Thrust Vector Control Based On Co-and-counter Flow

In the last decades,the in-depth study of various thrust vector nozzles has promoted the development of multi-functional exhaust nozzles.Multi-functional exhaust nozzles can work more efficiently for different flight conditions.The fluidic thrust vector nozzle has the simpler structure,convenient operation and better control effect in implementing the thrust vector process of supersonic aircrafts,rockets and guide missiles compared to the traditional mechanical thrust vector nozzles.In this paper,the co-flow and counter-flow thrust vector methods are taken as the research object.The effects of nozzle pressure ratio(NPR)and secondary pressure ratio(SPR)on the performance of thrust vector nozzles are studied by numerical simulations.The performance parameters,such as system thrust ratio,deflection angle and secondary mass flow ratio are analyzed.After the static performance analysis of the thrust vector nozzle is completed,the UDF function is used to change the nozzle pressure ratio(NPR)and the secondary pressure ratio(SPR)linearly.Analysis of the hysteresis in the changing of pressure ratio is finished.The main contents of the paper and the results achieved are as follows:(1)The co-and-counter flow thrust vector nozzle at M=2.5 is designed by MOC method.The calculation domain of geometric model is established by Gambit software.(2)Compared with the experimental data to verify the scientific rationality of the numerical simulation method.The comparison results show that there is an excellent agreement between the experimental data and numerical simulation.(3)The control variable method is used to change the nozzle pressure ratio NPR and the secondary pressure ratio SPR respectively.The change rule of the system performance is analyzed,such as the system thrust ratio,thrust vector angle and the secondary mass flow ratio.The results show that the thrust vector angle,the secondary mass flow ratio and the system thrust ratio decrease gradually as the nozzle pressure ratio(NPR)increases.For a high Mach number M = 2.5,a secondary mass flow ratio of less than 2.4% is required to achieve efficient thrust vector control.(4)The hysteresis is illustrated for changing the nozzle pressure ratio(NPR)and the secondary pressure ratio(SPR)linearly in the counter-flow thrust vector control.And the properties of the wall pressure distribution,deflection angle and the secondary mass flow ratio are analyzed.The parameter changes with the instantaneous pressure ratio.The results report that hysteresis curves of the deflection angle and the secondary mass flow ratio are forming when the nozzle pressure ratio(NPR)and the secondary pressure ratio(SPR)are changed linearly.