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 and mixing capacity. 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 ([Formula: see text]), 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 [Formula: see text] and significantly improves thrust-vectoring capability.