The linear control characteristic of the multi-wall passive fluidic thrust vectoring nozzle

The thrust vectoring technology is the key technology of high-performance aircraft, which can be divided into the mechanical and the fluidic thrust vectoring technology. The fluidic thrust vectoring technology has advantages of simple structure, fast deflection response and low energy consumption, so it has been widely studied. However the problems of jump and nonlinearity of the control law exist in the current rectangular fluidic thrust vectoring nozzles. Meanwhile the maximum deflection angle is small, which seriously limits the engineering application of this technology. A new type of the rectangular multi-wall passive thrust vectoring nozzle is developed in this paper. In order to figure out whether this new nozzle can realize the vector control of the jet with high linearity and larger deflection angle, two control strategies of the multi-section wall under multi-wall passive secondary flow and the variation of the initial passive secondary flow rate are employed. The characteristics of the dynamics and flow field of the jet are studied by means of experiment and numerical simulation. The results show that these control methods improve the linearity of the control law of the force vector angle, and the effective deflection force vector angle is increased. The linearity of the control law increases from 62% to 90.8%, and the maximum deflection force vector angle increases from 18° to 22°. When the initial inlet and outlet area ratio of the passive secondary flow is 1.16, the line-arity is further increased to 94.9%. It is found that there is no obvious separation bubble structure near the wall of the nozzle during jet deflection, which preliminarily explains the principle of the linear continuous control law of the nozzle.