Secondary Flow Injection in Convergent-Divergent Nozzles for Fluidic Thrust Vectoring: A Review

Abstract

Thrust vectoring using fluidics has been attracting considerable interest as an efficient way to achieve compactness and agility compared to classical mechanical control of the nozzle in contemporary propulsion systems in aviation. In particular, among different possible strategies for thrust vectoring, secondary flow injection into the converging-diverging nozzles seems to be a potential way to control thrust vector via flow manipulation inside the nozzle instead of its mechanical displacement. This paper is a review of flow processes, design parameters, and performance of fluidic thrust vectoring using secondary flow injection in converging-diverging nozzles. It aims to outline the effects of nozzle pressure ratio, secondary/primary pressure ratio, mass flow ratio, position of the injectors, injection angle, and geometry of nozzles on shock formation, boundary layer separation, pressure field variation, and efficiency of vectoring. Main findings regarding the developments in dual-throat, bypass, serpentine, dual-bell, and reacting injection concepts will be reviewed, highlighting trends reported in recent literature. It has been demonstrated that effective thrust vectoring requires an optimal compromise between vectoring capability, thrust loss, and flow stability, where geometrical factors and fluidic control are considered to be design factors of coupled nature. Lastly, the article highlights some of the important areas requiring research, including the development of performance criteria, parametric studies, and experimental validation of data in the case of supersonic and real fluid flows. This review serves as a comprehensive guide for secondary injection in convergent-divergent nozzles.