Mass injection and jet flow simulation effects on transonic afterbody drag

Abstract : An experimental investigation has been performed to determine the effects of boattail injection and jet flow simulation on the afterbody drag of a slender body of revolution in the transonic regime at zero angle of attack, such as engine nacelles and boattailed afterbodies with isolated engines. A correlation between sting and jet diameter has been established. The jet plume and the nozzle pressure ratio simulators have been found appropriate and useful as a testing technique. Boattail mass injection usually produces a drag coefficient reduction and is more effective at high nozzle pressure ratios. Boattail injection is more effective if used in regions of separated flow. (Author)