Effect of Propeller Slipstream on Heat-Exchanger Installations at Low Reynolds Number

An experimental program whose objective was an improved understanding of the effects of intermittent turbulence shed by a propeller on the aerodynamics of heat-exchanger installations at low Reynolds numbers is reported. The primary application is unmanned high-altitude atmospheric science aircraft, forming part of Old Dominion University’s effort to develop technology applicable to ERAST (Environmental Research Aircraft and Sensor Technology) class aircraft. Wind-tunnel results indicate that the propeller wake affects, but does not eliminate, laminar separation bubbles on a representative wing. Rather, the bubbles reform between wake passages, limiting the drag penalty caused by increased skin friction. Further, there appears to be a possibility of an enhancement in performance of suitably designed ducted heat-exchanger installations.