무인 전투기의 배기 노즐 형상 및 Jet On/Off에 따른 열유동장 특성에 관한 전산 해석

Abstract

To reduce the IR signal of UCAV, geometrically deformed nozzles are often used in the propulsion system. However, the application of deformed nozzles can significantly affect the after-body shape of the flying vehicle, which may cause unexpected changes in the drag and thrust. In this study, the flow field of an unmanned combat fighter with a shape deformed nozzle in flight was analyzed using a CFD code. Special emphasis was placed on the effects of shape-deformed nozzle on the drag coefficient and thrust. In the case of shape deformed nozzle, the deformations of the nozzle affected the local flow field near the nozzle exit of aircraft and, as a result, induced a low drag coefficient, compared to the conventional axisymmetric nozzle. On the other hand, it was shown that the result in the thrust showed no significant difference, thanks to the smooth shape of deformed nozzle.