Visualization and analysis on the thrust vectoring control in three-dimensional dual-throat nozzles

The dual-throat vectoring nozzle is an efficient technique utilizing less high-pressure secondary streams to control mainstream deflections flexibly. In this article, three-dimensional Reynolds-averaged Navier–Stokes simulations were performed using a commercial computational fluid dynamics program, and the numerical methods applied in this study were validated through comparison with the experimental results. Two parameters of the slot injector have been investigated, namely the incident angle of the secondary stream and the slot length-to-width ratio. Critical performance parameters have been quantitatively analyzed, involving the pitching angle, injected mass flow ratio, system resultant thrust ratio, and resultant pitching thrust efficiency. Furthermore, visual flow-field features are expounded using Mach number contours on the center-plane, Mach number contours on various slices, and streaklines. Some meaningful conclusions are drawn herein. The flow field in this three-dimensional dual-throat nozzle is not fully symmetric based on the reference of the center-plane. Consequently, a full domain is essential to capture the flow characteristics accurately, instead of a half domain. Although the pitching angle for the secondary stream incidence angle of 120° is the highest, comprehensive characteristics in terms of resultant pitching thrust efficiency and system resultant thrust ratio for 150° are more outstanding. The pitching angle, system resultant thrust ratio, and resultant pitching thrust efficiency increase with an increase in the slot length-to-width ratio for a constant secondary stream mass flow rate. Under the circumstance of a constant injection pressure ratio, the pitching angle increases with an increase in the slot length, whereas system resultant thrust ratio and resultant pitching thrust efficiency decline with an increasing slot length.