capturing) were used for the flux reconstruction at the grid boundary to ensure that the total variation at the cell boundary was minimized (Boundary Variation Diminishing, BVD), thus the spatial reconstruction scheme, named WENO-THINC-BVD, was developed. Moreover, we extended the present method to a block-structured adaptive mesh refinement framework to improve grid resolution and save computing resources. Numerical results of several benchmark tests fully demonstrated the advantages of the present method in simulating complex compressible flows containing shock-shock and shock-interface interactions. Based on the present high-fidelity numerical methods, we investigated the shock wave and liquid jet induced by the two-bubble interaction in an open space. A phase diagram of the liquid jet propagation direction as a function of the initial bubble pressure and the inter-bubble distance was summarized. Finally, according to the bubble-bubble interaction process, an empirical formula for the collapse strength and another for the attenuation of shock waves were developed.</p></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"168 ","pages":"Article 104584"},"PeriodicalIF":3.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46519774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Scalar transport and nucleation in quasi-two-dimensional starting jets and puffs","authors":"You-An Lee ,&nbsp;Detlef Lohse ,&nbsp;Sander G. Huisman","doi":"10.1016/j.ijmultiphaseflow.2023.104556","DOIUrl":"10.1016/j.ijmultiphaseflow.2023.104556","url":null,"abstract":"<div><p>We experimentally investigate the early-stage scalar mixing and transport with solvent exchange in a quasi-two-dimensional (quasi-2D) jet. We inject an ethanol/oil mixture upward into quiescent water, forming quasi-2D turbulent buoyant jets and triggering the ouzo effect with initial Reynolds numbers, <span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>=</mo><mn>420</mn><mo>,</mo></mrow></math></span> <span><math><mrow><mn>840</mn><mo>,</mo></mrow></math></span> and 1680. We study two different modes of fluid supply: continuous injection to study a starting jet and finite volume injection to study a puff. While both modes start with the jet stage, the puff exhibits different characteristics in transport, entrainment, mixing, and nucleation, due to the lack of continuous fluid supply. We also inject a dyed ethanol solution as a passive scalar reference case, such that the effect of nucleation for the ethanol/oil mixture can be disentangled.</p><p>For the starting jets, the total nucleated mass from the ouzo mixture seems very similar to that of the passive scalar total mass, indicating a primary nucleation site slightly above the virtual origin above the injection needle, supplying the mass flux like the passive scalar injection. With continuous mixing above the primary nucleation site, the mildly increasing nucleation rate suggests the occurrence of secondary nucleation throughout the entire ouzo jet.</p><p>For the puffs, we show that the puff with the smallest <span><math><mrow><mi>R</mi><msub><mrow><mi>e</mi></mrow><mrow><mn>0</mn></mrow></msub></mrow></math></span> propagates the fastest and its entrainment lasts the longest. We attribute the superior performance to the buoyancy effect, which transforms a turbulent puff into a turbulent thermal, and has been proven to have stronger entrainment. Although the entrainment and nucleation reduce drastically when the injection stops, the mild mixing still leads to non-zero nucleation rates and the reduced decay of the mean puff concentrations for the ouzo mixture.</p><p>Adapting the theoretical framework established in Landel et al. (2012b) for quasi-2D turbulent jets and puffs, we successfully model the transport of the horizontally-integrated concentrations for the passive scalar. The fitted advection and dispersion coefficients are then used to model the transport of the ouzo mixture, from which the spatial–temporal evolution of the nucleation rate can be extracted. The spatial distribution of the nucleation rate sheds new light on the solvent exchange process in transient turbulent jet flows.</p></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"168 ","pages":"Article 104556"},"PeriodicalIF":3.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0301932223001775/pdfft?md5=987b68f0089dde47678b3cb7d4b81444&pid=1-s2.0-S0301932223001775-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47595699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Combined optical connectivity and optical flow velocimetry measurement of interfacial velocity of a liquid jet in gas crossflow","authors":"Tianyi Wang,&nbsp;Yannis Hardalupas","doi":"10.1016/j.ijmultiphaseflow.2023.104581","DOIUrl":"10.1016/j.ijmultiphaseflow.2023.104581","url":null,"abstract":"<div><p>Liquid jet in crossflow (LJIC) is a process in which a high-speed gas crossflow deforms and shears a continuous liquid flow into tiny droplets. This study quantifies the liquid surface motion of LJIC during the primary breakup process, which has not been quantified due to the optical limitation close to the nozzle exit. The interfacial velocity of a breaking liquid jet indicates the local interaction of the gas and liquid flows and determines the initial velocity of the stripped droplets. The local interfacial liquid velocities of LJIC have only been estimated from theoretical and computational studies, which have not been evaluated from measurements. Optical Connectivity (OC) introduces a laser beam through an atomiser nozzle and relies on total internal reflection at the liquid interface to propagate the laser light inside the continuous liquid to record the instantaneous features of the interface of the continuous liquid during the primary atomisation at the near nozzle region through imaging of the emitted fluorescent intensity from the liquid flow. The current study combines Optical Connectivity with Optical Flow Velocimetry (OFV) to quantify the time-dependent, local interfacial velocity of the liquid interface structures of the LJIC for gas Weber numbers between 14.9 - 112.6 and liquid-to-gas momentum ratios between 2.1 - 36.4. The combined OC-OFV measurements of the spatial distribution of the mean and fluctuating values of the different components of the liquid interfacial velocity of LJIC demonstrate how the gaseous shear and liquid jet geometry interact to influence the atomisation process.</p></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"168 ","pages":"Article 104581"},"PeriodicalIF":3.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S030193222300201X/pdfft?md5=7bb0ccba4adc3017afb8acc846217e60&pid=1-s2.0-S030193222300201X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41813875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A three-dimensional non-orthogonal multiple-relaxation-time phase-field lattice Boltzmann model for multiphase flows at large density ratios and high Reynolds numbers","authors":"Geng Wang ,&nbsp;Junyu Yang ,&nbsp;Timan Lei ,&nbsp;Jin Chen ,&nbsp;Qian Wang ,&nbsp;Kai H. Luo","doi":"10.1016/j.ijmultiphaseflow.2023.104582","DOIUrl":"10.1016/j.ijmultiphaseflow.2023.104582","url":null,"abstract":"<div><p>This study proposes a three-dimensional non-orthogonal multiple-relaxation-time (NMRT) phase-field multiphase lattice Boltzmann (PFLB) model within a recently established unified lattice Boltzmann model (ULBM) framework [Luo et al., Phil. Trans. R. Soc. A 379, 20200397, 2021]. The conservative Allen-Cahn equation and the incompressible Navier-Stokes (NS) equations are solved. In addition, a local gradient calculation scheme for the order parameter of the Allen-Cahn equation is constructed with the non-equilibrium part of the distribution function. A series of benchmark cases are conducted to validate the proposed model, including the two-phase Poiseuille flow, Rayleigh-Taylor instability, binary liquid/metal droplet collision, and a bubble rise in water. The present simulation results are in good agreement with existing simulation and experimental data. In the simulation of the co-current two-phase Poiseuille flow, the present model is proven to resolve the discontinuity at the phase interface and provide accurate results at extremely high density ratios (i.e., up to <span><math><msup><mrow><mn>10</mn></mrow><mn>6</mn></msup></math></span>). Finally, the proposed model is adopted to simulate two challenging cases: (1) water droplet splashing during its impacting on a thin liquid film and (2) liquid jet breakup. The simulation results demonstrate an excellent agreement with previous experimental results, both qualitatively and quantitatively. In these simulations, the Weber number and Reynolds number reach 10⁵ and 6000, respectively, and the viscosity can be as low as <span><math><mrow><mo>∼</mo><msup><mrow><mn>10</mn></mrow><mrow><mo>−</mo><mn>4</mn></mrow></msup></mrow></math></span>, in the lattice unit.</p></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"168 ","pages":"Article 104582"},"PeriodicalIF":3.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0301932223002021/pdfft?md5=7bbeada99167d443c149484694de5cad&pid=1-s2.0-S0301932223002021-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41845316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical study on coupled flow characteristics of a gas-solid two-phase jet in a supersonic crossflow","authors":"Hongming Ding ,&nbsp;Changfei Zhuo ,&nbsp;Hanyu Deng ,&nbsp;Wenjun Hu ,&nbsp;Xiong Chen","doi":"10.1016/j.ijmultiphaseflow.2023.104583","DOIUrl":"10.1016/j.ijmultiphaseflow.2023.104583","url":null,"abstract":"<div><p>In this study, the Eulerian-Lagrangian scheme coupled with the gas-solid two-phase Reynolds-average Navier-Stokes (RANS) method was used to study the airflow and particles flow characteristics of particles of different diameters injected into a supersonic flow field by a sonic jet. The results show that introducing small particles has little effect on the flow field. When the particle diameter is 1e-6 m, most particles are mainly distributed in the shear layer, and some parts of the particles are sucked into the surface trailing counter-rotating vortex pairs (TCVP) and the wall boundary layers by the airflow. The introduction of large diameter particles hinders the jet's development, reduces the Mach disk's height, and makes the counter-rotating vortex pair (CVP) closer to the wall. This leads to a decrease in the streamwise velocity and an increase in the wall-normal velocity near the wall downstream of the jet. The streamwise velocity increases and the wall-normal velocity decreases at the far wall downstream of the jet. At the same time, it exacerbates the Kelvin-Helmholtz (K-H) instability in the shear layer on the windward side of the jet, forming a large-scale coherent structure between the shear layer and crossflow. The penetration depth and diffusion range of particles increase with particle diameter and density, and the velocity decreases with particle diameter increase by comparing the trajectories of particles with different diameters and densities.</p></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"168 ","pages":"Article 104583"},"PeriodicalIF":3.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44492520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A computational study of the influence of evaporation and molecular transport on temporally-evolving droplet-laden plane jets","authors":"Luis Antonio Carbajal Carrasco,&nbsp;Zakaria Bouali,&nbsp;Arnaud Mura","doi":"10.1016/j.ijmultiphaseflow.2023.104545","DOIUrl":"10.1016/j.ijmultiphaseflow.2023.104545","url":null,"abstract":"<div><p>Numerical simulations of temporally-evolving droplet-laden plane jets are performed in conditions relevant to rocket main engines fed with liquid oxygen (LOx) and gaseous methane (CH₄<span><span><span><span>). The computations are performed using a direct numerical simulation (DNS) solver with the liquid phase represented within the discrete particle simulation (DPS) framework. Considering the multiplicity of the physical phenomena that are involved in such conditions – e.g., </span>atomization, dispersion, evaporation – a progressive and phenomenological methodology is retained to proceed with a complexity-increasing set of computations. Thus, the development of a purely gaseous jet is first studied with the corresponding set of data providing a reference or </span>baseline condition. Then, other conditions are considered to analyze the influence of (i) </span>liquid droplet evaporation and (ii) molecular mixing processes as described by two distinct multicomponent transport models. The analysis of the obtained results shows that both evaporation and molecular transport representation play a crucial role in the plane jet development and may drastically alter its characteristics before ignition and subsequent combustion stabilization may take place. Finally, the obtained results also unambiguously put into evidence the influence of the Lewis number onto the vaporization rate.</span></p></div>","PeriodicalId":339,"journal":{"name":"International Journal of Multiphase Flow","volume":"168 ","pages":"Article 104545"},"PeriodicalIF":3.8,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45345385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}