固体火箭发动机冲击响应分析中改进的Wilson－θ法

在Ｗｉｌｓｏｎ－θ法基础上引入参数γ，提出了修正的振动平衡方程和初始条件表达式。研究了新方法的稳定性和γ系数的取值范围，并以某些导弹的发动机壳体为算例和实验对象，验证了新方法的正确性和在抑制超调现象方面的有效性。     

Multi-disciplinary design optimization with fuzzy uncertainties and its application in hybrid rocket motor powered launch vehicle

In this paper, an Uncertainty-based Multi-disciplinary Design Optimization (UMDO) method combining with fuzzy theory and Multi-Discipline Feasible (MDF) method is developed for the conceptual design of a Hybrid Rocket Motor (HRM) powered Launch Vehicle (LV). In the method proposed, membership functions are used to represent the uncertain factors, the fuzzy statistical experiment is introduced to analyze the propagation of uncertainties, and means, standard deviations and credibility measures are used to delineate uncertain responses. A geometric programming problem is solved to verify the feasibility of the Fuzzy-based Multi-Discipline Feasible (F-MDF) method. A multi-disciplinary analysis of a three-stage HRM powered LV involving the disciplines of propulsion, structure, aerodynamics and trajectory is implemented, and the mathematical models corresponding to the F-MDF method and the MDF method are established. A two-phase optimization method is proposed for multi-disciplinary design optimization of the LV, including the orbital capacity optimization phase based on the Ziolkowski formula, and the scheme trajectory verification phase based on the 3-degree-of-freedom point trajectory simulation. The correlation coefficients and the quadratic Response Surface Method (RSM) based on Latin Hypercube Sampling (LHS) are adopted for sensitive analysis of uncertain factors, and the Multi-Island Genetic Algorithm (MIGA) is adopted as the optimization algorithm. The results show that the F-MDF method is applicable in LV conceptual design, and the design with the F-MDF method is more reliable and robust than that with the MDF method.     

用加速度计的积分遥测量计算弹道参数及轨道要素

文章提供利用运载火箭特征点(关机点,入轨点等)的有关加速度计的积分遥测量计算该点的弹道参数和轨道要素的计算方法。     

Aerospike nozzle contour design and its performance validation

A simplified design and optimization method of aerospike nozzle contour and the results of tests and numerical simulation of aerospike nozzles are presented. The primary nozzle contour is approximated by two circular arcs and a parabola; the plug contour is approximated by a parabola and a third-order polynomial. The maximum total impulse from sea level to design altitude is adopted as objective to optimize the aerospike nozzle contour. Experimental studies were performed on a 6-cell tile-shaped aerospike nozzle, a 1-cell linear aerospike nozzle and a 3-cell aerospike nozzle with round-to-rectangle (RTR) primary nozzles designed by method proposed in present paper. Three aerospike nozzles achieved good altitude compensation capacities in the tests and still had better performance at off-design altitudes compared with that of the bell-shaped nozzle. In cold-flow tests, 6-cell tile-shaped aerospike nozzle and 1-cell linear aerospike nozzle obtained high thrust efficiency at design altitude. Employing gas H₂/gas O₂ (GH₂/GO₂) as propellants, hot-firing tests were carried out on a 3-cell aerospike nozzle engine with RTR primary nozzles. The performance was obtained under two nozzle pressure ratios (NPR) lower than design altitude. Efficiency reached 92.0–93.5% and 95.0–96.0%, respectively. Pressure distribution along plug ramp was measured and the effects of variation in the amount of base bleed on performance were also examined in the tests.     

RBCC引射/亚燃模态过渡工作过程数值模拟

针对模态过渡过程中的瞬变特性,开展了引射/亚燃模态过渡工作过程中的RBCC进气道/燃烧室一体化数值模拟,计算比较了四种不同的模态过渡方案,分析了模态过渡工作过程中流动、燃烧模式和进气道状态的瞬变过程,研究结果表明:(1)推力产生较大波动的主要原因是燃烧室内燃烧/流动参数匹配性差和在流动方向上燃烧放热间断引起的;(2)主火箭保留的燃气在模态过渡过程中起到了火焰稳定和自持燃烧的作用,保留合理流量的燃气不仅可以缩短模态过渡时间,而且可以提高发动机的比冲;(3)提出了通过调节燃料喷注策略和主火箭节流方式实现模态平稳过渡的方案,并对该方案进行了数值验证,可望为进一步的实验研究提供了燃烧控制方法。     

某型发动机一级风扇机匣包容性数值仿真

为研究航空发动机机匣/叶片包容性过程机理,以某型发动机一级风扇机匣/叶片为对象,建立了三种有限元模型,研究了最高工作转速下的非包容过程,分析了完整叶片等对非包容过程的影响.结果表明:该型发动机一级风扇机匣是非包容的;机匣初始裂纹的主要失效模式为双向拉伸应力下的拉伸失效,随后裂纹扩展产生大范围的撕裂;断叶受较复杂载荷的作用,最终在凸肩处断裂成二部分;断叶与机匣的撞击过程可分成三个阶段,第一次撞击为叶尖与机匣的轻微撞击,第二次撞击作用力最大,而第三次撞击受断叶后侧完整叶片的作用非常明显.受完整叶片的撞击,断叶动能有明显的增加.      

短连杆飞行载荷实测技术

飞行载荷实测是新机定型的一个必要环节,飞机操纵面铰链力矩测量是飞机飞行载荷测量的一部分。结合实际工程提出一种飞机操纵面短连杆飞行载荷实测新技术,并将其应用于某型飞机定型试飞中。进行短连杆校准试验,发现应变电桥受拉、压载荷时响应系数差异大于45%,因此,短连杆结构件在飞行载荷测量时需完成拉、压向两种校准试验工况。     

转子-支承-机匣系统碰摩试验及特征提取

针对航空发动机转子系统的结构特征和转静件碰摩的动力学特征,建立了转子-支承-机匣系统碰摩模拟试验器.对叶片与机匣间轻微碰摩和严重碰摩两种工况下转子和机匣振动响应进行了试验测量,并基于连续小波变换和连续小波包能量的时-频分析方法分别对转子和机匣的振动信号进行了特征提取.结果表明机匣响应信号同时包含高频冲击信号和低频摩擦信号,轻微碰摩时以碰撞冲击效果为主,机匣响应主要为高频冲击信号;严重碰摩时摩擦效应增强,可为碰摩故障诊断和识别提供方法和依据.      

冲压燃烧室V型燃料喷射结构的分离涡模拟

液态燃料的喷注方式会显著影响火箭基组合循环(RBCC)发动机燃烧室的火焰组织与燃烧效率。通过湍流流动的分离涡模拟,数值计算了RBCC燃烧室液态煤油喷雾燃烧的三维两相流动,并提出了采用V型阵列结构的喷孔空间组合形式,研究结果表明,V型喷孔排列结构,消除了侧壁液态燃料蒸发对值班火焰所带来的消极影响,并通过调整不同喷孔流量,强化了中间喷孔射流形成的值班火焰,相对于直线喷排,可拓宽火焰稳定阈值,提高燃料的蒸发效率与燃烧效率。     

外压载荷分布形式对固体火箭发动机结构稳定性的影响

应用有限元软件开展了燃烧室全筒段均压、全筒段分布式外压、局部均压三种状态外压稳定性分析,得到了三种状态的失稳载荷和屈曲波形,为不同载荷分布的外压试验方案的制定提供理论基础.分析表明:三种状态中全筒段均压状态的失稳载荷最低,三种状态的屈曲波发生部位也不一样.全筒段均压状态的外压试验结果不能代表分布式或局部外压下的承载能力...