基于简易PIV的圆柱绕流压力场重构

Measurement of Transient Pressure Field Based on Simple Particle Image Velocimetry

采用简易粒子成像测速仪(PIV)装置测量入口流速为14.3cm/s时圆柱绕流的速度场,运用有限容积法和直接积分法重构压力场。对比Fluent模拟速度场结果,分析简易PIV的速度场测量误差;对比Fluent模拟压力场结果,分析基于Fluent模拟速度场以及PIV实测速度场的不同算法重构压力场误差。结果表明:在简易PIV系统中,摄像机采用适合的空间分辨率与时间分辨率能有效减小速度场测量误差。基于Fluent模拟速度场数据,当给定第一边界条件时,有限容积法的压力场重构误差小于直接积分法,均方根误差分别为1.73%,8.99%;基于PIV实测速度场,有限容积法的压力场重构误差大于直接积分法,均方根误差分别为26.58%,12.72%;降低速度场误差与获取准确的边界条件均能有效提高压力场重构精度。通过采用低成本的PIV装置,探究获取流体的瞬态压力场重构方法,降低了PIV中重构压力场的成本。

A simple PIV device is adopted to measure the velocity field of flow around a cylinder when the inlet velocity is 14.3 cm/s, and the pressure field is reconstructed by finite volume method and direct integral method. The error of velocity field measurement by simple PIV is analyzed by referring to the results of Fluent simulation, and the error of pressure field reconstruction by different algorithms based on Fluent-simulated velocity field and PIV-measured velocity field is also analyzed by comparing to the result of Fluent simulation. Results demonstrated that in the simple PIV system, camera could reduce the error of velocity field measurement by adopting suitable spatial resolution and time resolution. When given the first boundary condition on the basis of Fluent-simulated data, the error of pressure field reconstruction by finite volume method is smaller than that by direct integral method, with the root mean square error reaching 1.73% and 8.99%, respectively;on the basis of PIV-measured data, the reconstruction error by finite volume method is greater than that by direct integral method, with the root mean square error amounting to 26.58% and 12.72%, respectively. In conclusion, reducing the error of velocity field and setting up accurate boundary conditions could improve the reconstruction accuracy of pressure field. The analysis result is aimed at exploring the reconstruction method for transient pressure field of fluid through low-cost PIV device, so as to reduce the cost of measuring pressure field from PIV.