EFFECTS OF STRAKES ON A GLANCING SHOCK-WAVE TURBULENT BOUNDARY-LAYER INTERACTION

Glancing interactions, between a turbulent boundary layer and shock wa ves generated bg an unswept sharp fin with one of five different strak es, were examined at Mach 2.46. The aim was to investigate the effects of the strakes on the interaction behavior. The experiments involved surface pressure measurements, surface oil-flow patterns and laser-lig ht sheet pictures. An Euler computational fluid dynamics solver was us ed to help understand the inviscid-shock structures that play an impor tant role in defining the interaction strength. The results show that a properly designated strake, which covers the whole of the Foot chord of the fin, has a weakening effect on separation. When a sharp fin is modified using a strake, the shock wave from the strake leading edge (strake shock) intersects the shock from the unmodifred part of the mo del (fin shock) and bends it strongly towards the model. In order to p revent separation, a strake must be tall enough to prevent the fin sho ck reaching the wall before the fin trailing-edge location. At the sam e time, the strake must be slender enough so that the strake shock its elf does not cause separation. Based on these conditions, the strake d imensions needed to prevent separation have been predicted.