Prediction of compressibility effects using unstructured Euler analysis on vortex dominated flow fields

Two unstructured-grid Euler methods, one based on Cartesian grids and the other on tetrahedral grids, are applied to simulate vortex flows on two modular transonic vortex interaction wind-tunnel models. Both models have sharp-edged chined forebody and cropped-delta wing but different vertical tail arrangements: one has centerline tail and the other twin tail. The principal objective of the study is to assess the ability of the two Euler methods in predicting compressibility effects. The approach involves comparing computed forces, moments and surface pressures from the two methods with each other and with experimental data. In this paper, force and moment correlations are presented for symmetric and asymmetric flow conditions at 0.4 and 0.85 Mach numbers. In addition, surface pressure correlations are shown for the 20 angle-of-attack case. The results show that Euler methods can provide meaningful data to support preliminary design of fighter aircraft configurations whose aerodynamic characteristics are dominated by vortex flows in some parts of their flight envelope.