在对于涉及有流体流动的许多错综复杂的现象进行力学研究时,人们总希望首先能对于研究对象获得一个直观的、全局性的认识,在可能的条件下,还希望能对流动的许多物理量如流动速度、方向、压力等进行直接的测量。由于流体力学绝大多数问题固有的非线性性质,使得实验研究具有了重要意义,而提供实验手段的显示和测量流场成为必不可少的环节。针对不同 In the mechanistic study of many intricate phenomena involving the flow of fluids, one always hopes to obtain an intuitive and global understanding of the subject at first and, where possible, one hopes that many physical quantities that flow, such as flow Speed, direction, pressure and other direct measurement. Because of the inherent non-linear nature of most problems of fluid mechanics, experimental research is of great significance, and it is an indispensable part to provide experimental means to display and measure the flow field. Different