Active Jet Control of Transonic Backward-Facing Step Flow With Pressure Sensitive Paint Measurements

This study investigates the effects of active jet control on a backward-facing step flow at Mach 0.9 using Pressure Sensitive Paint. Active jets were injected at pitch angles of 0° and 45°. Jet-to-total pressure ratios (P₀j/P₀) of 0.5, 1.0, and 2.0 were tested. Results show that a pressure ratio of 1.0 combined with a 45° pitch angle provides the most effective control. This configuration achieves enhanced pressure recovery. It also improves near-wall flow stability and promotes earlier flow reattachment. In contrast, jets with lower (0.5) or higher (2.0) pressure ratios offer less benefit or induce additional flow disturbances. These findings highlight the importance of optimizing jet angles and injection strength for effective transonic flow separation control.