基于PIV试验的水介质液力偶合器涡轮流场仿真评价

Evaluation of Flow Field Simulation of Turbine in Water-Medium Hydrodynamic Coupling Based on PIV Experiment

为揭示水介质液力偶合器涡轮流场的特征及演化规律,基于计算流体动力学(CFD)技术,采用4种湍流模型(DES、DDES、IDDES、LES)仿真制动和牵引工况下的涡轮流场结构.通过粒子图像测速(PIV)试验,采用静态、动态图像标定方法实测涡轮流场图像.通过PIV流场试验结果与CFD仿真结果的对比评价4种湍流模型的适用性.结果表明:制动工况下,LES模型对主流区域多尺度漩涡流场结构的仿真结果趋于真实,流速为3. 52～3. 81 m/s,涡量为480～540 s-1; IDDES模型对叶片近壁面区域流速场的仿真表现卓越,流速为3. 14～3. 51 m/s,而DES模型对该区域内涡量场的仿真较好,涡量为500～570 s-1.牵引工况下,DDES和IDDES模型的仿真结果失真; DES模型对主流区域漩涡流场结构的仿真效果不如LES模型,但是能够体现多尺度涡旋沿圆周方向运动的基本趋势; LES模型的仿真结果与PIV试验结果吻合,能够体现沿圆周方向运动的多尺度涡旋之间的相互混合作用,流速为1. 40～3. 60 m/s,涡量为30～130 s-1.研究结果可为精确仿真液力偶合器涡轮流场提供一定的技术指导.

In order to reveal the characteristics and evolution law of multi-scale vortex flow field in water medium hydrodynamic coupling based on the CFD technique,four kinds of turbulence models(DES,DDES,IDDES,LES)were used to simulate the internal multi-scale vortex flow field of turbine in hydrodynamic coupling in braking and traction conditions.The flow images of internal flow field in turbine were collected by particle image velocimetry(PIV)technology,static and dynamic image calibration methods were used to calculate the flow field under different conditions.The applicability of the four turbulence models was evaluated on the basis of the comparison of PIV experimental results.The results show that under the braking condition,the simulation results of multi-scale vortex flow field in mainstream region used by LES turbulence model tend to be true,the flow velocity range is from 3.52 to 3.81 m/s,and the vorticity range is from 480 to 540 s^-1.While the simulation results of multi-scale vortex flow field in the near-wall region of the blade used by IDDES turbulence model are outstanding in performance,the flow velocity range is from 3.14 to 3.51 m/s,in this area,simulation results of vortex field used by DES turbulence model are better than those of LES turbulence model,and the vorticity range is from 500 to 570 s^-1.As far as traction condition is concerned,the simulation results are distorted when DDES turbulence model and IDDES turbulence model are used,and the simulation results of multi-scale vortices in mainstream region used by DES turbulence model are not as good as those of LES turbulence model,but it can reflect the basic movement trend of multi-scale vortices along the circumferential direction.The simulation results used by LES turbulence model are in good agreement with the PIV experimental results,it is possible to embody the mutual mixing process of these multi-scale vortices moving along the circumferential direction,the flow velocity range is from 1.40 to 3.60 m/s,and the vorticity range is from 30 to 130 s^-1.It will provide some technical guidance for the precise simulation of hydrodynamic coupling.