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自燃推进剂火箭发动机燃烧不稳定性研究 总被引:4,自引:1,他引:3
发展了自燃推进剂(MMH/NTO)火箭发动机燃烧不稳定性的综合分析模型。以蒸发作为燃烧速率控制过程,研究了燃烧不稳定性的机理,提出了轴向声腔模型并对其抑制不稳定燃烧的特性进行了数值模拟研究,得到了声槽特性频率驿燃烧不稳定性的影响规律,描绘出声腔影响燃烧不稳定性的具体场景,数值模拟结果与理论分析及试车结果是相符的,对轴向声槽的分析设计将具有广泛的指导意义。 相似文献
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Numerical evaluation of acoustic characteristics and their damping of a thrust chamber using a constant-volume bomb model 总被引:1,自引:0,他引:1
In order to numerically evaluate the acoustic characteristics of liquid rocket engine thrust chambers by means of a computational fluid dynamics method, a mathematical model of an artificial constant-volume bomb is proposed in this paper. A localized pressure pulse with a very high amplitude can be imposed on specified regions in a combustion chamber, the numerical procedure of which is described. Pressure oscillations actuated by the released constant-volume bomb can then be analyzed via Fast Fourier Transformation (FFT), and their modes can be identified according to the theoretical acoustic eigenfrequencies of the thrust chamber. The damping performances of the corresponding acoustic modes are evaluated by the half-power bandwidth method. The predicted acoustic characteristics and their damping for a special engine combustor agree well with the experimental data, validating the mathematical model and its numerical procedures. A small-thrust liquid rocket engine chamber is then analyzed by the present model. The First Longitudinal (1L) acoustic mode can be excited easily and is hard to be damped. The axial position of the central constant-volume bomb has little influence on the amplitude and damping capacity of the First Radial (1R) and 1L acoustic modes. Tangential acoustic modes can only be triggered by an off-centered constant-volume bomb, among which the First Tangential (1T) mode is the strongest and regarded as the most harmful one. The amplitude of the 1L acoustic mode is smaller, but its damping factor is larger, as a constant-volume bomb is imposed approaching the injector face. These results are contributed to evaluate the acoustic characteristics and their damping of the combustion chamber. 相似文献
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对液体火箭发动机气液同轴式喷嘴声学特性进行了深入的实验研究,确定了不同缩进比的气液同轴式喷嘴工作时发生啸叫的参数范围、啸叫的频率和声压级分布,并考察了啸叫对喷嘴雾化特性的影响。结果表明;气液同轴式喷嘴的啸叫区间与喷嘴的结构尺寸有密切的关系.较大的喷嘴缩进比对啸叫有明显的抑制作用,啸叫的主要成分是高频噪声,这种喷嘴啸叫可能成为诱发发动机高频不稳定燃烧的重要因素。另外,实验还发现,在较低的气体喷注压降下,啸叫对喷嘴雾化有一定的强化作用。 相似文献
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《中国航空学报》2021,34(2):432-440
Reusable rocket engines are the core components of reusable launch vehicles, and have thus become a major focus of aerospace engineering research in recent years. In practice, subsystem design is based on the overall index allocation of an engine; therefore, a multidisciplinary optimization approach is necessary. In this study, design of a reusable methane/liquid oxygen (LOX/CH4) rocket engine with a gas generator cycle was investigated using multidisciplinary optimization. Two parameters were chosen as design variables: pressure and fuel mix ratio of the main combustion chamber. Optimization objectives were specific impulse, structural mass, and life cycle cost of the reusable rocket engine, and constraints were assigned to each discipline according to rocket design requirements. Then, an optimization model was developed, and optimal design parameters were acquired for the LOX/CH4 rocket engine. The proposed method is effective for designing the index allocation of reusable rocket engines and takes into account the multidisciplinary nature of complex systems. 相似文献
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早期在对液体推进剂火箭发动机方案进行评价与选择时,仅以发动机本身的指标(如比冲、推重比等)作为方案比较的标准。这样没有考虑发动机子系统与运载器总系统的相互联系,得不到合理的评价结果。液体推进剂火箭发动机是航天运载器的一个子系统,采用运载器的性能指标评价发动机方案才能得到比较客观的结果。 本文推导了运载器的评价指标,给出了运载器的线性化质量方程,阐述了运载器设计参数的简化确定方法,由此提出了一个采用运载器评价发动机方案的方法。最后应用提出的方法对五个发动机方案进行了评价。 相似文献
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气喷嘴和声腔对燃烧室声学特性的影响 总被引:2,自引:0,他引:2
为了掌握气喷嘴和声腔对燃烧室声学特性的影响规律以及解释声学实验中出现的切向频率分化现象的内在机理,采用声学有限元方法(FEM)并在单喷嘴声学模拟实验验证的基础上,从固有频率和声压分布角度分析了气喷嘴长度、声腔长度和节流嘴直径对燃烧室声学特性的影响规律,利用声压分布成功地解释了实验中出现的频率分化现象。结果表明:当燃烧室某阶切向振型频率与喷嘴1阶纵向振型频率相等时,喷嘴由于共振将切向振型声压幅值极值点附近的能量转移到喷嘴中,改变了燃烧室原切向振型的声压分布,因此在声学实验中产生切向频率分化现象;气喷嘴长度与节流嘴直径之间存在着耦合关系,在液氧煤油补燃发动机喷嘴设计阶段可进行组合参数匹配优化。 相似文献
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本文通过对某单室双推力发动机推力测试技术的探讨,提出了解决单室双推力固体火箭发动机推力测试技术的改进方法。它对其它发动机也是通用的。 相似文献