Numerical study of blunt leading edge separation on a 53 degree swept diamond wing (STO AVT-183) using the Edge and Cobalt flow solvers

This paper presents numerical results for a diamond wing test case using the FOI developed flow solver Edge and the commercial flow solver Cobalt. The results show the effect of grid resolution, turbulence modelling and temporal accuracy using RANS, URANS and hybrid RANS-LES methods on structured and unstructured meshes. The sensitivity of the solution to the free-stream Mach number, incidence and Reynolds number is also presented. The computed wing pressure distributions have been post-processed to give spanwise and chordwise distributions of the axial, normal and side forces which give an indication of the flow progression as incidence changes as well as showing the limits to attached flow on this wing. To verify the calculations, the results have been compared with wind tunnel test results. Wind tunnel corrections are also derived in order to compare the results provided with the free air numerical predictions. This paper concludes that when modelling this case with CFD, the details of the flow separation on the leading edge are extremely sensitive to the modelling approach taken. A large spread of results has been obtained although in some cases the results (both forces and pressures) match the experiment very well. There are also unresolved issues regarding what assumptions can be made about the experiment when conducting the CFD modelling, particularly regarding lift interference.