The effect of streamwise vortices generated from passive vortex generators was investigated to manipulate the separation bubble behind the vertical fence. The experiments were carried out in a circulating water channe...The effect of streamwise vortices generated from passive vortex generators was investigated to manipulate the separation bubble behind the vertical fence. The experiments were carried out in a circulating water channel and the velocity fields were measured using 2D and stereoscopic PIV method.The distance between the vortex generator and fence and the effect of the Reynolds number were investigated. In addition,the effect of boundary layer thickness was also investigated. The averaged recirculation lengths were compared with that of uncontrolled fence flow. The results showed the oscillatory variation of recirculation region appeared under the existence of vortex generators. The reduction of the separation bubble became larger when the fence was submerged in the thick boundary layer with increasing the distance between the generator and fence. When the boundary layer is thin,vortex generator can only suppress the separation bubble under the specific condition.展开更多
Particle Image Velocimetry (PIV) technology was used to study the unsteady internal flow in a double-blade centrifugal pump (DBCP) impeller at the design flow rate.Relative velocity distributions and turbulence intens...Particle Image Velocimetry (PIV) technology was used to study the unsteady internal flow in a double-blade centrifugal pump (DBCP) impeller at the design flow rate.Relative velocity distributions and turbulence intensity distributions in the DBCP impeller at six phase conditions were obtained.And mean dimensionless relative velocity,turbulence intensity,mean absolute flow angle,mean relative flow angle,mean dynamic pressure and mean angular momentum distributions at the different radii of impeller were calculated.Results show that from impeller inlet to impeller outlet,turbulence intensities gradually decrease.With the increase of radius r,mean dimensionless relative velocity first decreases and then increases,while variation tendencies of mean absolute flow angle and mean dynamic pressure are the opposite.With the increase of radius r,turbulence intensity and mean relative flow angle first decrease,then increase,and then decrease,while mean angular momentum gradually increases.展开更多
基金supported from the Priority Research Centers Program(2012-048078)Basic Science Research Program(2012-008918)+1 种基金through the National Research Foundation(NRF)a grant(08GASPLANTC04) from the program of KAIA funded by the Ministry of Land,Infrastructure and Transport of the Republic of Korea
文摘The effect of streamwise vortices generated from passive vortex generators was investigated to manipulate the separation bubble behind the vertical fence. The experiments were carried out in a circulating water channel and the velocity fields were measured using 2D and stereoscopic PIV method.The distance between the vortex generator and fence and the effect of the Reynolds number were investigated. In addition,the effect of boundary layer thickness was also investigated. The averaged recirculation lengths were compared with that of uncontrolled fence flow. The results showed the oscillatory variation of recirculation region appeared under the existence of vortex generators. The reduction of the separation bubble became larger when the fence was submerged in the thick boundary layer with increasing the distance between the generator and fence. When the boundary layer is thin,vortex generator can only suppress the separation bubble under the specific condition.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51079062,51179075,51109095,51239005,and51209105)the National Science & Technology Pillar Program of China(Grant Nos. 2011BAF14B03 and 2013BAK06B02)+3 种基金the Natural ScienceFund of Jiangsu Province of China (Grant No. BY2011140)Science and Technology Support Program of Jiangsu Province of China (Grant Nos.BE2012129 and BE2012131)the Priority Academic Program Development of Jiangsu Higher Education Institutions and Senior Professional Scientific Research Project of Jiangsu University of China (Grant No.12JDG045)supported from the Priority Research Centers Program (2012-048078) through the National Research Foundation of the Republic of Korea
文摘Particle Image Velocimetry (PIV) technology was used to study the unsteady internal flow in a double-blade centrifugal pump (DBCP) impeller at the design flow rate.Relative velocity distributions and turbulence intensity distributions in the DBCP impeller at six phase conditions were obtained.And mean dimensionless relative velocity,turbulence intensity,mean absolute flow angle,mean relative flow angle,mean dynamic pressure and mean angular momentum distributions at the different radii of impeller were calculated.Results show that from impeller inlet to impeller outlet,turbulence intensities gradually decrease.With the increase of radius r,mean dimensionless relative velocity first decreases and then increases,while variation tendencies of mean absolute flow angle and mean dynamic pressure are the opposite.With the increase of radius r,turbulence intensity and mean relative flow angle first decrease,then increase,and then decrease,while mean angular momentum gradually increases.
