【作者】 梁华；

【导师】 周长省； 鞠玉涛；

【作者基本信息】 南京理工大学 ， 机械电子工程， 2009， 博士

【摘要】 固体冲压发动机系统结构简单、使用方便、比冲较高、工作可靠,具有广阔的应用前景。在固冲发动机工作过程中,补燃室内要进行富燃燃气的二次燃烧,所以补燃室内壁处于大量高温高压燃气的包围之中,燃气和室壁之间存在着十分强烈的热量传递,同时冲压发动机补燃室内又处于富氧状态。由于高能推进剂和高强度材料被广泛采用,热强度问题也由于传热量的增加和壳体的减薄而变得更加的突出。若热防护技术不过关,将导致发动机补燃室烧穿而失败,必须给予高度的重视,并加以重点解决。因此,开展固体冲压发动机补燃室内绝热层传热烧蚀特性研究,就显得非常有意义。本文以某冲压增程弹冲压发动机补燃室内绝热层为研究对象,采用数值模拟与试验相结合的手段,对冲压发动机补燃室内绝热层的传热与烧蚀特性进行了研究。主要研究内容为：(1)建立了冲压发动机补燃室内纯气相带化学反应流场的物理模型,采用含κ-ε双方程模型的湍流时均方程组,给定方程组的边界条件,对补燃室内化学反应流场进行了数值模拟,给出了补燃室内燃气参数值,如温度、速度、压力等,根据燃气参数并进一步计算出了燃气与壁面之间的换热系数,为后续冲压发动机补燃室内传热烧蚀计算提供准确的热载荷边界条件。(2)建立了冲压发动机补燃室内绝热层传热烧蚀物理模型,提出了针对该模型的计算处理方法和定解条件,研究了绝热层材料内部具有热解反应的传热特性与富氧燃气环境下含热化学反应和气流剥蚀得绝热层材料烧蚀特性。通过数值计算,得到了冲压发动机补燃室内绝热层温度分布以及烧蚀率。(3)对绝热层材料进行了热重分析试验、燃气发生器试验和冲压联管试验,分析得到了绝热层材料在冲压发动机补燃室内的传热烧蚀机理,测试了不同燃气参数对绝热层传热烧蚀的影响。并提出低导热系数材料的背面温度的测试方法和修正方法,在试验过程中对绝热层的背面温度进行了测量,对试验后的绝热层进行烧蚀量的测量,对烧蚀后的试样做扫描电镜微观分析和元素成分分析,为绝热层的传热烧蚀模型的建立、计算及验证提供试验数据。通过本文研究,建立了冲压发动机补燃室内绝热层传热烧蚀数学物理模型,以及针对该模型准确有效的计算程序,得到了冲压发动机补燃室内绝热层传热烧蚀特性,以及燃气参数对传热烧蚀特性的影响规律。本文的研究工作对冲压发动机补燃室内绝热层的设计和应用具有指导意义,同时为后续开展该类绝热层的传热烧蚀机理研究提供了理论参考依据。更多还原

【Abstract】 Because of the advantages such as simple structure, convenient usage, high specific impulse and reliable working performance of solid rocket ramjet, it will have a wide application for the solid rocket ramjet. During the working time, the oxygen-poor fuel gas from the generator and the air from the inlet mixed with each other first, and then combusted again in the second combustion chamber, so the inner wall of second combustion chamber is surrounded by the fuel gas with high pressure and high temperature. There is strong heat transfer between the fuel gas and the inner wall. And it is oxygen-rich in the inner environment of chamber. Because of the use of the high energy propellant and the high strength material, along with the more heat transfer and the reduction of ramjet shell, the hot strength will be more serious. The unfitted thermal protection system will result in the burn through of the chamber and the failure of the ramjet. So, it must be pay more attention. Therefore, it is very important and necessary to specially research the heat transfer and ablation properties of insulation in ramjet chamber. Aiming at above problems, in this thesis, heat transfer and ablation properties of insulation in ramjet chamber are studied by using the numerical simulation method and tests. The main researches are as follows:(1) Based on k-εtwo equations, the physical model of pure gas phase flow fields with reacting in the ramjet chamber and the relevant boundary conditions and numerical method are given. By the numerical simulation, the flow field structures and the fuel gas properties such as temperature velocity and pressure in the ramjet chamber are obtained. According to the fuel gas properties, the heat transfer coefficient between the fuel gas and the inner wall of chamber can be computed. These data is helpful for the researching on the numerical simulation of heat transfer and ablation of insulation as the heat load.(2) Establishing the physical model of the heat transfer and ablation of insulation in the combustion chamber, the corresponding boundary conditions are proposed and the numerical simulation is carried out. The heat transfer with pyrolysis and ablation under oxygen-rich environment are researched. The temperature contour in the insulation and the ablation rate can be obtained by the numerical simulation. The main influence factors of the material on the heat transfer and ablation and the relations between those factors are analyzed.(3) The thermal gravity test and gas generator test and connected pipe test for ramjet is used for the heat transfer and ablation test of insulation in chamber. The heat transfer and abalation mechanism are obtained. The methods of temperature measurring and temperature amending are presented. During the working time of the ramjet, the back-face temperature of the thermal protection material is measured. After test, the ablation rate of insulation is measured too and the scanning electron microscope of samples was investigated. So all of them can provide effective test data for the establishment and computation and validating of heat transfer and ablation of the chamber insulation.This paper researches the heat transfer and ablation properties of the insulation, and establishes the numerical and physical model of insulation, and forms the compute program of the insulation heat transfer and ablation model. And the influence on the heat transfer and ablation by the properties of combustion gas is obtained. These results are significant to the design and application of insulation in ramjet combustion chamber, and supply a fundament to the theory research of heat transfer and ablation mechanism of this kind of insulation.更多还原