用Fourier变换莫尔法测量流体自由表面微幅波的振幅  

Fourier Transform Method for Measuring the Micro Amplitudes of Water Surface Waves

作　　者：王薇[1] 倪刚[2] 鄂学全[1] 

机构地区：[1]中国科学院力学研究所,北京100080 [2]北京空气动力研究所,北京100074

出　　处：《实验力学》2002年第4期425-432,共8页Journal of Experimental Mechanics

基　　金：国家自然科学基金资助项目(19972068)

摘　　要：采用一种非接触的光学方法傅立叶变换莫尔法(Fouriertransformmethod),结合数字图像处理技术,对微幅振荡的水表面波的振幅进行测量.它是对全场中每一个像素点进行测量,比接触测量法具有更高的灵敏度.它为微幅水表面波振幅的测量提供了一种手段.通过将计算机生成的周期性光栅图像经投影机直接投影到被测物体的参考平面,经CCD摄像头、图像板捕捉存储形成数字化的光栅图像,利用傅立叶变换莫尔法处理光栅图像,从而获得包含有水表面波的振幅的相位信息,再经适当的几何变换获得振幅信息.我们在垂直振荡装置上进行了不同激励频率和不同振幅的表面波的振幅测量.A noncontact optical technique, Fourier Transform method with a digital image processing technique is applied to measure the vibration amplitudes of the water surface wave generated in a vertical oscillating apparatus. It can obtain the depth information corresponding to each pixel point with high precision. This technique has higher accuracy than that of contact measurements, and offers a new way to measure the micro vibration amplitudes of the vertical water surface waves.In this research, first the grating images generated by a computer are directly projected by a projector onto a reference plane of the vertical oscillating apparatus, which is defined according to a liquid surface when the fluid of the vertical oscillating apparatus is stationary, i.e., h(x,y)=0. Then, those grating images before and after deformation are captured by a CCD camera followed by a graphical processing board to store as digital grating images. After that, FTP is applied to process these grating image, and phase information is yield, which includes the vibration amplitudes of the water surface wave. Finally, the phase information is transformed by appropriate geometrical transform to the amplitude value.

关 键 词：垂直振荡 水表面波 傅立叶变换莫尔法 条纹 图像处理 

分 类 号：O35[理学—流体力学] O43[理学—力学]