Research On Steady-state And Transient Operating Characteristics Of A Plug-type Variable Thrust Solid Rocket Moto

The inherent attribute of the traditional solid rocket motor which is difficult to adjust thrust limits its application range.As a kind of solid rocket motor with adjustable thrust and good application prospect,the pintle variable thrust solid rocket motor can realize stepless adjustment of thrust within a certain range,which has attracted the attention of many researchers.Based on the thrust regulation principle,steady-state and transient operating characteristics of pintle motor,this paper discusses the influence law and mechanism of various factors on the flow characteristics of motor internal flow field and motor performance parameters by means of theoretical analysis,numerical simulation and experiment.The main research contents are as follows:First,the principle and characteristics of the pintle variable thrust solid rocket motor are studied deeply.The geometric model and specific parameters of the pintle motor are given,and the relationship between equivalent throat area and pintle stroke is determined by search algorithm.The complete internal ballistics model and transfer function model are established,and the formulas for calculating the steady pressure and the thrust after stabilization are given.The internal ballistics model and transfer function model are used to analyze the steady-state and dynamic characteristics of the motor,and the influence rules of various factors on the steady-state characteristics and dynamic process of the motor are obtained.The phenomenon of delay and negative adjustment in dynamic response process should be paid attention to.Second,steady-state numerical simulation method is used to study the steady-state flow field and motor performance of the pintle variable thrust solid rocket motor.A numerical model of steady-state flow field of pintle motor was established,the internal flow field of the motor was numerically calculated under various working conditions,and the changing rules of the motor flow field and motor performance were analyzed when the pintle was in different positions and the pintle was in different profiles.The basic flow characteristics and performance of the pintle motor were obtained.The influence law of pressure open-loop and close-loop control on motor performance is summarized.In addition,it is found that the selection of pintle profile has little influence on motor performance parameters,so the change curve of equivalent throat area should be specially considered in profile design.Third,based on the dynamic mesh method,the dynamic response characteristics of the pintle variable thrust solid rocket motor during operation are studied.The numerical calculation model of transient flow field of pintle variable thrust solid rocket motor considering the feedback process of burning rate was established.The numerical calculation of the internal flow field of the motor under various working conditions was carried out,and the changing law of the flow field during the pintle movement was analyzed.On this basis,the influence laws of pintle working state,pintle moving speed,pintle moving stroke and propellant pressure index on motor performance were obtained.It is found that the response of motor parameters falls behind the pintle movement,there is a large difference between the transient value achieved by the pintle reciprocating movement and the steady-state value achieved by the single path movement,and the thrust and the force on the pintle have significant negative adjustment characteristics.The moving speed of the pintle affects the adjustment process and response time of the combustion chamber pressure and motor performance parameters.The moving speed of the pintle increases,the response time of thrust extends,the negative adjustment increases,but the time to reach the stable value becomes shorter.In practical application,the appropriate moving speed of the pintle should be selected comprehensively.With the increase of pintle stroke,the response time of motor reaching the stable state also increases,and the thrust negative adjustment can be observed when the pintle stroke is larger.The variation range of combustion chamber pressure and motor thrust changes dramatically with the increase of pressure index.It can be seen that the selection of propellant pressure index is very important in the design of pintle variable thrust motor.The research results of this paper can provide reference for the improvement of thrust control model,further study of negative adjustment phenomenon,pintle profile design,transient simulation considering burning rate variation and motor test of pintle variable thrust solid rocket motor.