Development Status and Prospects of Solid Rocket Motor Technology for Large Launch Vehicles

In this study,taking China's Smart Dragon 3 solid launch vehicle,which made its first successful offshore launch on December 9,2022,as an example,we focus on the technical characteristics and key technologies of various solid motors used for the launch vehicle.The current technological development status is introduced,and the key technologies needed for large solid motors are summarized.For comparison,we also list and analyze the technical characteristics of world-class P80 and P120C solid motors used in ESA's Vega series of launch vehicles.On this basis,the development trends of large solid motors based on the requirements for launch vehicles is proposed,providing a reference for the development of large solid motor technology for future launch vehicles in China.

Study on Instable Combustion of Solid Rocket Motor with Finocyl Grain

The instable combustion or oscillation combustion which occurs in three high capacity solid rocket motors using high energy composite propellant with finocyl grain is studied. The reasons of the acoustic combustion instability are also discussed. Three engineering methods that can eliminate combustion instability are proposed and discussed. The study shows that the combustion instability mainly depends on the propellant grain shape and nozzle structure. Some measures to reduce the acoustic energy and mass generation rate of combustion gas can be adopted. The test results indicate that the modified rocket motors can significantly eliminate the instable combustion and improve the motor internal ballistic performance.

Research on the Initial Ignition of the Underwater Launching Solid Rocket Motor

The aim of this investigation is to research the initial ignition of the underwater-launching solid rocket motor.The MIXTURE multiple-phase model was set to simulate the initial ignition.The water vaporization was researched and the energy transfer was added to the energy equations.The flow field and the vaporization were calculated coupled.The initial ignition process of the underwater solid rocket motor is obtained and the vaporization influence to the underwater launching is analyzed.The ＂neck＂,＂inverted jet＂ and ＂eruption＂ phenomenon of the bubble are observed.The bubble increases more rapidly because the steam mass added to the fuel.The temperature is lower considering the vaporization because the steam enthalpy is lower than the fuel enthalpy and the flow field of the initial ignition of the underwater-launching solid rocket motor is accordant well to the reference.

The properties of Sn-Zn-Al-La fusible alloy for mitigation devices of solid propellant rocket motors

The Al and La elements are added to the Sn9Zn alloy to obtain the fusible alloy for the mitigation devices of solid propellant rocket motors. Differential scanning calorimetry(DSC), metallographic analysis,scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS), tensile testing and fracture analysis were used to study the effect of Al and La elements on the microstructure, melting characteristics, and mechanical properties of the Sn9Zn alloy. Whether the fusible diaphragm can effectively relieve pressure was investigated by the hydrostatic pressure at high-temperature test. Experimental results show that the melting point of the Sn9Zn-0.8Al0·2La and Sn9Zn-3Al0·2La fusible alloys can meet the predetermined working temperature of ventilation. The mechanical properties of those are more than 35% higher than that of the Sn9Zn alloy at-50°C-70°C, and the mechanical strength is reduced by 80% at 175°C. It is proven by the hydrostatic pressure at high-temperature test that the fusible diaphragm can relieve pressure effectively and can be used for the design of the mitigation devices of solid propellant rocket motors.

Influence of Solid Rocket Motor Slag on the Space Debris Environment

The resulting slag particles from solid rocket motor( SRM) firings are an important component of space debris environment. Slag sizes as large as 1 cm have been witnessed in ground tests,and comparable sizes have been also estimated via observations of sub-orbital tail-off events. We achieve slag initial data based on MASTER slag model and SRM historical launch data,and propagate slag long-term orbital evolution taking into account the zonal harmonics J2,atmospheric drag,solar radiation pressure and luni-solar attraction to discuss the slag size distribution and orbital characteristics. Finally,future slag debris environment is evaluated based on two different launch rate assumptions. The result shows that current launch frequency will make the slag population sustain growth and the population will not decrease at once even if there are no more launches in the future.

Laminar and Turbulent Characteristics of the Acoustic/Fluid Dynamics Interactions in a Slender Simulated Solid Rocket Motor Chamber

In this paper,analytical,computational,and experimental studies are integrated to examine unsteady acoustic/vorticity transport phenomena in a solid rocket motor chamber with end-wall disturbance and side-wall injection.Acoustic-fluid dynamic interactions across the chamber may generate intense unsteady vorticity with associated shear stresses.These stresses may cause scouring and,in turn,enhance the heat rate and erosional burning of solid propellant in a real rocket chamber.In this modelling,the unsteady propellant gasification is mimicked by steady-state flow disturbed by end-wall oscillations.The analytical approach is formulated using an asymptotic technique to reduce the full governing equations.The equations that arise from the analysis possess wave properties are solved in an initial-boundary value sense.The numerical study is performed by solving the parabolized Navier–Stokes equations for the DNS simulation and unsteady Reynolds-averaged Navier–Stokes equations along with the energy equation using the control volume approach based on a staggered grid system with the turbulence modelling.The v2-f turbulence model has been implemented.The results show that an unexpectedly large amplitude of unsteady vorticity is generated at the injection side-wall of the chamber and is then penetrated downstream by the bulk motion of the internal flow.These stresses may cause a scouring effect and large transient heat transfer on the combustion surface.A comparison between the analytical,computational,and experimental results is performed.

On the Transient Numerical Simulation of Solid Rocket Motor by Coupling Quasi One⁃Dimension Internal Flow with Three⁃Dimension Propellant Grain Burnback

The quasi one⁃dimension compressible flowfield coupled to the three⁃dimension propellant grain regression solved by the level⁃set method was used to simulate the transient internal ballistics of solid rocket motor.One⁃dimension flowfield instead of three⁃dimension can save computational cost on the premise of calculation accuracy because the radial and azimuthal variations parameters have little contribution to the internal flowfield.The grain regression in real⁃time could provide accurate geometrical information for simulation.A combination of flowfluid solver and grain regression can reappear in a relatively real internal ballistic flowfield,so it is good for further studying the instability of solid rocket motor.For level⁃set equations,the total variation⁃diminishing second⁃order Runge⁃Kutta method for temporal derivatives and a fifth⁃order weighted⁃essentially⁃non⁃oscillatory scheme for spatial derivatives were used.The total variation⁃diminishing MacCormack method was used to discrete the Euler equations in flowfield solver.Two modules of this code were tested in this study:one is the burning rate module and the other is the nozzle erosion module.Results show that the burning rate influenced the solid rocket motor efficiency,and the velocity profile in the chamber was affected by the nozzle shape,and the nozzle erosion could influence the head⁃end pressure spike.

Research on Instantaneous Thrust Measurement for Attitude-control Solid Rocket Motor

In order to measure the instantaneous thrust of a certain attitude-control solid rocket motor, based on the analysis of the measurement principles, the difference between the instantaneous thrust and steady thrust measurements is pointed out. According to the measurement characteristics, a dynamic digital filter compensation method is presented. Combined the identification-modeling, dynamic compensation and simulation, the system's dynamic mathematic model is established. And then, a compensation digital filter is also designed. Thus, the dynamic response of the system is improved and the instantaneous thrust measurement can be implemented. The measurement results for the rocket motor show that the digital filter compensation is effective in the instantaneous thrust measurement.

Measurement of alumina film induced ablation of internal insulator in solid rocket environment

This study investigates the ablation of internal insulation induced by the deposition of an alumina film with different lateral film speeds.A sub-scale test solid rocket motor(SRM)was designed in an impinging jet configuration to form an alumina film on the sample and to encourage the lateral movement of the film by a high-speed wall jet.Fifteen static fire tests of the test SRM were conducted with six different jet velocities(V_(jet)=100 m/s,150 m/s,200 m/s,268 m/s,330 m/s,and 450 m/s)that indirectly affected the velocity of the wall jet and the deposition rate of alumina droplets.The ablation velocity was deduced from the difference in the sample thickness after a test using a coordinate measuring machine.The droplet deposition mass flux and wall jet velocity were obtained via two-phase flow simulation with the same jet velocity and effective pressure.As a result,the characteristics of alumina-induced ablation and the changes in ablation with jet velocities were obtained.The area within0.8×jet diameter was focused upon,where the ratio of ablation velocity to incoming alumina mass was constant for each jet velocity,and showed a similarity in jet structure.When the ablation velocity was increased from 2.05 to 9.98 mm/s with increasing jet velocity,the ratio of the ablation velocity and alumina mass flux decreased from 1.07×10^(-4)to 0.49×10^(-4)m^(3)/kg as Al_(2)O_(3)-C reactions became less efficient with a reduced residence time of the film.Because the decrease in residence time by the wall jet is more pronounced for slow reactions involved in Al_(2)O_(3)-C reactions,fast reactions in Al_(2)O_(3)-C reactions are less affected and result in a convergence of the volumetric rate of ablation per unit mass of alumina.

China's Civil Solid Rocket Motors

China develops solid fuelrocket technology completely de-pending on its own strength.Since the late 1950s,variouskinds of solid rocket engines de-veloped by the 4th Academy ofChina Aerospace Corporation(CASC)have been used intomany positioning and recoveringtests of various satellites and over100 flight tests of various missileswith a 100％ successful rate.InOctober,1982,especially,Chinasuccessfully launched a solid fuelrocket from a submarine underwater,which reflected China’shigh level in this field.China’scivilian solid rocket engines are asfollows:

Study on the Multi-Component Test Technology of Solid Rocket Motors

This paper presents a calculation method, and composition of a five-component force test device, to resolve the requirement for solid rocket motor multi-component force test. It compares the difference between two classical algorithms, and summarizes the structure and practical usage of the solid rocket motor multi-component force using soft connection structure measurement. The decoupling method of test data is described, and a reasonable research method for solid rocket motor multi-component force is also given in this paper.

Development of Solid Rocket Motor for Manned Launch Vehicle Escape System

The solid rocket motors for the escape system of China’s LM-2 F manned launch vehicle are described,the key technologies and technical innovations utilized are summarized.The technical features and development of foreign manned launch abort systems are also presented.The development trends of the solid rocket motor for future Chinese manned launch vehicle escape systems are proposed,which can provide a reference for the future development of manned launch vehicle escape systems.

Solid Rocket Motors for Launch Escape Tower Provide Safety to Astronauts

Compared with other ordinary launch vehicles, the LM-2F launch vehicle has two special systems, the fault detection processing system and launch escape system, because it is used for manned spaceflight missions. During the 10 flight missions carried out by LM-2F, only the

长时间工作固体火箭发动机长尾喷管外绝热装置设计

固体火箭发动机长尾喷管周围一般安装有电子仪器,故而对喷管壳体表面温度有严格的限制。对于某长时间工作的发动机,为满足喷管壳体表面温度要求,同时降低消极质量,设计了一种新型双腔外绝热装置,以实现在较小的消极质量下具有较好的绝热性能。对该绝热装置进行了内流场及传热计算分析,而后进行了绝热结构优化及试验验证。结果表明:该双腔外绝热装置可以将长时间工作固体火箭发动机长尾喷管外壁温度从483℃降低至103℃,降低约78.7%;而采用同等材料同等质量的常规外防护装置只能从483℃降低至227℃,降低约53.0%;而要达到相同的防护效果,同等材料常规外防护装置的质量将增加约160%。双腔外绝热装置中段及尾端处温度随时间变化趋势与实测结果吻合较好,有望应用于其他长时间工作发动机。

基于神经网络的零射程线闭路制导方法

对于固体发动机飞行器,在动力飞行段一般采用能量匹配闭路制导或者倾角约束的闭路制导方法,这种闭路制导方法的控制精度较高,但其精度受到发动机性能偏差的影响较大,为了减小发动机性能偏差对制导精度的影响,提出了基于神经网络的零射程线闭路制导方法。首先,建立了飞行器动力飞行段运动模型,对零射程线闭路制导进行了分析推导;其次,设计了多输入神经网络算法,确定了输入输出参数,对剩余能量、待增速度以及趋零射程线角度进行训练,将神经网络训练结果与零射程线闭路制导相结合,使得在不同的发动机偏差情况下,反馈不同的趋零射程线角度;最后,通过选择不同的偏差状态进行仿真验证,仿真结果表明该方法能有效地减小发动机偏差对制导精度的影响,具有较强的抗偏差能力,制导精度高。

节流式燃/氧分离组合固体发动机推力性能调节数值研究

节流式燃/氧分离组合固体发动机将燃烧室分为富燃燃烧室和富氧燃烧室,采用富燃固体推进剂和富氧固体推进剂串联装填的形式,在两个燃烧室中间增加节流阀,通过调节节流阀开度实现推力调节。利用商业软件对节流式燃/氧分离组合固体发动机在节流阀流道半径不同时的工作状态进行模拟,研究节流式燃/氧分离组合固体发动机的工作特性,获得节流式燃/氧分离组合固体发动机燃气流动和掺混特征,揭示节流式燃/氧分离组合固体发动机推力调节机理以及节流阀流道半径对节流式燃/氧分离组合固体发动机燃烧效率的影响规律。研究发现:节流阀流道开度(即节流阀流道半径R)减小可增大发动机推力;随着节流阀开度的减小,节流阀出口燃气马赫数随之增大,而发动机燃烧效率却出现先增大后减小的规律,当节流阀出口燃气流动达到临界状态时发动机燃烧效率出现最大值。

壁面开孔方式对可渗透喷管推力性能影响数值研究

为降低传统大扩张比喷管在低空飞行时喷管内燃气过膨胀带来的推力损失,提出一种具有自适应高度补偿功能的可渗透壁喷管。对采用不同壁面开孔方式的可渗透喷管进行数值模拟,对比并分析喷管的全弹道推力性能。计算结果显示,可渗透喷管在低空下的推力补偿效果明显,比冲增益最高达10%,在高空下的推力损失低至1%,高度平均比冲增益最高达1.5%。在孔隙率、壁面开孔形状相同的情况下,壁面开孔尺度越小可渗透喷管的推力性能越好,但总体上不同壁面开孔尺度的可渗透喷管的全弹道性能差异为0.6%。产生性能差异的主要原因是相同孔隙率的情况下,低空通过小尺度孔进入喷管的气流更均匀,对可渗透段内壁面压强的提升以及分离激波的削弱效果更好,因此带来的低空推力补偿效果更好。在孔隙率、壁面开孔尺度相同的情况下,采用圆柱孔的可渗透喷管的推力性能要优于圆锥孔的可渗透喷管。综合性能最好的圆柱孔可渗透喷管与综合性能较差的渐缩型圆锥孔可渗透喷管的全弹道性能相差约3.3%。

节流式燃/氧分离组合固体火箭发动机动态工作过程数值研究

利用商业软件ANSYS Fluent对节流式燃/氧分离组合固体火箭发动机动态工作过程进行数值研究,揭示该发动机基本动态工作过程以及节流阀作动速度的影响。结果表明,节流阀作动会导致发动机富氧燃烧室压强、节流阀出口质量流量以及发动机推力出现负调现象;节流阀作动速度差异不影响发动机调节后的稳定工作状态;随着节流阀作动速度增大,发动机达到稳定工作状态所需时间逐渐缩短,实现性能调控的响应速度增快,但发动机各参数负调量也随之增大,从而增加了发动机发生振动的风险。

后摆心潜入式喷管柔性接头力学特性数值仿真

针对后摆心潜入式喷管柔性接头在燃气压力与摆动联合载荷下,弹性件与增强件的力学特性计算问题,建立了对称刚体-柔性体结合的几何模型;采用了有限元方法,获取了柔性接头在燃气压力、摆动载荷及联合载荷下应力、弹性比力矩分布规律。研究表明:随着燃气压力增大,弹性比力矩降低;随摆角增大,弹性比力矩增大。文中的数值仿真方法,可以应用于柔性接头力学特性的计算,为柔性接头强度的安全性评估提供指导。