Visualization of Low-speed Flow using Suspended Plastic Particles

Abstract

PHOTOGRAPHY of particles suspended in a fluid often gives a more complete and easily comprehensible record of the events associated with the passage of fluid around an object than can be achieved through measurements of force, velocity, or pressure. In practice, however, smoke trails and most other methods of flow marking^1–4 are both cumbersome and non-quantitative. In response to the problem of recording flow patterns around airfoils at Reynolds numbers of about 100, we have devised a new technique, using plastic particles suspended in a revolving bowl of brine and illuminated by pulses of light. This system produces photographs of steady flow patterns at Reynolds numbers between 30 and 300, with both speed and direction of flow indicated in the pictures (Fig. 1).