Gravimetric Investigation of the Particle Number Density Distribution Function in the High Speed Cascade Wind Tunnel for Laser Anemometry Measurements

摘要

Laser anemometry requires a minimum concentration of scattering particles in the flow. Before an L2F velocimeter could be used, the natural dust content in the low pressure tank of the high speed cascade wind tunnel had to be evaluated for this type of measurement. A Coulter counter was used for the necessary dust analysis by the gravimetric method. The result showed that the behavior of the particle number density distribution functions is dynamic and particularly dependent upon the flow velocity. A self cleaning effect, which is very important for laser anemometry, was found to make the tunnel dust free in the minimum amount of time, and a model concept was developed to explain the loss mechanism.