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Investigation of novel turbulence modeling techniques for gas turbines and aerospace applications.

机译：对燃气轮机和航空航天应用的新型湍流建模技术的研究。

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摘要

Standard eddy-viscosity models lack curvature and system rotation sensitized terms in their formulation. Hence they fail to capture the effects of curvature and system rotation on turbulence anisotropy. As part of this effort, an algebraic expression for a characteristic rotation term is developed and tuned with the help of rotating homogeneous shear flow. This formulation is primarily based upon the rotation and curvature sensitized eddy-viscosity coefficient developed by York et al. (2009). A new scalar transport equation loosely based on Durbin's wall normal turbulent velocity scale (Durbin, 1991) is introduced to account for the modification in turbulence structure due to system rotation and curvature effects. The added transport equation also introduces history effects and stability in the solution with small increase in computational cost. The eddy-viscosity is redefined based on new turbulent velocity scale and hence the effects of rotation and streamline curvature are introduced into the mean momentum equation. A number of canonical test cases with significant curvature and rotation effects along with a cyclone flow, a representative of complex industrial flows, are considered for model validation.;A hybrid modeling framework combines the strength of RANS in boundary layers and LES in separated shear layers to alleviate the weaknesses of RANS and limitations of LES model in some complex flows. A recently proposed hybrid RANS-LES modeling framework uses a weighing parameter that dynamically determines the RANS and LES regions based on solution statistics. The hybrid modeling methodology is implemented on a normal jet in crossflow, and a film cooling case for the purpose of model validation and evaluation.;The final goal of the proposed effort is to combine advanced RANS modeling capability with LES using the new hybrid modeling framework. Specifically, the curvature and rotation sensitive RANS model developed here is coupled with commonly used LES models to produce a novel model for complex turbulent flows with the potential to improve accuracy of CFD predictions (versus existing RANS models) as well as significantly reduce the computational expense (versus existing LES models). Performance of the model form hence developed is evaluated on a cyclone flow case.
机译：标准的涡流粘度模型在其公式中缺少曲率和系统旋转敏感项。因此，它们无法捕获曲率和系统旋转对湍流各向异性的影响。作为这项工作的一部分，借助旋转均匀剪切流，开发并调整了特征旋转项的代数表达式。该公式主要基于约克等人开发的旋转和曲率敏感的涡流-粘度系数。 （2009）。引入了一个新的基于Durbin壁法向湍流速度尺度的标量输运方程（Durbin，1991），以解释由于系统旋转和曲率效应而引起的湍流结构的变化。所增加的输运方程式还引入了历史效应和解决方案的稳定性，而计算量却很少增加。基于新的湍流速度尺度重新定义了涡流粘度，因此将旋转和流线曲率的影响引入了平均动量方程。考虑使用许多具有显着曲率和旋转效果的典型测试案例以及代表复杂工业流程的旋风流进行模型验证。混合建模框架结合了边界层RANS和分离剪切层LES的强度以减轻RANS的缺点和LES模型在某些复杂流程中的局限性。最近提出的混合RANS-LES建模框架使用加权参数，该加权参数基于解决方案统计信息动态确定RANS和LES区域。混合建模方法是在横流的常规射流和薄膜冷却箱上实现的，以进行模型验证和评估。拟议工作的最终目标是使用新的混合建模框架将先进的RANS建模能力与LES相结合。具体来说，此处开发的对曲率和旋转敏感的RANS模型与常用的LES模型结合使用，可以为复杂的湍流生成一个新颖的模型，从而有可能提高CFD预测的准确性（相对于现有的RANS模型），并显着降低了计算费用（与现有的LES模型相对）。因此开发的模型形式的性能在旋风分离器情况下进行评估。

著录项

  • 作者

    Dhakal, Tej Prasad.;

  • 作者单位

    Mississippi State University.;

  • 授予单位 Mississippi State University.;
  • 学科 Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2013
  • 页码 150 p.
  • 总页数 150
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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