Design,Performance And Application Of AP-based Thermal Balance Propellant

A solid propellant is an energetic material that contains both an oxidant and a reducing agent.Therefore,once a solid propellant is ignited,its combustion will continue until the propellant is burned out,and it can not be interrupted.This also makes it difficult for solid rocket engines to achieve multiple start-stops.Based on this requirement,this paper analyzes the combustion mechanism of AP-based composite propellants.From the perspective of the endothermic and exothermic balance of the propellant combustion surface,it is preferred to use WA and WC as thermal balance materials to control the combustion heat balance of AP-based composite solid propellants.A thermally balanced propellant with combustion and flameout characteristics was prepared.The propellant performance was studied using thermal analysis,constant pressure combustion experiment,and thermal conductivity analysis.The application of this propellant was explored in combination with a small-size charge laser ignition experiment and a ?75mm engine.The main research work is as follows:(1)Using DSC and TG thermal analysis methods,the thermal decomposition characteristics of AP and thermal equilibrium materials and the influence of different thermal equilibrium materials on the thermal decomposition of AP were studied.The results show that the thermal equilibrium material contains multiple endothermic decomposition stages;with the increase of the thermal equilibrium material,the first partial liberation heat peak of the AP moves to the right,the second partial liberation heat peak moves to the left,and the AP partial liberation enthalpy change decreases;Kinetic analysis showed that the thermal equilibrium materials inhibited the first stage and the second stage of the AP's heat release.Four kinds of thermal equilibrium materials could inhibit the exothermic decomposition of AP;(2)Based on the AP / HTPB propellant system,through the introduction of thermal equilibrium materials,combined with theoretical calculations of the explosive heat and temperature of the propellant,the design and research of the thermal equilibrium propellant was carried out.The results show that with the increase of the proportion of the thermal equilibrium material,the theoretical heat released by the AP-based thermal equilibrium propellant and the temperature gradually decrease in a linear relationship without considering other inhibitory effects,and after linear fitting,the minimum AP decomposition is achieved.The amount of heat balance material needed to add 1068.1k J / kg is 42%,25%,35%,and29%.The normal pressure ignition combustion experiments of propellants show that under the control of heat balance materials,the propellant samples are given to the ignition source.After that,it can be ignited,the fire source is removed,and the propellant sample is extinguished,and the design effect is initially achieved.Therefore,designing thermal equilibrium propellants based on WA and WC;(3)The AP-based thermal equilibrium propellant was prepared through process and formula optimization,and the properties of the AP-based thermal equilibrium propellant were studied by using burning rate analysis,DSC,TG,and thermal conductivity analysis.The results show that with the increase of thermal equilibrium materials,the constant pressure combustion rate of thermal equilibrium propellants gradually decreases,and the thermal equilibrium propellant has a critical flame pressure of 7.5 MPa,and the thermal equilibrium control is better.,The larger thermal conductivity makes the decomposition endothermic effect stronger,and at the same time the heat of AP decomposition is reduced;(4)A small-size burner and a ?75mm engine were used to perform laser and engine ignition flameout tests on the AP-based thermal balance propellant formula.The results show that after the laser ignition is given,the thermal equilibrium propellant can ignite in a small-sized burner,stop the laser ignition,and the propellant is extinguished.With the increase of the additive ratio,the flameout delay is shortened,and it has the ability to start multiple ignitions and flameouts;In a ?75mm engine,the thermal equilibrium propellant is not easy to be ignited,and related applications need to be further explored.