Effects and Flow Control Mechanism of Synthetic Jets in a Transonic Axial Compressor

To address flow instability induced by tip leakage vortex breakdown in high thrust-to-weight ratio aero-engine compressors, this study conducts numerical investigations into the DTR transonic compressor rotor. The unsteady evolution of the tip leakage vortex and the corresponding stall inception mechanism under near-stall conditions are revealed. Active flow control using single-slot and dual-slot endwall synthetic jets is further explored. Results show that an optimized single synthetic jet slot improves the compressor stability margin by 11.24% and design-point efficiency by 0.57%. To address the flow instability on this, synergistic excitation using two slots positioned at 25% and 50% axial chord length further suppresses leakage vortex breakdown and passage blockage, raising the stability margin by an additional 13.68% and efficiency by 0.72% compared to the optimal single-slot configuration. For the baseline compressor under near-stall conditions, tip leakage vortex breakdown occurs near 25% axial chord, causing severe flow deterioration. With synthetic jet actuation, low-energy fluid at the tip is blown away or sucked out, delaying vortex breakdown and reducing flow losses, thereby enhancing stability without compromising aerodynamic efficiency. The underlying mechanism is that, during the blowing phase, the jet splits the large-scale leakage vortex and removes the low-energy blockage region; during the suction phase, it extracts the fluid trapped in the tip clearance, preventing re-accumulation of low-energy fluid. These findings provide theoretical guidance for stall suppression and high-performance design of transonic compressors.