基于PIV速度场测量的压强梯度计算

PIV velocity field measurement-based pressure gradient computation

介绍了基于PIV速度场测量结果计算压强梯度的基本原理和3种不同的计算方法,并通过对流高斯涡模型系统研究了离散格式选取、PIV参数设置和流场特征等对压强梯度计算的影响.结果表明:PIV速度测量的精度是压强梯度计算的关键性影响因素,1%噪声对结果的影响比其他过程高约2个数量级;时间分辨率和空间分辨率的设置并非越高越好,而是有个合适的中间值;拉格朗日方法在大多数情况下优于欧拉方法,但当流动结构较复杂时性能较差,应根据流动类型和流场特征合理选取压强梯度计算方法.

A description of the basic operation principles of the （particle image velocimetry） PIV velocity field measurement-based pressure gradient calculations and three different methods were described in detail.Then,an analytic test case of the convection of a Gaussian vortex was considered to give insight into the influences of the discrete scheme,parameter setting and flow field characteristic on successful determination of the pressure gradient field.Results showed that the uncertainty of pressure gradient calculation was dominated by errors of PIV velocity measurements.The effect of 1% errors in velocity on the result was about two orders of magnitude higher than any other steps.Time and spatial resolution settings were not as high as possible,but there was a suitable intermediate value.The Lagrangian approach was superior to the Euler approach in most cases,but the former became worse when the flow structure was more complex,the pressure gradient calculation method should be selected according to the flow type and flow field characteristics.