时空守恒CE/SE数值方法在凹槽燃烧流动中的应用研究

应用时空守恒元和解元CE/SE方法,发展了求解化学反应流场的三维并行计算程序。为验证程序,对超声速冲压喷射燃烧室模型进行了计算,计算结果与实测数据以及相关文献的计算结果吻合较好,验证了本文的处理方法和程序的正确性。采用H2和O2的8组分34基元化学反应模型,对不同长深比的凹槽燃烧流动进行了数值模拟,分析了凹槽增强混合对稳定火焰的作用。计算结果表明,CE/SE方法具有模拟凹槽超声速燃烧流动的能力,数值模拟的结果有助于认识凹槽的火焰稳定机理。     

材料参数及静水压力对孔洞敏感材料超塑胀形影响的数值分析

本文将变形损伤效应引入到基于超塑成形的微观机理推导出的超塑性本构方程中，并将本构方程应用于刚塑性有限元模拟程序，分析了板料超塑胀形过程，研究了应变速率敏感性、孔洞长大以及叠加静水压力对孔洞敏感材料超塑胀形极限的影响，对模拟结果与实验结果进行了比较。     

带凹腔火焰稳定器的固体火箭超燃冲压发动机燃烧室试验研究

以含硼贫氧固体推进剂为燃料,对带凹腔火焰稳定器的固体火箭超燃冲压发动机燃烧室构型首次开展了地面直连试验研究.试验模拟了23km,5.5Ma的飞行工况,通过测量压强、推力和流量等参数,得出了燃烧室性能.试验结果表明:一次富燃燃气在燃气发生器喉部沉积导致燃气流量持续提高,试验过程中当量比由0.44逐渐增加至0.54;本文所...     

基于Driscoll凹腔稳焰模型的超声速燃烧火焰稳定尺度效应研究

为了研究超声速燃烧室尺度放大后,保持火焰稳定边界相对于基准燃烧室不变,凹腔火焰稳定器几何参数应遵循何种放大准则的问题,基于已有的Driscoll凹腔稳焰数学模型,采用典型的单凹腔矩形截面燃烧室作为基准燃烧室,分别计算基准燃烧室在贫燃和富燃状态时的火焰稳定准则数DaNP,再按照燃烧室尺度放大定义写出尺度放大燃烧室的稳焰准则数表达式Da''NP,将稳焰边界不变作为约束条件,构建尺度放大准则方程式DaNP= Da''NP,求解准则方程式获得凹腔几何参数放大准则表达式,绘制准则特性曲线,分析归纳近似准则,并通过数值计算方法初步验证准则的有效性。采用Driscoll凹腔稳焰模型的尺度效应分析结果表明,燃烧室放大一定倍数n后,无法通过调整凹腔长度和深度放大倍数k1和k2使得贫燃熄火边界保持不变;但是,可以通过调整参数k1和k2使得富燃熄火边界保持不变,此时凹腔几何参数遵循的放大准则近似为 k1≈k2≈n1/4。     

Self-sustained oscillation for compressible cylindrical cavity flows

The presence of a cavity changes the mean and fluctuating pressure distributions. Similarities are observed between a cylindrical cavity and a rectangular cavity for a compressible flow.The type of cavity flow field depends on the diameter-to-depth ratio and the length-to-depth ratio.The feedback loop is responsible for the generation of discrete acoustic tones. In this study, the selfsustained oscillation for a compressible cylindrical cavity flow was investigated experimentally. For open-type cavities, the power spectra show that the strength of resonance depends on the diameterto-depth ratio(4.43–43.0) and the incoming boundary layer thickness-to-depth ratio(0.72–7.0). The effective streamwise length is used as the characteristic length to estimate the Strouhal number. At higher modes, there is a large deviation from Rossiter's formula for rectangular cavities. The gradient-based searching method was used to evaluate the values of the empirical parameters. Less phase lag and a lower convection velocity are observed.     

Effect of injection scheme on asymmetric phenomenon in rectangular and circular scramjets

The asymmetric separation has a crucial effect on the performance of the scramjet. In this study, the asymmetric separation and combustion in both rectangular and circular scramjets are investigated numerically, and the effect of injection scheme is analyzed. The characteristics of the flow field are analyzed based on sufficient code verification. In the rectangular scramjet, the separation tends to occur in the corner due to the corner boundary-layer effect. The separation is asymmetric and only two corners have serious separation. The fuel penetration depth in the separation zone increases and the combustion is intensified. When the injection scheme is uniform, both the combustion and separation become weak. In the circular scramjet, the separation and combustion are basically axisymmetric in the scramjet with one-row injection scheme. The asymmetric combustion becomes obvious in cases with multi-row injection scheme. When the injection orifices distribute intensively on the top and bottom sides, the strongest and weakest separations occur near these two sides respectively. When the distribution of orifices becomes uniform, the direction of separation cannot be predicted. For multi-row cases, the nonuniform injection scheme could result in violent combustion and asymmetric flow structures compared with the uniform injection scheme.     

MCGA-assisted ignition process and flame propagation of a scramjet at Mach 2.0

The ignition process and flame propagation with ethylene fuel in cavity-stabilized scramjet by a Multi-Channel Gliding Arc(MCGA) at Mach 2.0 were investigated. Effects of equivalence ratios on the MCGA-assisted ignition process and flame propagation of the scramjet were recorded by two high-speed cameras from different view angles. The discharge characteristics of MCGA are also collected synchronously with the high-speed cameras. The distributions of temperature, velocity, and equivalence ratios...     

Mixing and combustion characteristics in a scramjet combustor with different distances between cavity and backward-facing step

The mixing and combustion characteristics in a cavity flameholding combustor under inlet Mach number 2.92 are numerically investigated with ethylene injection. Dimensionless distance is defined as the ratio of the actual distance to the height of the combustor entrance. The cavity shear-layer mode, the lifted cavity shear-layer mode, and jet wake mode with upstream separation are observed respectively with dimensionless distance equals to 1.5, 4.5, and 7.5. In both non-reacting and reacting flow...     

新型微光机电系统惯性测量技术研究进展

微惯性测量单元(MIMU)是惯性导航系统(INS)的核心组件，亦是构建微定位导航授时（μ-PNT）系统的重要组成部分。当前成熟的微惯性测量单元主要基于微机电系统（MEMS）实现，其性能逐渐难以满足新型无人驾驶车、无人飞行器以及制导弹药、航空航天器等军民用领域对高精确惯性导航的需求。近年来,各种新型微惯性测量技术相继被提出，以期望突破微惯性测量单元的性能与尺寸、质量、功耗（SWaP）之间相互制约的关键技术难题。系统总结了近年来国内外在常规MEMS惯性测量技术以及新型微光机电系统（MOEMS）惯性测量、微腔光力惯性测量、量子精密测量等几类新型惯性测量技术方面的研究进展，展望了未来新型高精度惯性测量技术的发展趋势，并提出了一种基于腔光力系统的量子增强型惯性测量技术构想。     

空间三轴激光陀螺双通道调腔技术研究

反射镜的复用减小了空间三轴激光陀螺的体积,但也增加了其调腔难度。传统调腔技术沿用单轴激光陀螺的调腔模式对空间三轴激光陀螺进行调腔,步骤复杂且耗时较长。针对此问题,结合空间三轴激光陀螺的结构特点,分析了传统调腔技术效果欠佳的原因,并提出了一种双通道调腔技术。最后搭建了实验样机,利用双通道调腔技术对空间三轴激光陀螺进行调腔,并与传统调腔技术进行了对比。结果表明,在相同失准误差的要求下,利用双通道调腔技术可使空间三轴激光陀螺的调腔时间减少约70%。