Design and Execution of a First Hypersonic Boundary Layer Transition Experiment on Blunted Cones with Distributed Roughness at the IAI HYWT

摘要

It is a well known fact that hypersonic wind tunnels can not reproduce turbulent boundary layer on smooth model surface. This is a generic problem which has a negative impact on prediction of stability characteristic on any high velocity project development. To overcome the problem it is necessary to artificially induce the boundary layer to a turbulent state by means of surface roughness on the nose of the model at special positions. Computational fluid dynamics must play a major role in the development of hypersonic vehicles because ground test facilities, including the IAI hypersonic wind tunnel, are not able to fully simulate flight conditions. Numerically RANS computed trip database relying on an interface program to extract boundary layer edge properties and on existing transition criteria have been used to produce charts of the effective perturbation height taking into account the Reynolds and Mach numbers, as well as the bluntness ratio variations. In this paper, one aims at testing the trip database at the IAI HYWT on a five degree half angle cone with different bluntness ratios. The trips were manufactured using direct metal laser sintering technology well suited for rapid prototyping at low cost. This technology relies on 3D printing of specific patterns with deposition of aluminum/magnesium, stainless steel or titanium alloy powders. Finally the mechanical design and production of the wind-tunnel variable blunt cone was done at IAI. Enhancement of the schlieren diagnostic visualization techniques in use at IAI is also addressed. Therefore, a monochromatic laser used also for shock-tube experiment at BGU laboratory is introduced at the IAI HYWT as a new monochromatic light source and with fiber optics to reach higher resolution of the boundary layer flow structure in order to detect the onset of transition to turbulence. Results for a first batch of hypersonic wind tunnel experiments with preliminary analysis are also presented.