Local Piston Theory as an Alternative to Mesh Deformation: Slender Wing/Body Configurations

Abstract

The suitability of local piston theory (LPT) for modelling static loads on a deforming, low aspect-ratio wing in the presence of aerodynamic interference is investigated.Predictions using Euler-based LPT are compared to Euler solutions for the deformed geometry. Moderate to large deformations are investigated for the leeside wing on a cruciform wing-body configuration. It is shown that LPT is suitable even for large deformations, with the perturbation downwash-Mach number supersonic, provided that the loading induced by deformation is not dominated by interaction with body-vortices or other sources of aerodynamic interference. Second-order LPT is recommended for deformations producing downwash-Mach numbers approaching sonic. The influence of the choice of piston-theory coefficients is in producing an estimation band for the LPT load prediction, with insignificant influence on the load-slope in the present investigation. In conclusion, LPT is put forward as a viable alternative to mesh deformation towards reduction of the computational cost of aerodynamic load prediction for static aeroelasticity, provided that perturbation loads are dominated by local twist and not by vortex interaction.