Flow Separation Control of an Ultra-compact S-shaped Convergent-divergent Nozzle Using the Blowing Method

To enhance the aerodynamic performance of an ultra-compact S-shaped convergent-divergent nozzle and mitigate flow separation, numerical simulations were conducted using FLUENT software. The study employed the k-ω shear stress transport turbulent model to investigate a flow control method involving blowing. Detailed analysis was performed on the impact of blowing position, angle, and pressure ratio on controlling flow separation. The findings indicate that as the blowing position moves backward, the flow separation area diminishes. Additionally, downstream flow separation ceases at smaller blowing angles within the separation zone. However, excessively large blowing angles tend to create an “aerodynamic wall,” causing significant upstream flow loss and nozzle performance degradation. Enhancing the blowing pressure ratio, given proper mixing with low-energy fluid and no interference with the main flow, can improve the nozzle's aerodynamic performance. Under the optimal blowing scheme, the total pressure recovery coefficient and thrust coefficient are increased by approximately 0.52% and 3.75%, respectively, when compared with those of the reference nozzle.