Aeroacoustic optimization of the NWB airline and turning vanes based on high fidelity CFD and acoustic simulation

In the period between beginning of the year 2009 and mid of the year 2010 the turning vanes of the aeroacoustic wind tunnel DNW-NWB have been successfully re-designed based on an optimization loop developed of the DLR Institute of Aerodynamics and Flow Technology in Braunschweig. A new wind tunnel was built relying only on computational fluid dynamics (CFD) which contradicts the classical approach based on experimental support by means of a pilot tunnel. The optimization chain discussed in this paper is based on an aerodynamic flow solution in a horizontal 2D cut through the airline and turning vanes. The objective is to minimize the energy loss through the vanes and is the basis for an optimization loop. Therefore the geometry and position of the vanes are parameterized in a CAD package and coupled with a hybrid unstructured grid generator. Further on, a ray tracer (program for simulation of lightening of a scene) is used as an acoustic analogy to simulate the acoustic behaviour of the turning vanes including the tunnel walls