Thrust vectoring of dual-bell nozzles by secondary fluid injection for next-generation launch vehicles and missiles

Shock vector control (SVC) on a double-divergent nozzle (DDN) has attracted immense interest in recent years with the aim of achieving advanced maneuverability for the next generation of launch vehicles and missiles. These vehicles require thrust vectoring only intermittently, and the linear diverging sections of a DDN generate a non-axial thrust component during non-vectored operation. This leads to a substantial amount of thrust loss in DDNs during their non-vectored state. Hence, it becomes necessary to shift the focus of investigation beyond the linear diverging sections. In this context, the use of parabolic diverging sections, characterized by their small exit angles, can reduce the non-axial thrust component. Consequently, an analysis of SVC on a nozzle with two parabolic contours is an essential task. The present work reports a numerical study to understand SVC on a dual-bell nozzle (DBN) with parabolic contours. Keeping the nozzle area expansion ratio fixed, two different DBNs of inflection Mach number 1.5 are considered by varying the parabolic curvature of diverging sections. It is found that the thrust vector angle δ associated with the DBN configuration having a greater parabolic contour is very similar to that of a reference DDN. However, the thrust loss of this DBN configuration is significantly lower than that of the DDN. At a nozzle pressure ratio of 10, the thrust loss of this DBN configuration is ∼51.95% lower than that of the DDN. Hence, from the thrust vectoring point of view, a DBN is more beneficial than a DDN.