Uncertainty Propagation in Integrated Airframe-Propulsion System Analysis for Hypersonic Vehicles

Air-breathing hypersonic vehicles are based on an airframe-integrated scramjet engine. The elongated forebody that serves as the inlet of the engine is subject to harsh aerothermodynamic loading, which causes it to deform. Unpredicted deformations may produce unstart, combustor chocking, or structural failure due to increased loads. An uncertainty quantification framework is used to propagate the effects of aerothermoelastic deformations on the performance of the scramjet engine. A loosely coupled airframe-integrated scramjet engine is considered. The aerothermoelastic deformations calculated for an assumed trajectory and angle of attack are transferred to a scramjet engine analysis. Uncertainty associated with deformation prediction is propagated through the engine performance analysis. The effects of aerodynamic heating and aerothermoelastic deformations at the cowl of the inlet are the most significant. The cowl deformation is the main contributor to the sensitivity of the propulsion system performance to aerothermoelastic effects.