Performance of the wing integrated heat exchanger of the Theseus UAV

Abstract

Experimental data for the heat transfer, pressure distributions, lift and drag coefficients, and flow visualization have been obtained for a 30% scale model of the integrated wing-radiator-cowlflap geometry as designed for the Theseus high altitude unmanned aerial vehicle (UAV). Most results have been obtained at a nozzle-to-radiator area ratio of An/Aro = 0.2, for two different nondimensional radiator pressure drop values. Lift and drag coefficients for the case with heat transfer agree well with computational fluid dynamics (CFD) results due to Drela, the original designer of the heat exchanger and airfoil geometry. The lift coefficient is reduced for the heated case relative to the unheated case. The drag coefficient is low for angles of attack between zero and six degrees, but increases for angles of attack above this range, due to the onset of trailing edge stall on the airfoil. Unheated results also show a drag increase for angles of attack below this range, due to flow separation on the cowl and cowl flap mounted beneath the radiator.