二维数字滤波在物理模型流场测量系统中的应用

粒子跟踪测速(PTV)是一种非接触式的流场测量技术,它可以实时的获得二维流速平面的速度数据。PTV系统通过数字相机拍摄布撒在流场中的示踪粒子,得到前后两帧粒子图像,对图像中的粒子图像进行相关计算得到流场内各点的速度。文中主要介绍的是二维数字滤波方法在PTV流场测量结果后处理中的应用,通过数字滤波允许流速(可以看作U-V两方向的二维数值)中低频分量通过,同时阻尼和削弱高频分量,从而可以起到纠正错误流场数值的作用。文中以河北沧州港物理模型为例分析了Fourier变换(傅里叶变换)对PTV流场测量结果的滤波效果,并提出一套包含二维数字滤波、GIS(地理信息系统)流场显示在内的完整方案以便用于自动连续地处理流场测量数据。

Application of 2D numerical filter for velocity measurement technique in flow field of physical models

As a important velocity measurement technique,PTV is often used in ocean model experiment.PTV(Particle Tracking Velocimetry) is an non-intrusive optical flow measurement technique which supplies real-time velocity sample throughout 2D plane of the flow field.Using a numerical camera PTV get track of the tracer,some small,buoyant particles,which is scattered throughout the flow area.In this paper,the 2D numerical filter is applied to process data of PTV flow measurement.The 2D numerical filter permits the low frequency signal and damps or weaken the high ones,so the flow data can be corrected.Taking the example of physical model of Cangzhou Port,it is analyzed that the effect of applying Fourier Transform to PTV flow area.Finally,a set of system is proposed,including 2D numeric filtering and GIS flow area display,to process data automatically and continuously.