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Temporal and spatial characteristics of monopole acoustic energy dominated by unsteady thermodynamic cavitating flow

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Journal of Hydrodynamics 2021年第4期33卷 867-871页

作者： Xin-cheng Wang Xiao-rui Bai huai-yu cheng Bin Ji State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China

The acoustic propagation characteristics of the cavitating flow are essential for the noise suppression, but were not well studied. In the current paper, a new technique concerning the propagation path of the monopole acoustic energy is presented and two typical thermodynamic cavitation modes (the inertial and thermal modes) are selected to investigate the effect of the cavity shedding dynamics on the acoustic propagation path. In the inertial mode, the temporal variation and the spatial distributions of the monopole acoustic energy as well as the divergence of the monopole acoustic pressure are both more powerful and concentrated than that in the thermal mode. The acoustic propagation path in the thermal mode strictly satisfies the feature of the convective amplification, while there exists another propagation direction close to the normal direction of the foil surface in the inertial mode. Furthermore, the occurrence of the normal direction propagation will make the path deviate from the convective direction.

关键词： Thermodynamic cavitation acoustic propagation path hydroacoustic inertial mode thermal mode

Some notes on numerical investigation of three cavitation models through a verification and validation procedure

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Journal of Hydrodynamics 2023年第1期35卷 185-190页

作者： Lin-feng Deng yun Long huai-yu cheng Bin Ji State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China Wuhan Second Ship Design and Research Institute Wuhan430064China

The present paper investigates the turbulent cavitating flow around the Clark-Y hydrofoil with special emphasis on the influence of cavitation models by verification and validation(V&V)*** solver coupled with the three major cavitation models(i.e.,Zwart-Gerber-Belamri,Schnerr and Sauer and full cavitation model,which are abbreviated to ZGB model,SS model and FC model respectively)is employed in this *** results indicate that the three cavitation models can properly reproduce the cavitation *** model and SS model give better prediction in the overall cavitation *** model exhibits an obvious under-estimation for the sheet cavity,and the predicted volume fraction is closely related to the turbulent *** verification and validation procedure is involved to quantitatively assess the accuracy of these three cavitation *** is indicated that the V&V procedure is suitable for the unsteady cavitating *** errors estimate is robust and conservative within the cavitation region,while gets closer to zero in the no-cavitation *** addition,ZGB model exhibits the highest overall accuracy among the three models,which further verifies its wide applicability.

关键词： Cavitating flow cavitation model verification and validation(V&V) error estimate

Large eddy simulation of the transient cavitating vortical flow in a jet pump with special emphasis on the unstable limited operation stage

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Journal of Hydrodynamics 2020年第2期32卷 345-360页

作者： Xin-ping Long Dan Zuo huai-yu cheng Bin Ji Hubei Key Laboratory of Waterjet Theory and New Technology School of Power and Mechanical EngineeringWuhan UniversityWuhan430072China Key Laboratory of Transients in Hydraulic Machinery Ministry of EducationWuhan UniversityWuhan430072China State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China

This paper studies the unsteady three-dimensional cavitating turbulent flow in a jet ***,thefocus is on the unstable limited operation stage,and both the computational and experimental methods are *** the experiments,the distribution of the wall pressure,as well as the evolution of cavitation over time,are obtained for a jet *** is carried out using the large eddy simulation,combined with a mass transfer cavitation *** numerical results are compared with the experimental results,including the fundamental performances(the pressure ratio h and the efficiencyη),as well as the wall pressure *** the experimental and computational results indicate that the evolution of the cavitation over time in a jet pump is a quasi-periodic process during the unstable limited operation *** annular vortex cavitation inception,development and collapse predicted by the large eddy simulation agree fairly well with the experimental ***,the relationship between the cavitation and the vortex structure is discussed based on the numerical results,and it is shown that the development of the vortex structures in the jet pump is closely related to the evolution of the *** cavitation-vortex interaction is thoroughly analyzed based on the vorticity transport *** analysis reveals that the cavitation in a jet pump dramatically influences the distribution and the production of the *** process of the annular cavitation inception,development,and collapse involves a significant increase of the vorticity.

关键词： Cavitation jet pump large eddy simulation vortex structure vorticity transport equation

Numerical assessment of the erosion risk for cavitating twisted hydrofoil by three methods

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Journal of Hydrodynamics 2021年第4期33卷 698-711页

作者： Ting-ting Lei huai-yu cheng Bin Ji Xiao-xing Peng State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China National Key Laboratory on Ship Vibration and Noise China Ship Scientific Research CenterWuxi214082China

In this paper, the large eddy simulation (LES) method in conjunction with the Zwart cavitation model is adopted for the assessment of the erosion risk on a hydrofoil surface. The numerical results are in good agreement with the experiments. On this basis, three methods, namely the intensity function method (IFM), the time-averaged aggressiveness indicators (TAIs) and the gray level method (GLM), are applied for the assessment of the erosion risk. It is shown that the erosion intensity index of the IFM is extremely sensitive to the artificially selected thresholds, which greatly limits the application of the method. The erosion risk predicted by four indicators in the TAIs does not agree well with the experimental results. Further analysis demonstrates that the GLM using the instantaneous pressure field is relatively satisfactory, which can provide a reasonable assessment of the erosion and is not very sensitive to the artificially selected thresholds. To further improve the accuracy of the GLM for the erosion risk prediction, the time-average pressure field is adopted in the GLM for the erosion evaluation. It is suggested that the erosion assessment by using the time-averaged pressure field is in better agreement with the experimental results when compared with that by using the instantaneous pressure field.

关键词： Cavitating flow erosion numerical simulation threshold selection

LES method of the tip clearance vortex cavitation in a propelling pump with special emphasis on the cavitation-vortex interaction

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Journal of Hydrodynamics 2020年第6期32卷 1212-1216页

作者： cheng-zao Han Shun Xu huai-yu cheng Bin Ji Zhi-yuan Zhang State Key Lab of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China Marine Design and Research Institute of China Shanghai200011China

The turbulent cavitating flow around the propelling pump tip clearance is numerically simulated using the large eddy simulation(LES)method coupled with the Zwart-Gerber-Belamri(ZGB)cavitation model to investigate the cavitation-vortex interaction *** calculated cavitation structures around the blades are in a remarkable agreement with the experimental *** distributions of the tip clearance vortex under two cavitation conditions are obtained and *** results show that the cavitation development enhances the vorticity generation and the flow unsteadiness around the tip clearance of a propelling *** are basically located around the cavitation areas,particularly in the tip clearance region,during the *** relative vorticity transport equation is applied for the cavitating turbulent flows and it is further indicated that the vortex stretching term makes the main contribution in the vortex production,and the baroclinic torque and dilation terms are important source terms for the vorticity generation in the cavitating *** addition,the viscous diffusion term and the Coriolis force term are significant in modifying the vorticity field inside the blade tip clearance.

关键词： Tip-clearance cavitation propelling pump large eddy simulation(LES) vorticity transport equation

Some notes on numerical simulation of the turbulent cavitating flow with a dynamic cubic nonlinear sub-grid scale model in OpenFOAM

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Journal of Hydrodynamics 2020年第4期32卷 790-794页

作者： Zi-yang Wang Xian-bei Huang huai-yu cheng Bin Ji State Key Laboratory of Water Resources and Hydropower Engineering Science School of Power and Mechanical EngineeringWuhan UniversityWuhan 430072China College of Electrical Energy and Power EngineeringYangzhou UniversityYangzhou 225127China

The accuracy of large eddy simulation(LES)is highly dependent on the performance of sub-grid scale(SGS)*** the present paper,a dynamic cubic nonlinear sub-grid scale model(DCNM)proposed by Huang et *** implemented for the simulation of unsteady cavitating flow around a 3-D Clark-Y hydrofoil in *** performance in predicting the evolution of cloud cavitation is discussed in *** simulation with a linear model,the dynamic Smagorinsky model(DSM),is also conducted as a *** results with DCNM show a better agreement with the available experimental *** comparison between DCNM and DSM further suggests that the DCNM is able to predict the backscatter more precisely,which is an important feature in *** characteristics of DCNM is analyzed to account for its advantages in the prediction of unsteady cloud cavitation as *** results reveal that it is the nonlinear terms of DCNM that makes DCNM capture sub-grid scale vortices better and more suitable for studying the transient behaviors of cloud cavitation than DSM.

关键词： Cavitation large eddy simulation(LES) nonlinear sub-grid scale model OpenFOAM

Cavitation research with computational fluid dynamics:From Euler-Euler to Euler-Lagrange approach

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Journal of Hydrodynamics 2024年第1期36卷 1-23页

作者： Bin Ji Zi-yang Wang huai-yu cheng Rickard E.Bensow State Key Laboratory of Water Resources Engineering and Management Wuhan UniversityWuhan430072China Department of Mechanics and Maritime Sciences Chalmers University of TechnologyGothenburgSweden

Unsteady cavitating flow often contains vapor structures with a wide range of different length scales,from micro-bubbles to large cavities,which issues a big challenge to precisely investigate its evolution mechanism by computational fluid dynamics(CFD)*** present work reviews the development of simulation methods for cavitation,especially the emerging Euler-Lagrange ***,the progress of the numerical investigation of hot and vital issues is discussed,including cavitation inception,cloud cavitation inner structure and its formation mechanism,cavitation erosion,and cavitation *** is indicated that the Euler-Lagrange method can determine cavitation inception point *** cloud cavitation,the Euler-Lagrange method can reveal the source of microbubbles and their distribution law inside the shedding *** method also has advantages and great potential in assessing cloud cavitation-induced erosion and *** the ever-growing demands of cavitation simulation accuracy in basic research and engineering applications,how to improve the Euler-Lagrange method’s stability and applicability is still an open *** further promote the application of this advanced CFD simulation technology in cavitation research,some key issues are to be solved and feasible suggestions are put forward for further work.

关键词： numerical simulation Euler-Euler method Euler-Lagrange method bubble dynamicsgy,Gothenburg,Sweden

Numerical simulation of multi-scale cavitating flow with special emphasis on the influence of vortex on micro-bubbles

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Journal of Hydrodynamics 2022年第6期34卷 1032-1043页

作者： Ming-zhe Zhou Zi-yang Wang Xiao-rui Bai huai-yu cheng Bin Ji State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan430072China

A multi-scale Euler-Lagrange method is applied in the current paper to investigate the characteristics of turbulent cloud cavitating flow around a Clark-Y hydrofoil,in which macroscopic cavitating structures are simulated by volume of fluid(VOF)approach,while micro-scale bubbles are modelled based on Rayleigh-Plesset equation and bubble motion *** numerical results are in reasonable agreement with the available experiments,and the transition between multi-scale structures is captured *** evolution of microscopic bubble behaviors is statistically *** one typical cycle,numbers and Sauter mean radius of the bubbles show a similar variation tendency which both sharply spike to their maxima after the breakup of the sheet cavity,and then decrease continuously to their minima before the next *** bubbles are mainly concentrated at the tail of the attached cavity,in front of the cloud cavity and in the region quite close to the hydrofoil suction ***,vortices are extracted to account for the micro-scale *** is found that intense vortices aggravate turbulence fluctuation,thus spalling cavity to generate massive micro ***,the vortices provide microscopic bubbles low pressure and detain them so that numerous bubbles are able to *** effects are remarkable after the breakup of attached sheet cavity,owing to the violent vortices *** the contrary,when sheet cavity develops,the flow field becomes comparatively stable since the strong vortices travel *** micro-scale bubbles are produced,and their volume is generally small.

关键词： Cloud cavitation Euler-Lagrange method bubble-vortex interaction bubble dynamics

Spatial and spectral investigation of turbulent kinetic energy in cavitating flow generated by Clark-Y hydrofoil

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Journal of Hydrodynamics 2020年第1期32卷 175-178页

作者： Xiao-rui Bai huai-yu cheng Bin Ji Xin-ping Long State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China Science and Technology on Water Jet Propulsion Laboratory Shanghai 200011China

In the present paper,the turbulent cavitating flow generated by a Clark-Y hydrofoil is investigated by large eddy simulation(LES)combined with Zwart-Gerber-Belamri(ZGB)cavitation *** order to shed light on the influence of cavitation on turbulent energy distribution among scales,energy spectrum obtained from the three-dimensional velocity field is firstly applied to turbulent cavitating *** and spectral distributions of turbulent kinetic energy are studied for both non-cavitating flow and cavitating *** is found to have a significant effect on the original turbulent flow by inducing more large-scale turbulent *** energy spectrum of cloud cavitating flow also experiences a periodic evolution as cavitation develops,and a large amount of turbulent kinetic energy is found to generate as the first shedding,cutoff and second shedding of cavities happen.

关键词： Cavitating flow energy spectrum large eddy simulation(LES) turbulent kinetic energy cloud cavitation