摘要: Outcomes of experimental researches of the low-pressure adiabatic flow of the boiling liquid through two-dimensional Laval nozzles in a vacuum atmosphere were adduced. Requirements of critical conditions of flow were determined. Structural forms of a stream were investigated and their connection with crisis of flow was shown. It was established periodic non-stationary macrostructures of a stream which was stipulated by the rotational gear of origin of a vapor phase.
摘要: Different turbulence closures were used to predict the flow interaction between the wakes created by compressor outlet guide vanes (OGVs) and a downstream annular pre-diffuser. Two statistical turbulence models were tested based on the classical Reynolds-averaged Navier-Stokes (RANS) approach. Both high- Re and low- Re (Launder-Sharma) versions of the k-ε model were applied to a selected test problem for OGV wake/diffuser flows. The test problem was specifically chosen because experimentally determined inlet conditions and both profile and performance data were available to validate predictions. A preliminary study was also reported of the more advanced large eddy simulation (LES) approach. The LES sub-grid-scale (SGS) model was the basic Smagorinsky eddy viscosity assumption, with a Van-Driest damping function for improved capture of near-wall viscous behaviour. Comparison between the two RANS models showed little difference in terms of velocity contours at OGV trailing edge and diffuser exit. In terms of overall diffuser performance (static pressure recovery and total pressure loss coefficients), the high- Re model was shown to agree well with experimental data. The preliminary LES study indicates the highly unsteady character of the OGV wake flow, but requires improved treatment of inlet conditions.
摘要: 在大流量气-气喷注器单喷嘴工况研究的基础上,为研究其在具有单元交互作用的多喷嘴工况下的燃烧特性,设计了多喷嘴推力室.喷注单元为剪切混合式单元,并具有高氢/氧速度比和氧喷嘴扩口设计,采用了能够模拟真实发动机工况的7单元同心圆排布的推力室头部结构,在对喷注单元的排布间距优化设计基础上,开展了热试车试验研究和仿真分析.结果表明所设计的喷注器在多喷嘴工况下燃烧稳定,能够在额定参数设计的燃烧室内,在SSME(space shuttle main engine)主喷注单元流量的3.7倍大流量工况下燃烧效率达到99%以上,并显示出良好的喷注器自身和带来的燃烧室身部热防护特性.