LDA MEASUREMENT WITHIN A VORTEX BOUNDARY LAYER GENERATED IN A ROTATING DRUM.

Abstract

Atmospheric vortices like tornadoes, whirlwinds and watersprouts have attracted the interest of many people because of their destructive nature. The essential data regarding distribution of velocity, pressure and energy are lacking as tornadoes destroy all standard measuring instruments. A detailed study is usually confined to a laboratory simulated natural vortex. The objective of the present work is to study the flow field of such a three-dimensional vortex boundary layer and effusing core at various Reynolds numbers Re (based on disk radius and free stream velocity of the edge of disk) which range from 5,000 to 30,000. This is done by measuring the three velocity components (tangential, radial and axial) in the flow field using a non-disturbing laser Doppler anemometer (LDA). From these measurements, a quantitative assessment of the flow characteristics and flow development is possible.