Investigation on the mechanism and method of wide adaptability turbine aerodynamic regulation

Variable-cycle engines (VCEs) require precise, wide-range turbine flow control while avoiding the complexity, weight, and durability issues of conventional geometric regulation. This study investigates suction-side slot injection as an aerodynamic regulation approach on the VKI-LS89 transonic nozzle guide vane profile. Steady 2D blade-to-blade RANS simulations are performed in a cascade configuration with spanwise periodic boundaries, and the baseline flow is validated against the MUR45 experimental condition. A parametric study is conducted to quantify how slot width, slot position, slot angle, and relative jet mass flow rate (m˙_inj) affect turbine flow capacity, total pressure loss, and internal flow features. Among the parameters tested, slot position exhibits the highest sensitivity, with the strongest regulation obtained when the slot is located at x/C≈25%−35% (slightly upstream of the aerodynamic throat). Slot angle and jet mass flow show systematic trade-offs: counter-flow orientations and higher injection rates enhance blockage but increase mixing and wake loss. For a representative case with a perpendicular slot (θ_AFC=0^∘) and m˙_inj = 5%, the inlet mass flow is reduced by 10.41%. Mechanistically, slot position governs where blockage forms, slot angle controls the jet-mainflow interaction mode, and jet flow rate sets the intensity of momentum/energy exchange; together they regulate flow stability and loss growth. Balancing regulation effectiveness and loss penalty, for the present validated steady 2D blade-to-blade simulations on the VKI-LS89 profile and within the examined parameter space, a practical compromise is achieved with Δn/o ≈ 15%-26% (15.4%-25.8% in the tested cases), x/C≈ 0.25–0.35, θ ≈ 0°, and m˙_inj ≈ 10%-12%. These numerical recommendations are case-specific and intended as guidance for further study; they should not be interpreted as global optima and require validation by three-dimensional, time-accurate simulations and experimental tests prior to engineering deployment.