Novel Concept of Capacity Enhancement on Supersonic Coflow Fluidic Thrust-Vector Control

In Coanda-effect-based coflow thrust-vector control systems, momentum exchange between the primary and secondary jets is dominated by the shear layer. This study proposes a novel concept that arranges protrusions at the lip of the secondary nozzle to enhance shear-layer mixing and improves control capability. High-resolution delayed detached-eddy simulation based on the shear-stress transport model is employed to solve the development and evolution characteristics of the flowfield. Results demonstrate that protrusions at the nozzle lip induce initial shear layer instability, amplified downstream by centrifugal effects, forming large-scale streamwise vortices within the shear layer. These vortices create spanwise and radial velocity inflections in the mean flow, triggering secondary instabilities. This process leads to a rapid instability of the shear layer, thereby enhancing turbulence fluctuations andmixingcapacity. For thrust vectoring, the unforced jet (no protrusions) experiences flow separation and control failure above a secondary jet pressure ratio of 2.0, and it yields a maximum vector deflection of 12.22 deg. Conversely, the forced jet (with protrusions) exhibits continuously increasing deflection within the simulated nozzle pressure ratio (NPR) range (NPRs ≤ 3.0), achieving 17.89 deg deflection, which is a 46.4% improvement. These findings indicate that enhanced shear-layer mixing extends the effective control range of NPRs and significantly improves thrust-vectoring capability.