Cylindrical protuberance's effect on supersonic jet's flow control: Unveiling protuberance penetration and position on jet deflection through comprehensive turbulence simulation

Thrust vector control (TVC) through exhaust gas deflection is crucial for enhancing maneuverability, especially when aerodynamic control surfaces are ineffective. This study numerically investigates the influence of a cylindrical protuberance on the thrust vectoring of a supersonic jet as a passive, efficient TVC method. The effects of Nozzle Pressure Ratio (NPR), protuberance position, and penetration ratio on the nozzle exit flow, shock structure, and thrust deflection angle are analyzed. A convergent-divergent (C-D) nozzle is designed for a nominal Mach number of 2, and the three-dimensional, steady, compressible Navier-Stokes equations are solved using the SST k-omega turbulence model. Results reveal that protuberance-induced shocks and shock-wave/boundarylayer interaction significantly alter the flow structure and thrust deviation. The optimal protuberance position is found at 90 % of the divergent section length (Xp/L = 0.9), where increasing the penetration ratio (H/D*) up to 0.22 yields a maximum thrust deflection angle of 8.1 degrees. Additionally, higher penetration ratios generate stronger vortical structures, which, at H/D* = 0.2, become more prominent and susceptible to downstream jet-fin interactions. The thrust vector deflection exhibits a near-linear relationship with the penetration ratio, with thrust losses reaching up to 6.5 % at maximum penetration. These findings provide valuable insights into shock-vector control mechanisms, offering a benchmark for future aerospace propulsion studies and enabling the development of advanced TVC systems for high-speed applications.