Experimental and Computational Investigations of a Normal-Hole-Bled Supersonic Boundary Layer

Abstract

A series of experiments have been conducted on a bleed hole array spanning the width of the Cambridge University Engineering Department supersonic wind tunnel at Mach numbers of 1.8 and 2.5. The wind tunnel was run with varying levels of suction, and the flow structure over the bleed array was subsequently mapped with a laser Doppler velocimetry system at a resolution of 0.25 hole diameters or better. The same wind-tunnel setup was simulated using the OVERFLOW Navier-Stokes equation solver. The information obtained was used primarily in qualitative comparisons of flow patterns. Overall good agreement was found in the definition of the expansion fan and barrier shock pattern produced by flow entering the normal holes, as well as three-dimensional flow patterns. Both studies agreed well in terms of measured mass flow rates, to within 1% of the boundary-layer mass flow. The presence of the barrier shock standing off the downstream edge of the bleed holes corresponded with a jet of upward flow, which may provide a mechanism for the generation of streamwise vortices.

Parameter Influence on the Porous Bleed Performance with & without Shock-Boundary Layer Interaction

“…In the past, several researchers investigated the effect of porous bleed experimentally. In contrast to real applications, the porous bleed regions in experiments are scaled in size, and only a small number of rows [1][2][3][4][5][6][7], or even a single hole [8][9][10], is investigated. Moreover, the porous bleed is only globally regarded, which means that only little information about the flow in the individual holes exists [11,12].…”

“…In contrast to experiments, numerical investigations make extracting the mass flow rates for individual holes feasible. Nevertheless, recent numerical studies [7,[14][15][16][17][18] lack in showing and analyzing the local mass flow rates. Also, the change of the flow field in the holes along the porous bleed is unregarded.…”