KARMAN VORTEX VELOCIMETER WITH A GENERATOR OF VERY SMALL DIAMETER

Abstract

Karman Vortex velocimeter which is applicable to liquid and gas was developed in this study. In this case, the Karman vortex generator of a very small diameter (φ0.1-0.7) is set perpendicular to the flow and a parallel laser beam (φ1) from laser diode passes through downstream of the generator. This beam is refracted by the density change resulted from the Karman vortex. The refracted light is detected by the photo-diode and the frequency is measured with FFT. The generator is heated to strengthen the magnitude of the signal. Three generators of three different diameter (φ0.3, 0.5, 0.7) are used to measure the velocities of three different points simultaneously and nine generators of same diameter (φ0.1) are used to switch the measuring point instantly by switching the electrical charge to the generators.