低速旋转盘腔内液体流动特性

Study on Flow Characteristics of the Fluid in Low Speed Rotating Cavity

利用粒子图像测速测试平台研究了低速旋转盘腔轴向中截面的液体流动特性,并利用Realizable k-ε模型对低速旋转盘腔内液体流场进行三维数值模拟,模拟结果与实验值吻合较好,最大相对误差为16.9%.利用模型方程研究了导流板数、导流板相对长度、进口雷诺数和旋转雷诺数对盘腔内液体流动的影响.结果表明,盘腔体积平均相对速度及涡量受进口雷诺数(Re)、导流板数、导流板相对长度影响较大,当进口Re从17000升至53000时,体积平均相对速度及涡量分别增加2.4倍和1.6倍;当导流板数由0提高至4时,体积平均相对速度及涡量增幅分别为62%和30%;当导流板相对长度由0.5提高至0.93时,体积平均相对速度及涡量增幅分别为114%和58%.盘腔压损主要受进口Re的影响,当进口Re从17000升至53000时,盘腔压损增长8倍,而导流板数及导流板相对长度对压损的影响较小,增幅均小于5%.为强化旋转盘腔内流体与壁面间传热,减小流体阻力,应优化进口Re、尽量增加导流板数和长度.

A particle image velocimetry （PIV） test setup was used to study the fluid flow characteristics of axial center cross-section in a low speed rotating cavity, and three-dimensional numerical simulation of flow field in low-speed rotating cavity was performed based on the Realizable k-ε model. The results of simulation were consistent with those from experimental study with a maximum relative error less than 16.9%, indicating the validity of the simulation methods and model. Besides, the effects of number and length of deflector, Reynolds number 0 of cavity inlet and rotating Reynolds number on fluid flow in the rotating cavity were examined based on the model equation. The results show that Re of cavity inlet, number and relative length of deflector have obvious impact on volume-averaged relative velocity and vorticity in the cavity, when Re of cavity inlet varies from 17 000 to 53 000, volume-averaged relative velocity and vorticity increases 2.4 times and 1.6 times, respectively. When the number of deflector varies from 0 to 4, the growth rate of that is 62% and 30% respectively. When the relative length of deflector increases from 0.5 to 0.93, volume-averaged relative velocity and vorticity increases 114% and 58% respectively. Pressure loss in the cavity is affected mainly by Re of cavity inlet, when Re of cavity inlet varies from 17 000 to 53 000, pressure loss in the cavity increases 8 times, while with the increase of number and relative length of deflector, pressure loss increases less than 5%. Under the present investigation conditions, in order to improve fluid disturbance in the cavity and reduce fluid flow resistance, it would be better to select an appropriate inlet velocity of the cavity, install deflectors and increase its relative length.