Analysis of Flow Phenomena in a Highly Bent Engine Intake Duct for a Variation of Inflow Conditions

This paper presents results of experiments dealing with the steady aerodynamics inside an s-shaped aircraft engine intake duct under varying inflow conditions. The main objective is to investigate the influence of flight conditions appearing in the usual flight envelope of a slow flying aircraft platform. The used wind tunnel test bench consists of a duct only setup inside a pressure chamber which allows for variation of the inflow angle onto the duct and the induction of swirl onto the incoming flow upstream of the duct inlet. The evaluation shows a minor influence of the angle of attack onto the flow behavior inside the s-duct for the investigated angle range of −1.4° to +10°. The induced swirl distorts the total pressure distribution in the duct outlet plane. This distortion is not visible in the centerline wall pressure distribution on the top and bottom side of the duct in longitudinal direction. Since the DC60 and the pressure recovery also do not change significantly for the considered test cases a newly defined distortion descriptor called load vector