固体火箭发动机慢速烤燃特性及尺寸效应的影响机制研究

Cook-off is one of the important indicators to evaluate the low vulnerability of solid rocket motor(SRM). Slow cook-off is the most difficult thermal safety test for SRM. Establishing the cook-off theory and simulation model of the SRM is an effective way to reduce the cost and risk of cook-off experiments. However, at present, there is a lack of systematic study on the slow cook-off characteristics of the SRM. The differences of the cook-off characteristics between the scaling model and the actual model are not clear, which hinder the development of thermal safety evaluation technology of the SRM. This project proposes a multi-component and multi-reaction chemical reaction mechanism to describe the reaction process of butyl hydroxyl solid propellant, meanwhile, it establishes the coupled thermal-chemical-mechanical model of computing model of solid rocket motor during the heating process basing on cook-off theory and similarity criterion..This calculation model can systematically analyze the slow cook-off characteristics of the SRM under different scaling charge sizes, like cook-off time, temperature and response. Moreover, the results will clarify the effect of charge size on the cook-off characteristics. These provide a new understanding of the relationship between the slow cook-off characteristics and charge size of SRM. And more importantly, a simple and effective assessment procedure for thermal safety of the SRM will be established. The project helps to establish new methods and approaches for the design and thermal safety assessment of the SRM from a low vulnerability perspective.

烤燃安全性是评估固体火箭发动机低易损性的重要指标之一，其中慢速烤燃是发动机最难通过的热安全性试验项目，建立固体火箭发动机慢速烤燃理论和仿真计算模型是降低慢速烤燃试验费用和危险性的有效途径。但是目前针对固体火箭发动机整机的烤燃特性缺乏系统性研究，实验所采取的缩比模型与整机模型的烤燃响应特性的差异性尚未明确，制约了固体火箭发动机热安全性评估技术的发展。本项目结合慢速烤燃理论和相似准则，采用多组分多反应道化学反应机制描述丁羟基固体推进剂的烤燃反应过程，建立发动机烤燃过程中热、化学和力学变化和响应的耦合计算模型，系统分析固体火箭发动机的慢速烤燃响应时间、响应温度和响应程度等特性，阐明装药尺寸对固体火箭发动机慢速烤燃特性的影响规律，建立有效简易的慢速烤燃评估程序。研究结果将为固体火箭发动机烤燃特性与装药尺寸的关系提供新的理解，并从低易损性角度为固体火箭发动机设计和热安全性评估提供新的方法和途径。

慢速烤燃试验是评估固体火箭发动机及推进剂热安全性最为直观、有效的手段，但是其通常成本高、危险性较大，因此建立固体火箭发动机慢速烤燃仿真计算模型是降低热烤燃试验费用和危险性的有效途径，阐明固体发动机慢速烤燃响应特性和装药尺寸的关系是建立慢烤安全性评估程序的重要挑战。.本项目针对AP/HTPB丁羟复合固体推进剂，开展了热分解性能试验和小型热爆炸试验研究，采用自行设计的模拟固体火箭发动机烤燃装置，通过分析试验现象以及对推进剂内部多点进行温度监测和采集冲击波压强数据，阐述了不同装药尺寸下模拟固体火箭发动机慢速烤燃特性的差异性。建立推进剂的多步反应机理，对不同装药尺寸的模拟发动机慢速烤燃过程进行了数值仿真，获得了模拟发动机内部的温升历程和烤燃响应区域的形成过程。综合分析试验现象和数值仿真，阐明装药尺寸对发动机内部的热量传递和自热反应过程有着较大的影响，最终导致发动机的烤燃响应位置发生变化。烤燃响应位置和壳体约束条件共同决定发动机的烤燃响应程度。