Flow Visualization of Cavitation With Particle and Bubble Image Processing

The new PIV image processing method is proposed to apply to cavitation flow field. Two CCD cameras take each high quality image shots utilizing the difference of the scatter light intensity between seeding particle and bubble. From the image of seeding particle, cavitation information such as the equivalent void fraction and the cavity boundary is obtained by using binary process for luminosity intensity. From both images of seeding particle and bubble, velocity information is obtained individually in regard to the inner or the outer area of the cavity by using cross correlation method and finally composed into one. For the evaluation of this PIV measurement and processing, the experiment was carried out about the wake vortex cavitation flow behind a wedge. Accordingly, the cavity boundary, the equivalent void fraction, the velocity vector and the vorticity were clarified and these reliability and validity were discussed in detail.