EXPERIMENTAL STUDIES OF SHOCK WAVE/TURBULENT BOUNDARY LAYER INTERACTION IN HIGH REYNOLDS NUMBER SUPERSONIC AND HYPERSONIC FLOWS TO EVALUATE THE PERFORMANCE OF CFD CODES

Abstract

Experimental studies have been conducted and are continuing to obtain detailed surface and flowfield measurements in regions of shock wave/turbulent boundary layer interaction induced by incident shocks, compression corners, and steps and cavities to evaluate the modeling of turbulence and numerical techniques employed in contemporary RANS and LES/DES codes. The experimental studies are being conducted in the LENS supersonic and hypersonic tunnels at Mach numbers from 4 to 11 in high Reynolds numbers flows (up to 0.5 billion) to ensure that boundary layer transition has an insignificant effect on the size and fluctuating properties of the interaction regions. Measurements, which have been selected from a large database of two-dimensional flat plate and wedge shock generator configurations, are compared to RANS computations with contemporary SST and SA turbulence models. Measurements are also presented for two axisymmetric configurations: a large cone/flare model and a smaller cone/cylinder/flare model – the HIFiRE 1 flight test model. Flows over the large cone/flare model (L = ~ 9 ft) provided high Reynolds number turbulent boundary layers (δ = 3-5 inches) which enables us to probe the boundary layer to define the turbulent structures in the separation, reattachment, and recirculation regions. Here, boundary layer transition occurs very close to the sharp nosetip and has little effect on the size and unsteady structure of the separated interaction region. The measurements obtained on the HIFiRE 1 model at the cylinder/flare junction are compared with RANS calculations with Wilcox modifications to the SST and SA turbulence models. The measurements made on a new large cone/flare model as well as those being made on new hollow cylinder/flare and shock-generator/flare models are being prepared for a “blind” validation study similar to that conducted earlier with a double cone configuration for laminar separated flows. Measurements will also be made using the hollow cylinder configuration to study separated flows over backward facing steps and in open and closed cavities. Again, the objective of these studies is to provide detailed surface and flowfield measurements to evaluate and improve the models of turbulence employed in the RANS and LES/DES prediction techniques.