Control of a Mach reflection-induced interaction using an array of vane-type vortex generators

Abstract

An experimental investigation was conducted to control a Mach reflection (MR)-induced flow separation in a Mach 2.05 flow using a 18∘ shock generator (SG). The study was extended to four SG exit heights (g / w) of 0.87, 0.81, 0.725, and 0.66 primarily to study its effect on the extent of flow separation as well as on Mach stem height, with and without control. Two vane-type vortex generator configurations, namely the ramp vane (RV) with device heights h/ δ= 0.3 , 0.5 , 0.8 , and 1.0 and the rectangular vane (RRV) with h/ δ= 0.3 and 0.5, were studied for control. Each control device array was implemented 10δ upstream of the separation location for no control. For stable MR interactions (i.e., g/ w= 0.87 , 0.81), the extent of separation and the reattachment shock strength are seen to decrease with increase in RV height (with h/ δ= 1.0 device showing 17% reduction). However, for unstable MR condition (i.e., g/ w= 0.725), RV devices of h/ δ= 0.8 and 1.0 become ineffective. The RRV2 device (h/ δ= 0.5), on the other hand, was found to be more effective in reducing the extent of separation in both the stable (31%) and unstable (24%) MR conditions. The effectiveness of each control device is also accompanied with an increase in height of the Mach stem. This is, however, not seen as a serious limitation since in such strong interactions it is more important to prevent or avert an intake unstart condition. The separation shock unsteadiness or the σmax/ Pw value, on the other hand, is seen to increase considerably with controls and seems to be almost independent for h/ δ≥ 0.5.