Aerothermal-structural Analysis of High-speed Flight Vehicles

There is currently a renewed interest in hypersonic flight vehicles after the success of the Australian HyShot 2 flight test in 2002 and the two NASA X-43a flight tests in 2004. The recent successful experimental flight test of the USAF's X51 waverider in May 2010 further advances the future of hypersonics flight vehicles. These hypersonic air-breathing vehicles are being investigated for cheaper access to space (such as launching payloads to low earth orbit), global reconnaissance / strike and high speed cruise flight. Hypersonic / high supersonic flight vehicles will experience very demanding heating and aerodynamic, as well as, aeroacoustic loads. Severe aerodynamic heating in hypersonic flight could cause melting and/or deformation of the structural components and this is currently one of the greatest challenges facing the R and D of future hypersonic vehicles. A detailed knowledge of the aerothermal environment of the flight trajectory is required in order to select appropriate materials and design the aerostructure of the vehicle. Although there is considerable knowledge in hypersonic aerothermodynamics, uncertainties in the prediction of the aerothermal loads and the structural response to these loads still exist. This paper will discuss methods for determining the aerothermal loads (such as from analytical predictions, CFD simulations, or wind tunnel data) and predicting the transient heating and structural response of the aerostucture. Aero-thermal-structural analysis of high-speed vehicles requires (1) realistic prediction of the aerodynamic heating loads and incorporation of these loads into the structural models and (2) transient coupled non-linear aero, thermal and structural analyses, to capture adequately the structural deformations and stresses in the aerostructure. Fluid-structure interaction also needs to be considered - the thermal response of the structure and the flow field properties are coupled. Our aerothermal-structural analysis capabilities1-3 have been utilised to support the thermal-structural design of scramjet engines in the University of Queensland's HyShot, DARPA's HyCause and the US Airforce / DSTO hypersonic programs.