Flow separation characteristics on diamond wing for various leading-edge roughness

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At wing configurations featuring moderate leading-edge sweep and blunt leading-edges, the flow separates in the leading-edge area at moderate angles of attack while the subsequent vortex formation extends only over a portion of the leading-edge. Towards the apex there is attached flow. The flow separation topology depends in particular on the Reynolds number and the roughness of the leading edge, i.e. whether the primary separation is associated with a laminar, transition or turbulent type boundary layer or a turbulent separation linked to a rough wall. In addition, due to the moderate leading-edge sweep, the partially developed vortex already burst after a relatively short development length. Apart from the actual leading-edge vortex (main vortex) there may be a further vortex-like flow separation along the inner wing part. In contrast to the cases with strong, fully developed leading- edge vortices, a precise analysis associated with partially developed leading-edge vortices and their main parameters justify detailed further research. Consequently, the objective of this project is to investigate the evolution and development of partly developed leading-edge vortices and corresponding flow separation as a function of the boundary layer state and leading-edge roughness using a generic diamond wing configuration. Complementary wind tunnel tests and numerical simulations have to be performed. Thus, features of the vortex structures and criteria for the transient characteristics are to be derived. Another objective is to evaluate the use of Navier-Stokes methods to this problem in terms of the quality of results, employing scale adaptive turbulence modeling and scale resolution techniques.