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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

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

Experimental investigation of the flow characteristics of jet pumps for zero flow-ratio conditions

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Journal of Hydrodynamics 2023年第6期35卷 1146-1156页

作者： yun-zhi Liang Jiong Wang Zu-ti Zhang Bin Ji huai-yu cheng Xin-ping Long Key Lab of Jet Theory and New Technology of Hubei Province Wuhan UniversityWuhan430072China School of Power and Mechanical Engineering Wuhan UniversityWuhan430072China State Key Laboratory of Water Resources Engineering and Management Wuhan UniversityWuhan430072China

Experimental research was conducted on the performance curves and the cavity evolution for different flow and geometric parameters in jet pumps for zero flow ratio(ZFR)*** pressure ratio,Pr,flow ratio,qr,were used in place of the conventional performance parameters h,q,to characterize the jet pump flow performance.A super cavitation cavity in the jet pump was observed to fill most of the flow channel,which hindered further increases of the flow rate and increased qr to one,thus,created a critical point on the new P_(r)-q_(r)^(2)*** the critical point,P_(r)was proportional to q_(r)^(2)with a coefficient that was much more sensitive to the area ratio than the relative throat length and the diffusion *** the critical point,the flow rate reached its maximum,the limiting flow rate,which only depended on the total inlet pressure and the area *** total inlet pressure was proportional to the square of the limiting flow rate with a flow coefficient that was only a quadratic function of the area ratio.

关键词： Jet pump performance curve zero flow-ratio super-cavitation

A review of cavitation in tip-leakage flow and its control

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Journal of Hydrodynamics 2021年第2期33卷 226-242页

作者： huai-yu cheng Bin Ji Xin-ping Long Wen-xin huai Mohamed Farhat State Key Lab of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China Hubei Key Laboratory of Waterjet Theory and New Technology Wuhan 430072China Laboratory for Hydraulic Machines Ecole Polytechnique Federale de Lausanne(EPFL)LausanneSwitzerland

The tip-leakage vortex(TLV)cavitation is a challenging issue for a variety of axial hydraulic turbines and pumps from both technical and scientific *** flow characteristics of the TLV cavitation were widely studied in the past decades,but the knowledge about the tip-leakage cavitating flow is still *** present paper reviews the progresses in the researches of the TLV cavitation,including the numerical methods for the TLV cavitation,the flow characteristics of the TLV,the influences of the TLV cavitation on the local flow field and the control strategies of the TLV *** is indicated that the non-condensable gas may play an important role in the development of the TLV cavitation,and this fact should be considered during a careful simulation of the TLV *** is also suggested that the development of the TLV cavitation will significantly influence the distributions of the vorticity and the turbulence kinetic *** to the complexity of the TLV cavitation,it is still an open question how to suppress the TLV cavitation in a simple but effective ***,based on these understandings,some advanced topics for the future work are suggested to further promote the study of the TLV cavitation,for a deeper knowledge about the TLV cavitation.

关键词： Cavitation tip-leakage vortex(TLV) cavitation model flow control nuclei

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

Transition-Metal-Free Allylic Defluorination Cross-Electrophile Coupling Employing Rongalite

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Chinese Journal of Chemistry 2024年第12期42卷 1360-1366页

作者： Xiang-Long Chen Chun-Yan Wu Dong-Sheng Yang Bo-cheng Tang huai-yu Wang Zhi-cheng yu Anling Li Yan-Dong Wu An-Xin Wu National Key Laboratory of Green Pesticide International Joint Research Center for Intelligent Biosensor Technology and HealthCollege of ChemistryCentral China Normal UniversityWuhanHubei 430079China state Key Laboratory of Chemical Biology and Drug Discovery Department of Applied Biology and Chemical Technology The HongKong Polytechnic UniversityKowloonHong Kong SARChina Department of Clinical Laboratory Center for Gene Diagnosisand Program of Clinical Laboratory MedicineZhongnan Hospital of Wuhan UniversityWuhanHubei 430062China

Comprehensive Summary The conversion of CF3-alkenes to gem-difluoroalkenes using reductive cross-coupling strategy has received much attention in recent years,however,the use of green and readily available reducing salt to mediate these reactions remains to be *** this work,a concise construction of gem-difluoroalkenes,which requires neither a catalyst nor a metal reducing agent,was ***,a safe and inexpensive industrial product,was employed as both a radical initiator and *** procedure was compatible with both linear and cyclic diaryliodonium salts,enabling a wide variety of substrates(>70 examples).The utility of this approach was demonstrated through gram-scale synthesis and efficient late-stage functionalizations of anti-inflammatory drugs.

关键词： Defluoroarylation Transition metal free gem-Difluoroalkenes Rongalite Single electron transfer C-C coupling Redox reactions Cross-coupling

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

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