WALL-FLOW-DIRECTION PROBE FOR USE IN SEPARATING AND RE-ATTACHING FLOWS

The measurement of the exceedingly unsteady behavior of nominally two-dimensional, turbulent flows in regions of separation and reattachment is facilitated by the development of a new instrument; the wall-flow-direction probe which determines the instantaneous flow direction (upstream or downstream) in a thin layer of fluid very close to the wall. The probe was tested in low-speed, unsteady, separating and reattaching air flows. It appears to offer considerably more accuracy than other methods for the determination of time mean separation and reattachment points. In addition, the probe and its control circuits are relatively inexpensive and easy to construct.