The design method of small-flow high-head centrifugal-vortex pump was presented. This pump, configured with inducer, complex-centrifugal impeller and open-vortex impeller, was put forward to deliver gas-liquid two-pha...The design method of small-flow high-head centrifugal-vortex pump was presented. This pump, configured with inducer, complex-centrifugal impeller and open-vortex impeller, was put forward to deliver gas-liquid two-phase mixture. An HTB-5/60 type sample pump was developed and tested on a closed-loop test rig. Experimental studies on performance and cavitation tests for gas-liquid two-phase mixture were carried out compared with pure-water experimental results. Also the effect of gas phase on pump was analyzed and discussed. The experimental results show that performance and cavitation characteristics of the sample purnp deteriorates progressively with increasing volume fraction of gas. When the total capacity Qm is between 4.5 m^3·h^-1 and 6 m^3·h^-1 and the gas flow rate qg below 0.66 m^3·h^-1, or qg/Qm is lower than 15%, the characteristic curves are approximately parallel to those in pure water test, but the performance deteriorates sharply until an abrupt flow-cutting at a critical volume fraction of gas. This pump is found suitable for transporting gas-liquid two-phase mixture when working around rated capacity of 5 m^3·h^-1 with qglQm below 15%.展开更多
In this paper, recent measurements of tip vortex flow with and without cavitation carried out in Cavitation Mechanism Tunnel of China Ship Scientific Research Center（CSSRC） are presented. The elliptic hydrofoil with...In this paper, recent measurements of tip vortex flow with and without cavitation carried out in Cavitation Mechanism Tunnel of China Ship Scientific Research Center（CSSRC） are presented. The elliptic hydrofoil with section NACA 662-415 was adopted as test model. High-speed video（HSV） camera was used to visualize the trajectory of tip vortex core and the form of tip vortex cavitation（TVC） in different cavitation situations. Laser Doppler velocimetry（LDV） was employed to measure the tip vortex flow field in some typical sections along the vortex trajectory with the case of cavitation free. Stereo particle image velocimetry（SPIV） system was used to measure the velocity and vorticity distributions with and without cavitation. Series measurement results such as velocity and vorticity distributions, the trajectory of tip vortex core, the vortex core radius, cavity size and cavitation inception number were obtained. The results demonstrated that the minimum pressure coefficient in the vortex core obtained by flow field measurement was quite coincident with the tip vortex cavitation inception number obtained under the condition of high incoming velocity and low air content. And TVC would decrease the vortex strength comparing with the case without cavitation.展开更多
The tip-leakage vortex(TLV)cavitation is a challenging issue for a variety of axial hydraulic turbines and pumps from both technical and scientific viewpoints.The flow characteristics of the TLV cavitation were widely...The tip-leakage vortex(TLV)cavitation is a challenging issue for a variety of axial hydraulic turbines and pumps from both technical and scientific viewpoints.The flow characteristics of the TLV cavitation were widely studied in the past decades,but the knowledge about the tip-leakage cavitating flow is still limited.The 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 cavitation.It 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 cavitation.It is also suggested that the development of the TLV cavitation will significantly influence the distributions of the vorticity and the turbulence kinetic energy.Due to the complexity of the TLV cavitation,it is still an open question how to suppress the TLV cavitation in a simple but effective way.Finally,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.展开更多
A series of blade tip geometries, including original plain tip, rounded tip on the pressure side and diverging tip towards the suction side, were adopted to investigate the effect of blade geometry on tip leakage vort...A series of blade tip geometries, including original plain tip, rounded tip on the pressure side and diverging tip towards the suction side, were adopted to investigate the effect of blade geometry on tip leakage vortex dynamics and cavitation pattern in an axial-flow pump. On the basis of the computation, it clearly shows the flow structure in the clearance for different tip configurations by the detailed data of axial velocity and turbulent kinetic energy. The in-plain trajectory, in aspects of the angle between the blade suction side and vortex core and the initial point of tip leakage vortex, was presented using the maximum swirling strength method. The most striking feature is that the inception location of tip leakage vortex is delayed for chamfered tip due to the change of blade loading on suction side. Some significant non-dimensional parameters, such as pressure, swirling strength and turbulent kinetic energy, were used to depict the characteristics of tip vortex core. By the distribution of circumferential vorticity which dominates the vortical flows near the tip region, it is observed that the endwall detachment as the leakage flow meets the mainstream varies considerably for tested cases. The present study also indicates that the shear layer feeds the turbulence into tip leakage vortex core, but the way is different. For the chamfered tip, high turbulence level in vortex core is mainly from the tip clearance where large turbulent kinetic energy emerges, while it is almost from a layer extending from the suction side corner for rounded tip. At last, the visualized observations show that tip clearance cavitation is eliminated dramatically for rounded tip but more intensive for chamfered tip, which can be associated with the vortex structure in the clearance.展开更多
The unsteady turbulent cloud cavitation around a NACA66 hydrofoil was simulated using the filter-based density corrected model(FBDCM). The cloud cavitation was treated as a homogeneous liquid-vapor mixture and the eff...The unsteady turbulent cloud cavitation around a NACA66 hydrofoil was simulated using the filter-based density corrected model(FBDCM). The cloud cavitation was treated as a homogeneous liquid-vapor mixture and the effects of turbulent eddy viscosity were reduced in cavitation regions near the hydrofoil and in the wake. The numerical results(in terms of the vapor shedding structure and transient pressure pulsation due to cavitation evolution) agree well with the available experimental data, showing the validity of the FBDCM method. Furthermore, the interaction of vortex and cavitation was analyzed based on the vorticity transport equation, revealing that the cavitation evolution has a strong connection with vortex dynamics. A detailed analysis shows that the cavitation could promote the vortex production and flow unsteadiness by the dilatation and baroclinic torque terms in the vorticity transport equation.展开更多
Propeller is an important equipment of ocean structures.It has characteristics of complex geometry and periodic vortex shed,which means high research value.This paper takes DTMB419 propeller as the research object.A d...Propeller is an important equipment of ocean structures.It has characteristics of complex geometry and periodic vortex shed,which means high research value.This paper takes DTMB419 propeller as the research object.A detailed study is conducted on the wake vortices in non-cavitation state and cavitation state.Three vortex identification methods are used to compare the vortices capture effects from downstream sections and three-dimensional perspectives.The results show that,the third-generation vortex identification technologyΩ_(R)shows obvious advantages.At the same time,FW-H equation is used to predict propeller noise,and the relationship between nonlinear sound source distribution and vortices distribution is analyzed.It is found that the distribution of Lighthill tensor is consistent withΩ_(R),which proves the advantages and potential of third-generation vortex identification technology from acoustic perspective.展开更多
This study presents results of experiments where roughness applications are evaluated in delaying the tip vortex cavitation inception of an elliptical foil.High-speed video recordings and laser doppler velocimetry(LDV...This study presents results of experiments where roughness applications are evaluated in delaying the tip vortex cavitation inception of an elliptical foil.High-speed video recordings and laser doppler velocimetry(LDV)measurements are employed to provide further details on the cavitation behavior and tip vortex flow properties in different roughness pattern configurations.The angular momentum measurements of the vortex core region at one chord length downstream of the tip indicate that roughness leads to a lower angular momentum compared with the smooth foil condition while the vortex core radius remains similar in the smooth and roughened conditions.The observations show that the cavitation number for tip vortex cavitation inception is reduced by 33%in the optimized roughness pattern compared with the smooth foil condition where the drag force increase is observed to be around 2%.During the tests,no obvious differences in the cavitation inception properties of uniform and non-uniform roughness distributions are observed.However,the drag force is found to be higher with a non-uniform roughness distribution.展开更多
Viewed as sinews and muscles of fluid motion,coherent vortical structures with their interactions are key to understanding the flow dynamics.Based upon this observation,we explore the possibility of efficient flow con...Viewed as sinews and muscles of fluid motion,coherent vortical structures with their interactions are key to understanding the flow dynamics.Based upon this observation,we explore the possibility of efficient flow control by directly manipulating vortices numerically inside the flow field based on the vortex definition and identification system of Liutex.The objective is twofold:(1)to study the vortex dynamics,for example,by observing the response of the flow to strengthening or weakening of certain vortices,and(2)to obtain efficient vortex-based control strategies which might lead us to practical applications.In the present numerical study,the manipulating of vortices is achieved by introducing additional source(force)terms to the Navier-Stokes equations,which hereafter will be collectively called Liutex force field model.Methodologies including controlling the rotation strength and centripetal force of particular vortices are detailed in a flow past a cylinder with different control purposes at Reynolds number of 200.Further examples are provided with a cavitating flow around two-dimensional Clark-Y hydrofoil,with particular interests on cavitation suppression.It is illustrated particular vortex with cavitation encircled could be effectively suppressed.展开更多
Cavitation is a widespread and detrimental phenomenon in hydraulic machinery, therefore, it requires to be accurately predicted. In this study, large eddy simulation (LES), scale-adaptive simulation (SAS) and grid-ada...Cavitation is a widespread and detrimental phenomenon in hydraulic machinery, therefore, it requires to be accurately predicted. In this study, large eddy simulation (LES), scale-adaptive simulation (SAS) and grid-adaptive simulation (GAS) are employed to investigate the unsteady cavitating flow around a NACA0009 hydrofoil. The prediction accuracy of GAS, SAS, both using the shear-stress transport (SST) k — ω model as baseline turbulence model, is validated by comparing with experimental and LES results. The cavity behaviors and turbulence fields are analyzed systematically. Results show that the GAS gives a more reasonable turbulent viscosity and accurately predicts the periodic evolution of typical vortical structures of cavitating flow, such as tip leakage vortex cavitation, tip separation vortex cavitation, leading-edge cavitation, and trailing-edge vortex. The time-averaged cavity volume, volume fluctuation amplitude, and characteristic frequencies of cavities predicted by the GAS are very closed to the LES, while the SAS fails to accurately capture these cavity characteristics. Furthermore, the local trace criterion is applied to extract the vortical structures and to analyze the swirling patterns of the tip leakage vortex. Multi-scale vortical structures in LES are well identified by local trace criterion. The prediction accuracy of the SAS method for small-scale vortical structures, such as the vortex shedding on the suction side and the vortex rope around the tip leakage vortex, is obviously insufficient, while the GAS has a higher accuracy in predicting vortex shedding. The tip leakage vortex and induced vortex extracted from GAS are also closer to that of LES in both swirling patterns and scale.展开更多
Tip vortex cavitation(TVC)is an important cavitation phenomenon in marine propeller.The formation and evolution of tip vortex cavitation are hot topics consistently both in engineering application and mechanism resear...Tip vortex cavitation(TVC)is an important cavitation phenomenon in marine propeller.The formation and evolution of tip vortex cavitation are hot topics consistently both in engineering application and mechanism research.In this paper some recent studies on tip vortex cavitation inception and the noise of tip vortex cavitation evolution are presented.The effects of both flow field and water qualities on tip vortex cavitation inception are considered by experiments and numerical simulations.The results show that besides the average minimum pressure in the vortex core the turbulence fluctuation and water qualities including air content and nuclei distribution have great influence on tip vortex cavitation inception.Based on the idea of first nucleus cavitating in tip vortex core new prediction formula for tip vortex cavitation inception is proposed.The synchronous technique of high speed video observation and noise measurement are adopted to study the development of tip vortex cavitation.S-type total noise characteristics are obtained when cavitation number from low to high.Vortex singing is found in the case where the tip vortex cavitation just before leaves the tip region.The excited mechanism of vortex singing is proposed by analyzing the wave propagation on the interface of vortex cavity.展开更多
In the present paper, the Vortex Identified Zwart-Gerber-Belamri（VIZGB） cavitation model coupled with the SST-CC turbulence model is used to investigate the unsteady tip-leakage cavitating flow induced by a NACA0009...In the present paper, the Vortex Identified Zwart-Gerber-Belamri（VIZGB） cavitation model coupled with the SST-CC turbulence model is used to investigate the unsteady tip-leakage cavitating flow induced by a NACA0009 hydrofoil. A qualitative comparison between the numerical and experimental results is made. In order to quantitatively evaluate the reliability of the numerical data, the verification and validation（V＆V） procedures are used in the present paper. Errors of numerical results are estimated with seven error estimators based on the Richardson extrapolation method. It is shown that though a strict validation cannot be achieved, a reasonable prediction of the gross characteristics of the tip-leakage cavitating flow can be obtained. Based on the numerical results, the influence of the cavitation on the tip-leakage vortex（TLV） is discussed, which indicates that the cavitation accelerates the fusion of the TLV and the tip-separation vortex（TSV）. Moreover, the trajectory of the TLV, when the cavitation occurs, is close to the side wall.展开更多
基金Supported by the National Natural Science Foundation of China （50576088, 20706049） and Zhejiang Provincial Key Science Foundation （2006C21064, 2007C21067）.
文摘The design method of small-flow high-head centrifugal-vortex pump was presented. This pump, configured with inducer, complex-centrifugal impeller and open-vortex impeller, was put forward to deliver gas-liquid two-phase mixture. An HTB-5/60 type sample pump was developed and tested on a closed-loop test rig. Experimental studies on performance and cavitation tests for gas-liquid two-phase mixture were carried out compared with pure-water experimental results. Also the effect of gas phase on pump was analyzed and discussed. The experimental results show that performance and cavitation characteristics of the sample purnp deteriorates progressively with increasing volume fraction of gas. When the total capacity Qm is between 4.5 m^3·h^-1 and 6 m^3·h^-1 and the gas flow rate qg below 0.66 m^3·h^-1, or qg/Qm is lower than 15%, the characteristic curves are approximately parallel to those in pure water test, but the performance deteriorates sharply until an abrupt flow-cutting at a critical volume fraction of gas. This pump is found suitable for transporting gas-liquid two-phase mixture when working around rated capacity of 5 m^3·h^-1 with qglQm below 15%.
基金Project supported by the Key Project of National Natural Science Foundation of China(Grant No.11332009)
文摘In this paper, recent measurements of tip vortex flow with and without cavitation carried out in Cavitation Mechanism Tunnel of China Ship Scientific Research Center（CSSRC） are presented. The elliptic hydrofoil with section NACA 662-415 was adopted as test model. High-speed video（HSV） camera was used to visualize the trajectory of tip vortex core and the form of tip vortex cavitation（TVC） in different cavitation situations. Laser Doppler velocimetry（LDV） was employed to measure the tip vortex flow field in some typical sections along the vortex trajectory with the case of cavitation free. Stereo particle image velocimetry（SPIV） system was used to measure the velocity and vorticity distributions with and without cavitation. Series measurement results such as velocity and vorticity distributions, the trajectory of tip vortex core, the vortex core radius, cavity size and cavitation inception number were obtained. The results demonstrated that the minimum pressure coefficient in the vortex core obtained by flow field measurement was quite coincident with the tip vortex cavitation inception number obtained under the condition of high incoming velocity and low air content. And TVC would decrease the vortex strength comparing with the case without cavitation.
基金the National Natural Science Foundation of China(Grant Nos.51822903,1772239)the China Postdoctoral Science Foundation(Grant No.2020M682471).
文摘The tip-leakage vortex(TLV)cavitation is a challenging issue for a variety of axial hydraulic turbines and pumps from both technical and scientific viewpoints.The flow characteristics of the TLV cavitation were widely studied in the past decades,but the knowledge about the tip-leakage cavitating flow is still limited.The 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 cavitation.It 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 cavitation.It is also suggested that the development of the TLV cavitation will significantly influence the distributions of the vorticity and the turbulence kinetic energy.Due to the complexity of the TLV cavitation,it is still an open question how to suppress the TLV cavitation in a simple but effective way.Finally,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.
基金the National Natural Science Foundation of China(Grant No.51479083)prospective Joint Research Proj ectofJiangsu Province(Grant No.BY2015064-08)+1 种基金Primary Research&Development Plan of Jiangsu Province(Grant Nos.BE2015001-3 and BE2015146)333Project of Jiangsu Province and Six Talent Peaks Project in Jiangsu Province(Grant No.HYGC-008)
文摘A series of blade tip geometries, including original plain tip, rounded tip on the pressure side and diverging tip towards the suction side, were adopted to investigate the effect of blade geometry on tip leakage vortex dynamics and cavitation pattern in an axial-flow pump. On the basis of the computation, it clearly shows the flow structure in the clearance for different tip configurations by the detailed data of axial velocity and turbulent kinetic energy. The in-plain trajectory, in aspects of the angle between the blade suction side and vortex core and the initial point of tip leakage vortex, was presented using the maximum swirling strength method. The most striking feature is that the inception location of tip leakage vortex is delayed for chamfered tip due to the change of blade loading on suction side. Some significant non-dimensional parameters, such as pressure, swirling strength and turbulent kinetic energy, were used to depict the characteristics of tip vortex core. By the distribution of circumferential vorticity which dominates the vortical flows near the tip region, it is observed that the endwall detachment as the leakage flow meets the mainstream varies considerably for tested cases. The present study also indicates that the shear layer feeds the turbulence into tip leakage vortex core, but the way is different. For the chamfered tip, high turbulence level in vortex core is mainly from the tip clearance where large turbulent kinetic energy emerges, while it is almost from a layer extending from the suction side corner for rounded tip. At last, the visualized observations show that tip clearance cavitation is eliminated dramatically for rounded tip but more intensive for chamfered tip, which can be associated with the vortex structure in the clearance.
基金supported by the National Natural Science Foundation of China(Grant Nos.51206087,51306018,51179091 and 51376100)the National Basic Research Program of China("973"Project)(Grant No.2011BAF03B01)the Open Research Fund Program of State key Laboratory of Hydroscience and Engineering(Grant No.2014-KY-05 and 2015-E-03)
文摘The unsteady turbulent cloud cavitation around a NACA66 hydrofoil was simulated using the filter-based density corrected model(FBDCM). The cloud cavitation was treated as a homogeneous liquid-vapor mixture and the effects of turbulent eddy viscosity were reduced in cavitation regions near the hydrofoil and in the wake. The numerical results(in terms of the vapor shedding structure and transient pressure pulsation due to cavitation evolution) agree well with the available experimental data, showing the validity of the FBDCM method. Furthermore, the interaction of vortex and cavitation was analyzed based on the vorticity transport equation, revealing that the cavitation evolution has a strong connection with vortex dynamics. A detailed analysis shows that the cavitation could promote the vortex production and flow unsteadiness by the dilatation and baroclinic torque terms in the vorticity transport equation.
基金the National Key Researchand Development Program of China(Grant No.2019YFB1704200)the National Natural Science Foundation of China(Grant Nos.51909160,52131102 and 51879159).
文摘Propeller is an important equipment of ocean structures.It has characteristics of complex geometry and periodic vortex shed,which means high research value.This paper takes DTMB419 propeller as the research object.A detailed study is conducted on the wake vortices in non-cavitation state and cavitation state.Three vortex identification methods are used to compare the vortices capture effects from downstream sections and three-dimensional perspectives.The results show that,the third-generation vortex identification technologyΩ_(R)shows obvious advantages.At the same time,FW-H equation is used to predict propeller noise,and the relationship between nonlinear sound source distribution and vortices distribution is analyzed.It is found that the distribution of Lighthill tensor is consistent withΩ_(R),which proves the advantages and potential of third-generation vortex identification technology from acoustic perspective.
基金This work was supported by the VINNOVA through the RoughProp project(Grant No.2018-04085).The experimental measurements are conducted in the free surface cavitation tunnel at the Kongsberg Hydrodynamic Research Center,Kristinehamn,Sweden.
文摘This study presents results of experiments where roughness applications are evaluated in delaying the tip vortex cavitation inception of an elliptical foil.High-speed video recordings and laser doppler velocimetry(LDV)measurements are employed to provide further details on the cavitation behavior and tip vortex flow properties in different roughness pattern configurations.The angular momentum measurements of the vortex core region at one chord length downstream of the tip indicate that roughness leads to a lower angular momentum compared with the smooth foil condition while the vortex core radius remains similar in the smooth and roughened conditions.The observations show that the cavitation number for tip vortex cavitation inception is reduced by 33%in the optimized roughness pattern compared with the smooth foil condition where the drag force increase is observed to be around 2%.During the tests,no obvious differences in the cavitation inception properties of uniform and non-uniform roughness distributions are observed.However,the drag force is found to be higher with a non-uniform roughness distribution.
基金supported by the National Nature Science Foundation of China(Grant Nos.11702159,51879159 and 51909160).
文摘Viewed as sinews and muscles of fluid motion,coherent vortical structures with their interactions are key to understanding the flow dynamics.Based upon this observation,we explore the possibility of efficient flow control by directly manipulating vortices numerically inside the flow field based on the vortex definition and identification system of Liutex.The objective is twofold:(1)to study the vortex dynamics,for example,by observing the response of the flow to strengthening or weakening of certain vortices,and(2)to obtain efficient vortex-based control strategies which might lead us to practical applications.In the present numerical study,the manipulating of vortices is achieved by introducing additional source(force)terms to the Navier-Stokes equations,which hereafter will be collectively called Liutex force field model.Methodologies including controlling the rotation strength and centripetal force of particular vortices are detailed in a flow past a cylinder with different control purposes at Reynolds number of 200.Further examples are provided with a cavitating flow around two-dimensional Clark-Y hydrofoil,with particular interests on cavitation suppression.It is illustrated particular vortex with cavitation encircled could be effectively suppressed.
基金supported by the National Natural Science Foundation of China(Grant No.51976006,52106039)This work was supported by the National Science and Technology Major Project(Grant No.2017-II-003-0015)+1 种基金the Aeronautical Science Foundation of China(Grant No.2018ZB51013)the Fundamental Research Funds for the Central Universities.
文摘Cavitation is a widespread and detrimental phenomenon in hydraulic machinery, therefore, it requires to be accurately predicted. In this study, large eddy simulation (LES), scale-adaptive simulation (SAS) and grid-adaptive simulation (GAS) are employed to investigate the unsteady cavitating flow around a NACA0009 hydrofoil. The prediction accuracy of GAS, SAS, both using the shear-stress transport (SST) k — ω model as baseline turbulence model, is validated by comparing with experimental and LES results. The cavity behaviors and turbulence fields are analyzed systematically. Results show that the GAS gives a more reasonable turbulent viscosity and accurately predicts the periodic evolution of typical vortical structures of cavitating flow, such as tip leakage vortex cavitation, tip separation vortex cavitation, leading-edge cavitation, and trailing-edge vortex. The time-averaged cavity volume, volume fluctuation amplitude, and characteristic frequencies of cavities predicted by the GAS are very closed to the LES, while the SAS fails to accurately capture these cavity characteristics. Furthermore, the local trace criterion is applied to extract the vortical structures and to analyze the swirling patterns of the tip leakage vortex. Multi-scale vortical structures in LES are well identified by local trace criterion. The prediction accuracy of the SAS method for small-scale vortical structures, such as the vortex shedding on the suction side and the vortex rope around the tip leakage vortex, is obviously insufficient, while the GAS has a higher accuracy in predicting vortex shedding. The tip leakage vortex and induced vortex extracted from GAS are also closer to that of LES in both swirling patterns and scale.
基金Project supported by National Natural Science Foundation of China(Grant Nos.11772305,11332009).
文摘Tip vortex cavitation(TVC)is an important cavitation phenomenon in marine propeller.The formation and evolution of tip vortex cavitation are hot topics consistently both in engineering application and mechanism research.In this paper some recent studies on tip vortex cavitation inception and the noise of tip vortex cavitation evolution are presented.The effects of both flow field and water qualities on tip vortex cavitation inception are considered by experiments and numerical simulations.The results show that besides the average minimum pressure in the vortex core the turbulence fluctuation and water qualities including air content and nuclei distribution have great influence on tip vortex cavitation inception.Based on the idea of first nucleus cavitating in tip vortex core new prediction formula for tip vortex cavitation inception is proposed.The synchronous technique of high speed video observation and noise measurement are adopted to study the development of tip vortex cavitation.S-type total noise characteristics are obtained when cavitation number from low to high.Vortex singing is found in the case where the tip vortex cavitation just before leaves the tip region.The excited mechanism of vortex singing is proposed by analyzing the wave propagation on the interface of vortex cavity.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51576143,11772239 and 91752105)the Science and Technology on Water Jet Propulsion Laboratory(Grant No.61422230101162223002)
文摘In the present paper, the Vortex Identified Zwart-Gerber-Belamri（VIZGB） cavitation model coupled with the SST-CC turbulence model is used to investigate the unsteady tip-leakage cavitating flow induced by a NACA0009 hydrofoil. A qualitative comparison between the numerical and experimental results is made. In order to quantitatively evaluate the reliability of the numerical data, the verification and validation（V＆V） procedures are used in the present paper. Errors of numerical results are estimated with seven error estimators based on the Richardson extrapolation method. It is shown that though a strict validation cannot be achieved, a reasonable prediction of the gross characteristics of the tip-leakage cavitating flow can be obtained. Based on the numerical results, the influence of the cavitation on the tip-leakage vortex（TLV） is discussed, which indicates that the cavitation accelerates the fusion of the TLV and the tip-separation vortex（TSV）. Moreover, the trajectory of the TLV, when the cavitation occurs, is close to the side wall.
