Research On Supplementary Combustion Technology Of Solid Rocket Motor Nozzle Expansion Section

Solid propellants are widely used in various strategic,and tactical missile weapons,with the advantages of simple structure,easy to use and easy to maintain.However,the impulse of solid propellant is low,a large number of combustible gases such as CO and H2 are contained in the gas,some of the energy is not completely released.In order to utilize this part of energy,it is considered to install a supplementary combustion device in the expansion section of the solid rocket nozzle to introduce compressed air into the expansion section of the nozzle,so that the gas that is not fully burned in the gas can be burned again to enhance the thrust and specific impulse.In response to these problems,based on numerical simulation the design and performance calculation of supplementary combustion device are carried out in this paper,the main contents are as follows:(1)I have designed two different types of supplementary combustion device for the expansion section of the nozzle,respectively,for the annular inlet and distributed inlet solid rocket engine nozzle expansion section additional combustion device.Both of these forms of afterburning devices can decelerate and pressurize high-Mach-flow air.After passing through the diffuser section and the isolation section,the air enters the nozzle and reacts with the gas.The distributed inlet supplementary combustion device can also be used to control the thrust vector by closing one of the inlets.(2)The outlet pressure of this two types of inlet ports should be greater than the gas pressure of the air injection position,and the velocity of the air flow should be close to the sound velocity,according to the requests of two kinds of combustion devices,the inlet was designed based on the theory of Oswatitsch,and the design process was programmed,and the performance of inlet was calculated theoretically.Based on the numerical simulation method,the design work condition of the air intake was calculated and compared with the theoretical calculation,which meets the design requirements.(3)The influence of different incident air amount,incident position and incident angle on the annular inlet supplementary combustion device effect was studied.As the amount of air injection increases,the thrust increases linearly,but the injection amount can not be increased indefinitely,otherwise it will cause the resistance caused by the afterburner to offset the thrust gain;With the air incident angle increases,the thrust first increases and then decreases,there is an optimal angle 28°;Within the air incident position tL d is range of 1.59~1.71,the position of air incident has little effect on the thrust gain.I calculated the integrated working state of inlet and nozzle,and analyzed the performance of nozzle and inlet under integrated working condition.(4)Aiming at the distributed inlet supplementary combustion device,the influence of different flight angles of attack on the working condition of the inlet and the supplementary combustion effect.The results show that the flight angle of attack will bring the lateral force,and the size is 0.35% of axial force.The forward torque produced by the lateral force will have adverse consequences,and measures should be taken to counteract the lateral force by the servo mechanism.A method of thrust vector control by closing one of the intake ports was studied.The lateral force of closure of an inlet is 1.46% of the axial force,and the lateral force generated by the closure of the two inlet is 2.09% of the axial force.Through the calculation and analysis of two different types of supplementary combustion device,it can be seen that the supplementary combustion of nozzle expansion section can improve the combustion efficiency of propellants,and reasonable setting of geometric parameters of the supplementary combustion device can improve thrust.The distributed inlet port can control the thrust vectoring by closing a certain inlet.