Reduced-Order Modeling of Turbulent Flows for High-Speed Aerothermoelastic Analysis

This work presents a reduced-order model that efficiently generates unsteady aerothermal loads due to turbulent boundary layers for high-speed aerothermoelastic analysis. This prediction capability enables high-fidelity aerothermoelastic and structural fatigue analyses over long durations with tractable computational costs. Unsteady pressures over deformed structures are modeled by decomposing a turbulent boundary layer into temporal and spatial components. An unsteady pressure history over an undeformed structure is first reconstructed by superimposing spectral proper orthogonal decomposition modes and frequencies. Subsequently, the reconstructed pressures receive spatial corrections to model regions of flow compression and expansion. Heat fluxes over deformed structures are generated using a superposition/interpolation method that applies spatial corrections to the heat fluxes of an undeformed structure. An assumption required to construct the reduced-order model is verified: spatial pressure fluctuations and heat fluxes are a linear function of the modal coordinates of structural deformations in the linear regime. The reduced-order model produces accurate spectral contents of pressure fluctuations, which is critical for accurate structural excitation prediction; however, the model slightly overpredicts the fluctuation magnitudes. Likewise, the model produces accurate steady heat flux loads. The results enable high-fidelity unsteady aerothermoelastic simulations at a computational cost reduction of five orders of magnitude.