• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文会议>ASME turbine blade tip technical symposium 2013 : Turbine blade tip steady and unsteady aerodynamics ... >DIRECT NUMERICAL SIMULATIONS OF A TRANSONIC TIP FLOW WITH FREE-STREAM DISTURBANCES
【24h】

DIRECT NUMERICAL SIMULATIONS OF A TRANSONIC TIP FLOW WITH FREE-STREAM DISTURBANCES

机译：具有自由流扰动的跨音速流的直接数值模拟

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

In this paper we use direct numerical simulation to investigate the unsteady flow over a model turbine blade-tip at engine scale Reynolds and Mach numbers. The DNS is performed with a new in-house multi-block structured compressible Navier-Stokes solver purposely developed for exploiting high-performance computing systems. The particular case of a transonic tip flow is studied since previous work has suggested compressibility has an important influence on the turbulent nature of the separation bubble at the inlet to the gap and subsequent flow reattachment. The effects of free-stream turbulence, cross-flow and pressure-side boundary-layer on the tip flow aerodynamics and heat transfer are investigated. For 'clean' in-flow cases we find that even at engine scale Reynolds numbers the tip flow is intermittent in nature (neither laminar nor fully turbulent). The breakdown to turbulence occurs through the development of spanwise modes with wavelengths around 25% of the gap height. Cross-flows of 25% of the streamwise gap exit velocity are found to increase the stability of the tip flow, and to significantly reduce the turbulence production in the separation bubble. This is predicted through in-house linear stability analysis, and confirmed by the DNS. For the case when the inlet flow has free-stream turbulence, viscous dissipation and the rapid acceleration of the flow at the inlet to the tip-gap causes significant distortion of the vorticity field and reductions of turbulence intensity as the flow enters the tip gap. This means that only very high turbulence levels at the inlet to the computational domain significantly affect the tip heat transfer. The DNS results are compared with RANS predictions using the Spalart-Allmaras and k - ω SST turbulence models. The RANS and DNS predictions give similar qualitative features for the tip flow, but the size and shape of the inlet separation bubble and shock positions differ noticeably. The RANS predictions are particularly insensitive to free-stream turbulence.
机译：在本文中，我们使用直接数值模拟来研究在模型发动机雷诺数和马赫数下涡轮叶尖上的非恒定流动。使用新的内部多块结构可压缩Navier-Stokes求解器执行DNS，该求解器专门为开发高性能计算系统而开发。由于先前的工作表明可压缩性对间隙入口处的分离气泡的湍流特性以及随后的流动重新附着有重要影响，因此研究了跨音速尖端流动的特殊情况。研究了自由流湍流，错流和压力侧边界层对叶尖流动空气动力学和传热的影响。对于“干净”的流入情况，我们发现即使在发动机比例雷诺数的情况下，叶尖流动本质上也是断断续续的（既不是层流也不是完全湍流的）。湍流的破坏是通过展宽模式的发展而发生的，展宽模式的波长约为间隙高度的25％。已发现流向间隙出口速度的25％的错流会增加尖端流的稳定性，并显着降低分离气泡中的湍流产生。这是通过内部线性稳定性分析预测的，并由DNS确认。对于入口流具有自由流湍流的情况，粘性耗散和入口处的流向叶尖间隙的快速加速会导致涡流场发生明显变形，并在流进入叶尖间隙时降低湍流强度。这意味着在计算域的入口处只有非常高的湍流水平会显着影响尖端的传热。使用Spalart-Allmaras和k-ωSST湍流模型将DNS结果与RANS预测进行比较。 RANS和DNS预测为叶尖流动提供了类似的定性特征，但是入口分离气泡的大小和形状以及激波位置明显不同。 RANS的预测对自由流湍流特别不敏感。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号