乙烯超声速燃烧的数值模拟研究

利用Fluent软件、ISAT算法与由CARM(Computer Assisted Reduction Method)简化而来的11组分、7步反应的乙烯简化机理对碳氢燃料/空气的超声速燃烧问题进行数值模拟.研究结果表明这种方法是可利用的.计算得到的压力数据与试验压力值可以比较.

Micro-shock waves generated inside a fluid jet impinging on plane wall

An Nd:glass laser pulse (18 ns, 1.38 J) is focused in a tiny area of about 100-mum diam under ambient conditions to produce micro-shock waves. The laser is focused above a planar surface with a typical standoff distance of about 4 mm, The laser energy is focused inside a supersonic circular jet of carbon dioxide gas produced by a nozzle with internal diameter of 2.9 mm and external diameter of 8 mm, Nominal value of the Mach number of the jet is around 2 with the corresponding pressure ratio of 7.5 (stagnation pressure/static pressure at the exit of the nozzle), The interaction process of the micro-shock wave generated inside the supersonic jet with the plane wall is investigated using double-pulse holographic interferometry. A strong surface vortex field with subsequent generation of a side jet propagating outward along the plane wail is observed. The interaction of the micro-shock wave with the cellular structure of the supersonic jet does not seem to influence the near surface features of the flowfield. The development of the coherent structures near the nozzle exit due to the upstream propagation of pressure waves seems to be affected by the outward propagating micro-shock wave. Mach reflection is observed when the micro-shock wave interacts with the plane wall at a standoff distance of 4 mm, The Mach stem is slightly deflected, indicating strong boundary-layer and viscous effects near the wall. The interaction process is also simulated numerically using an axisymmetric transient laminar Navier-Stokes solver. Qualitative agreement between experimental and numerical results is good.

超音速来流中侧向喷流干扰流场的数值模拟

通过求解三维可压缩N-S方程组，对尖锥／圆柱组合体模型在超音速绕流中的侧向喷流干扰流场进行了模拟，数值方法采用有限体积法，差分格式采用NND格式。分析了干扰流场的结构，研究了干扰效应对气动性能的影响，得到来流Ma。。=3．3和4．5时力放大因子和干扰力矩系数随攻角变化的规律，计算结果与实验一致。

Numerical Analyses of Discrete Gust Response for an Aircraft

Based on Navier-Stokes equations and structural and flight dynamic equations of motion, dynamic responses in vertical discrete gust flow perturbation are investigated for a supersonic transport model. A tightly coupled method was developed by subiterations between aerodynamic equations and dynamic equations of motion. First, under the assumption of rigid-body and single freedom of motion in the vertical plunging, the results of a direct-coupling method are compared with the results of quasi-steady model method. Then, gust responses for the one-minus-cosine gust profile arc analyzed with two freedoms of motion in plunging and pitching for the airplane configurations with and without the consideration of structural deformation.

超声速气流中含灰气体点源流动特性

采用Lagrange方法，研究了超声速气流中含灰气体点源的流动特性，求得了对称辆附近激波层内的流动参数。计算数值模拟结果揭示了大惯性颗粒在激波层内沿着相互交叉的振荡轨迹运动，颗粒分布形成了高、低密度层交错出现的“多层结构”，而且粒子子在轨迹包络线附近急剧聚集。

超声速大攻角旋成体迎风激波数值模拟

旋成弹体在大攻角超声速流动中其迎风面上有时会出现一种迎风激波.采用非定常雷诺平均的Navier-Stokes方程以及两方程kω-sst和代数B-L湍流模型成功地模拟了该现象,验证了该迎风激波是由于流场主旋涡导致超声速流动偏移造成的涡诱导激波的一部分的结论.

扩压段对高超声速推进风洞起动的影响

高超声速推进风洞是进行超燃冲压发动机模型地面模拟的重要试验设备.其中,扩压段的设计非常重要,它不是孤立的,而与主流系统和引射系统密切相关.通过对不同几何形状的扩压段在不同安装位置进行调试,研究在风洞起动过程中整个系统流动状态的演变规律,探索扩压段的优化设计.实验表明,扩压段应安装在距主喷管较近的位置,并具有与主喷管相匹配的入口面积和形状.扩压段的形状应设计成能使主气流通过一系列斜激波串减速的通道.扩压段应具有一定的长度以保证主气流减速到一定程度.

超声速气流中横向煤油射流的数值模拟

为了对超声速气流中液体横向射流进行数值模拟，采用Eulerian-Lagmngian方法描述气液两相流动现象，用随机轨道模型追踪液滴的运动历程，并考虑气流可压缩性、流场不均匀性及液滴变形对液滴运动的影响，开发了相应的计算程序。计算结果发现，液体射流与气流之间存在着强烈的相互作用，液滴在进入气流中不久就破碎成很小的子液滴，受煤油液雾的影响气流速度、温度急剧下降，同时在喷孔上游出现～道弓形激波。与液雾结构的纹影图像和液雾穿透的实验结果对比显示，数值计算结果基本合理。

直联式超燃实验台超声速燃气取样分析

在超燃冲压发动机实验中，燃烧室出口气体成份及分布是衡量燃烧情况的重要依据。笔者采用探针取样一色谱分析的方法，对于直联式超燃实验台不同工况下燃烧室出口气体进行了取样分析，总结了煤油燃烧比较完全、不完全以及基本未燃烧三种情况的典型气体分布规律。目前可测得的气体成份包括H2、O2、N2、CO、CO2、CH4和C2H4，进行成份分析与相应条件下燃烧室壁面静压分布比较，可进一步了解超声速燃烧的内部细节，为改进燃料掺混与燃烧提供参考数据。

超声速氧碘化学激光的性能分析

通过对超声速氧碘化学激光（COIL）的功率和效率计算，导出了适合于均匀和非均匀加宽效应同时起作用和非均匀加宽效应占优的情况，以及考虑频移效应的速度方程（RE）模型，得到了温度、压力、碘浓度以及频移对COIL的功率和效率的影响。

超燃燃烧室一维流场分析模型的研究

对公开发表的用于超声速燃烧流场分析的几种一维模型进行了研究，指出了其中存在的问题，研究结果表明：基于实验静压数据的一维模型，若不借助必要的流场测量数据或分析结果，或借助于经验性的处理方法，单靠一维假设，无法获得较为完整的一维流场分析结果。改进后的一维模型降低了数据处理过程中的不确定性，提高了对一般情况的适应能力。用编制的计算程序SSC-2对两组典型的超燃燃烧室壁面静压实验数据进行了演算，取得了燃烧室出口总压恢复系数的计算值与测量值基本一致的好结果。

煤油-空气预混气流超声速燃烧数值研究

对以高温燃气作为引导火焰的煤油．空气预混气流超声速燃烧进行了数值模拟，系统研究了预混气流的温度、压力、当量比，以及预混气流与高温燃气的压力匹配关系等多种重要因素对超声速燃烧的影响。结果表明：随着预混气流静温、静压的升高，着火点诱导的压缩波增强，最高燃烧温度升高，火焰传播角相应增大；预混气流的当量比为化学恰当比时，燃烧温度最高；与静压匹配的情况相比，静压不匹配情况下的火焰传播角增大，当预混气流的静压高于高温燃气的静压时，着火点前移，反之，着火点则后移；此外，在多种情况下，燃烧室下壁面边界层都出现了自燃现象。

超音速燃烧室氢氧基平面激光诱导荧光测量

用平面激光诱导荧光(PLIF)技术测量了氢/空气和煤油/空气超音速燃烧室氢氧基的荧光以及背景辐射光的图像.实验结果表明,PLIF是鉴别对燃烧性能起关键作用的燃料/空气混合过程的有效手段,发现在超音速燃烧室中PLIF氢氧基主要集中在凹腔区域,这有助于解释凹腔对超音速燃烧起稳定作用的机理.

Experimental Study on Hydrodynamic Behaviors of High-Speed Gas Jets in Still Water

The present paper describes experimental investigation on the flow pattern and hydrodynamic effect of underwater gas jets from supersonic and sonic nozzles operated in correct- and imperfect expansion conditions. The flow visualizations show that jetting is the flow regime for the submerged gas injection at a high speed in the parameter range under consideration. The obtained results indicate that high-speed gas jets in still water induce large pressure pulsations upstream of the nozzle exit and the presence of shock-cell structure in the over- and under-expanded jets leads to an increase in the intensity of the jet-induced hydrodynamic pressure.