Dynamic flow behaviors of an inlet isolator in embedded rocket-driven mode transitions

Abstract

The dynamic flow behaviors, as well as the propagation and coupling of regulation information, in a rocket-based combined-cycle inlet isolator during the ejector-to-ramjet mode transitions driven by different embedded rocket control methods, are numerically investigated. The key parameters of compression power, Mach number, and pressure ratio are used to illustrate the operation performance of the inlet isolator. The rocket jet induces strong shocks while inhibiting the shock/boundary layer interaction in the jet-covered region. The coupling of the rocket jet shear and back pressure is linked to the formation of wall flow separation. The parameter distributions are greatly influenced by the destruction of shock structures, which is crucial for the stability of supersonic flowfields. The continuity of the jet boundary is disrupted by the regulation of the embedded rocket, and an increase in the throttle level will further intensify the breakup. Back pressure propagation is limited by the rocket jet and is constantly matched with the jet and mainstream until the rocket's influence domain reaches stable. The “high throttle-maintaining” and “direct-shutdown” mode transitions tend to induce oscillations in the isolator compression performance. In the “direct-shutdown” mode transition, the vorticity proportion in the combustor is unstable and the flowfield disorder is high. In the “high throttle-maintaining” mode transition, the vortex generation level is relatively stable and high, while the entropy proportion fluctuates strongly and at a high level. By adopting the “medium throttle-maintaining” mode transition, the entropy and vorticity proportion levels are relatively stable, which is conducive to the stability of mode transition.