Automatic Measurement of Velocity Distribution of Flow

Abstract

The method of speckle phtography is useful for measurement of velocity distritribution of whole flow field. However, the point-by-point measurement of local velocity by means of Young's fringe method takes much time. We discuss a method of automatic measurement in the present paper.
In order to analyze Young's fringes, we use two algorithms, one is FFT and the other is spatial fringe scanning (SFS). In the former, fringe spacing is determined by spatial frequency of first peak of the Fourier spectrum. In the latter, on the other hand, video signals are compared with reference periodic signals. Both of spacing and direction of fringes are determined automatically.