Performance Research Of Expansion Deflection Nozzle

Generally,the working altitude of launchvehicle andstrategic missile ranges from sea level to the near-earth space.It results in huge changes on nozzle working condition.The nozzle will suffer from theperformance penalty when working condition changes,that may even lead the SRM extinguish.With the ability of altitudecompensation,to a certain degree,Expansion-Deflection nozzle could overcome that difficulty.The ability of compensation is derived from the nozzle structure.Therefore,it is important to study the mechanism of Expansion-Deflection nozzle and the effect of different structure.And it can support on the design of E-D nozzle.This paper uses numerical simulation method to study the automatic compensation principle and workingmode of Expansion-Deflection nozzle.There are two types of E-D nozzle,annular throat E-D nozzle and discrete throat nozzle,have been discussed about the influenceof their structural parameters on nozzle performance.The structural parameters of annularthroat E-D nozzle include expansion ratio,convergence angle,initial angle of extension and the cone tail angle of center-body.The structural parameters of discrete throat E-D nozzle include the types ofE-D nozzleand the numberofthroat.The study shows that the performance of the two types of E-D nozzle is better performance than conventional nozzle and altitude compensation ability.The operating mode of the two E-D nozzles is a “closed” mode from the low altitude “open” mode to the high altitude.The effect of structural parameters to the annular throat E-D nozzle is as follow:Large expansion ratio shows better performance at high altitude,small expansion ratio shows better performance at low altitude;The best convergence angle is five degrees;the best initial angle is sixty-five degrees;the cone angle best angle is seventy degrees.Convergence angle and cone tail angle of center-body affect the performance of annular E-D nozzle at the low altitude.The initial angle affects the performance of annular E-D nozzle at high altitude.The effect of structural parameters to the discreteE-D nozzle is as follow:The performance of the discrete E-D nozzle with sixbanded throats is better than that of four.The performance of the discrete E-D nozzle with the banded nozzle throat is better than that of the circular throat.The type and the number of the throat mainly affect the performance of the E-D nozzle at low altitude.These parameters should be considered in the design of E-D nozzle.