An Experimental Investigation into the Use of Hot-Film Anemometry to Measure Vortical Velocity Behind a Pitching Wing

Much has been done in the instrumentation of airfoils and wings to obtain surface pressure data in support of the characterization of the transient lift augmentation due to unsteady aerodynamic effects. These effects have usually been the result of rapidly rotating wings to high angles of attack or periodic oscillation. Integration of the acquired pressure coefficients leads to the airfoil or wing coefficient of lift. Researchers Walker and Robinson asked for other researchers to explore the use of hot-film anemometry as a confirming technique. In such a role, the anemometry is capable of mapping velocity vs. position, which is used to compute circulation via a line integral. The computed circulation is directly proportional to lift coefficient for a given freestream velocity. This paper describes the investigation into the use of hot-film anemometry, identifies strengths and weaknesses of the approach, and makes specific recommendations regarding its use.