Aerodynamic Loads of High Bypass Ratio Aeroengines: Installation Effects and Structural Implications

Abstract

This study investigates the aerodynamic loads and structural implications for a future high bypass ratio aeroengine. Reynolds averaged Navier-Stokes computations are performed across representative conditions and are validated against experimental data. The impact of airframe installation on the powerplant aerodynamic loads is quantified against an isolated configuration, and the underlying aerodynamic mechanisms are identified. The importance of the aerodynamic terms on key structural aspects is quantified through finite element analyses. Airframe installation modifies the powerplant aerodynamic loads through two fundamental mechanisms. First, at high-lift conditions, the increased airframe upwash changes the ingested streamtube and leads to pronounced flow expansion around the inlet lip. This results in increased inlet vertical loads by up to 9% of the net take-off thrust relative to the isolated geometry. Second, the elevated static-pressure field near the wing, combined with the swept-wing design, generates a strong inboard-outboard asymmetry on the powerplant. This leads to substantial changes in lateral loading on the thrust reverser, which are equal to 9% and 11% of the net thrust under take-off and sideslip conditions, respectively. Additionally, inclusion of aerodynamic loads from the isolated and installed powerplants increase the rear engine-to-pylon mount load by factors of 5.1 and 7.7 respectively, relative to a mechanical-only reference. This study quantifies for the first time the effect of airframe installation on the powerplant aerodynamic loads, identifies the underlying driving mechanisms, and demonstrates the structural significance of the aeroloads for future HBPR powerplant design.