【作者】 郭健；

【导师】 张为华；

【作者基本信息】 国防科学技术大学 ， 航空宇航科学与技术， 2007， 博士

【摘要】 固体燃料冲压发动机具有比冲高、结构简单、可靠性高、安全性好等优点,在未来超声速导弹和增程炮弹中具有广泛应用前景。本文采用理论研究、数值模拟和试验研究相结合的方法对发动机内部燃烧流动过程进行深入研究,进而开展工作过程仿真和一体化设计优化技术研究。基于HTPB热分解及反应过程分析,建立了12组分、17反应的化学反应模型。采用二阶矩湍流燃烧模型,有效克服了常用的E—A模型、简化PDF模型等均无法正确描述固体燃料冲压发动机中化学反应速率和扩散速率处于同一量级的现象。在此基础上,采用雷诺平均N—S方程、BSL两方程湍流模型、化学非平衡方程和二阶矩湍流燃烧方程,建立了描述固体燃料冲压发动机燃烧室、补燃室和喷管内部燃烧流动过程的物理数学模型。在数值模拟中,采用计算药柱表面层流底层导热率的方法计算燃面退移速率,与采用经验公式计算对流换热系数的方法相比更能反映出传热过程物理本质,有效地提高了计算精度。运用时间相关的LU-SGS方法,采用强耦合的全隐式有限体积进行离散,其中无粘对流项采用三阶MUSCL型差分的AUSMPW+格式,并应用最大特征值分裂,将矩阵运算转化为代数运算,大大缩短了计算时间。在此基础上,编制了数值模拟软件。通过数值模拟分析了台阶高度、空气总温、燃烧室空气流量等对发动机性能的影响规律。在国内首次完成了无氧化剂固体燃料冲压发动机试验,发动机点火可靠,工作稳定。在国内首次采用三组元燃烧空气加热器和垂直软管连接方式,建立了新型固体燃料冲压发动机试验系统,推力测量精度高于采用轴向迷宫式密封连接方式;空气加热系统工作可靠性高,加热效率高。对不同总空气流量、燃烧室空气入口直径、燃烧室空气流量与总空气流量之比开展了试验研究。试验研究表明,总空燃比、补燃室压强和比冲随总空气流量减少而下降;减小燃烧室空气入口直径或增加燃烧室空气流量都使燃气流量上升,总空燃比和比冲下降。在工作过程仿真分析时,考虑到辐射传热和壁面加质的影响,建立了燃面退移速率工作过程仿真模型。在此基础上,建立了固体燃料冲压发动机工作过程仿真模型,编制了仿真计算程序,详细分析了固体燃料冲压发动机不同工况和结构参数对性能参数的影响规律。分析研究表明,在飞行速度与发动机效率之间存在平衡关系,导弹总体设计时需对这两个参数进行优化;通过选择合适设计点,以保证导弹巡航飞行时推力平稳;固体燃料冲压发动机设计飞行工况为稳定工况,能根据巡航导弹飞行高度和速度变化进行自适应调节。在发动机工作过程仿真分析的基础上,选取五个主要参数作为优化变量,建立了固体燃料冲压发动机一体化设计优化模型,结果表明优化方案可使导弹飞行距离提高24.8%。更多还原

【Abstract】 Because of the virtues, such as high specific impulse, self-adaptive control property, simple structure and high security et., the solid fuel ramjet has extensive application foreground on supersonic missile and added-range projectile. The study on the combustion and flow behavior inside the motor is carried out through theoretical study, numerical simulation and experimental study. Moreover, the study on the simulation of the solid fuel ramjet operation process and the optimization of the motor design is carried out.On the basis of the analysis of the decomposition and reaction process of HTPB, the 12 species 17 steps model is used. Because the chemical kinetics velocity and diffusion velocity are in the same magnitude in the solid fuel ramjet, the models, such as the E-A model, fast reaction simplified PDF model and finite reaction velocity simplified PDF model, can not mirror this phenomenon. Comparing with other models, the second-moment model is selected. Thus, the physicomathematical model is established to describe the combustion and flow behavior inside the combustion chamber, the second combustion chamber and the nozzle of the solid fuel ramjet. The three-dimensional Favre-averaged compressible turbulent N-S equations are used as the governing equations of the reacting flow, and the BSL two-equation turbulence equations are used for the turbulent flow, and the chemical non-equilibrium equations are used for the reaction rate, and the second-moment model is used for the turbulent combustion.The key to numerical simulation is the calculation of the fuel regression rate. In many literatures, in order to achieve the fuel regression rate, the convective heat transfer coefficient is calculated to get the heat exchange rate, using many empirical formula and methods. In the thesis, the heat conductivity of the laminar sub-layer on the surface of the grain is calculated, which reflects the physical essence of the heat transferring. But it demands the higher computational accuracy. Time-dependent LU-SGS method and close coupled full implicit finite volume scheme are used. The AUSMPW+ based on the three-order MUSCL difference scheme is used for the inviscid operator, and the maximum eigenvalue splitting method is used to convert matrix operation to algebraic operation in order to shorten the computing time. Based on the above, a numerical simulation computing program is coded. It is analyzed the influence of the parameters, such as the step height, air total temperature, combustion air flux et.For the first time in domestic, the solid fuel ramjet experiments with nonoxidizer propellant are performed. The experiments results prove that the ignition is reliable, and the motor works stably. A new style solid fuel ramjet test system is established adopting the three species combustion-air heater and vertical hose connection mode for the first time in domestic. The accuracy of thrust measurement of this test system is higher than that of the test system adopting the axial labyrinth seal connection mode, and the heater system has the virtues of high reliability and heating efficiency. The effect of factors, such as total air flow rate, the air inlet diameter of the combustion chamber, the ratio of the air flow rate of the combustion chamber to total air flow rate, on the performance is investigated experimentally. The experimental data shows that some parameters, such as the total air/fuel ratio, pressure in the second combustion chamber and specific impulse, decrease as the reduction of total air flow rate. Moreover, the hot gas flow rate increases as the reduction of the air inlet diameter or the increment of the air flow rate of the combustion chamber, which causes the reduction of the total air/fuel ratio and specific impulse.Considering the radiative heat transfer and the effect of the mass addition from the wall on the convective heat transfer coefficient, the fuel regression rate simulation model is established. On the basis of the above, the operation process simulation model of the solid fuel ramjet is established. The simulation program is coded, and is used to analyze the effect of different structure parameters and operating condition on the performance in detail. It is showed that the specific impulse should be the maximum at the design height, not merely considering enhancing the performance of the inlet. The flight velocity must be optimized in the missile overall design procedure. A proper design point can make the thrust stable during the flight. The solid fuel ramjet has good adaptability, for it can adjust thrust with the change of the flight height and velocity.On the base of the simulation analysis, five main parameters are selected as the optimize variables, and the design optimization model of the solid fuel ramjet is established. The optimize results show that the flight range increases 24.8 percent of the non-optimize results.更多还原