MEASUREMENT AND VISUALIZATION OF TWO-DIMENSIONAL VELOCITY DISTRIBUTION BY THE LASER SPECKLE PHOTOGRAPHY USING A He-Ne GAS LASER (1ST REPORT, APPLICATION TO THE FREE CONVECTION FIELD AROUND A VERTICAL PLATE IN AIR AND MEASURING ACCURACY).

The speckle photography technique is one of the most novel velocity measurement methods. This study examines the possibility that this technique will become practically applicable. In this study, this technique is applied to the laminar-free convection field around a uniformly heated vertical plate in air. Moreover, a He-Ne gas laser is employed as the light source in order to enhance the validity of this technique. The measuring results agree with a similar solution within plus or minus 10% at the local velocity u(y) equals 0. 057 approximately 0. 185 m/s. It becomes clear that this technique using a He-Ne gas laser can obtain a whole instantaneous two-dimensional velocity distribution with fair accuracy.