An oscillating hot wire for measurements in separated flows

Abstract

An oscillating-hot-wire system is developed to allow mean-flow velocity measurements in separated flows. Disturbance velocities can also be measured in regions of interest. An oscillating-arm assembly provides a directional bias to the hot-wire probe, and a linear-step assembly steps the probe through the boundary layer. These assemblies are mounted to a positioning plate which allows profiles to be taken at a discrete number of chord locations. Data sampling is computer regulated using a trigger pulse from an exterior source. A distance proximity probe gives the distance of the hot-wire probe from the model.

Series of mean-velocity profiles over an airfoil are measured for R_C 150,000, 200,000, 250,000, and 300,000 with a= 14° and for R_C = 200,000 and 250,000 with α= 12°.