摘要
用体三维速度测量技术（volumetric three-component velocimetry measurements,V3V）实验研究了涡轮桨搅拌槽内桨叶附近流场。通过速度数据得到三维流场特性,确定尾涡三维结构;分析了叶片后方30°截面轴向、径向和环向速度沿径向分布规律;对比了V3V和2D-PIV（particle image velocimetry）径向和轴向速度,发现速度分布吻合较好,特别是尾涡所在的射流区。用2D-PIV方法对尾涡发展规律进行研究,发现受流体自由液面影响,尾涡轨迹向上倾斜,并与水平方向成10°,上、下尾涡运动轨迹不对称,下尾涡运动比上尾涡稍快,衰减亦较快,这与V3V实验结果一致;叶片后方60°尾涡依然清晰可见。用V3V和2D-PIV方法对桨叶附近湍流各向同性假设进行了分析,发现桨叶区和尾涡所在位置湍动能被各向同性假设近似法高估了25%～33%,桨叶区和尾涡所在位置趋向于各向异性。
The flow field nearby standard Rushton impeller in a stirred vessel was investigated by volumetric three-component velocimetry（V3V） measurements, which about 18000 vectors were captured in a cubic volume of approximately 140 mm in height by 140 mm in width by 100 mm in depth. The characteristics of three-dimensional flow field and the structure of trailing vortices were derived from velocity data. The distributions of radial, axial and tangential velocities in 30° cross-section behind the impeller were analyzed and the distributions of radial and axial velocities by V3 V were in good agreement with these by 2D-PIV（particle image velocimetry）, especially for trailing vortices in the region of discharge streams. The 2D-PIV study on development of trailing vortices shows that the trailing vortices had an upward inclination at an angle of 10° to the horizontal line as a result of influence by the liquid free surface. The traces of movement were asymmetrical between upper and lower trailing vortices in a way that the movement and decay of the lower vortex were slightly faster than the upper one, which is consistent with the V3 V results. Further, trailing vortices were still visible at 60° angle behind the impeller blade. Compared results of both V3 V and 2D-PIV to that of pseudo-isotropic approximation, the normalized turbulent kinetic energy（k/Vtip） by pseudo-isotropic approximation was overestimated 25%—33% at locations of trailing vortices and the impeller, where turbulence tends to be anisotropic.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2016年第11期4580-4586,共7页
CIESC Journal
关键词
V3V
PIV
尾涡
涡轮桨
流场
各向同性
V3V
PIV
trailing vortex
Rushton impeller
flow field
isotropy
