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首页> 外文学位 >Large eddy simulations of turbulent flows on graphics processing units: Application to film-cooling flows .
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Large eddy simulations of turbulent flows on graphics processing units: Application to film-cooling flows .

机译：图形处理单元上湍流的大涡模拟：在膜冷却流中的应用。

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摘要

Computational Fluid Dynamics (CFD) simulations can be very computationally expensive, especially for Large Eddy Simulations (LES) and Direct Numerical Simulations (DNS) of turbulent ows. In LES the large, energy containing eddies are resolved by the computational mesh, but the smaller (sub-grid) scales are modeled. In DNS, all scales of turbulence are resolved, including the smallest dissipative (Kolmogorov) scales. Clusters of CPUs have been the standard approach for such simulations, but an emerging approach is the use of Graphics Processing Units (GPUs), which deliver impressive computing performance compared to CPUs. Recently there has been great interest in the scientific computing community to use GPUs for general-purpose computation (such as the numerical solution of PDEs) rather than graphics rendering.;To explore the use of GPUs for CFD simulations, an incompressible Navier-Stokes solver was developed for a GPU. This solver is capable of simulating unsteady laminar flows or performing a LES or DNS of turbulent ows. The Navier-Stokes equations are solved via a fractional-step method and are spatially discretized using the finite volume method on a Cartesian mesh. An immersed boundary method based on a ghost cell treatment was developed to handle flow past complex geometries. The implementation of these numerical methods had to suit the architecture of the GPU, which is designed for massive multithreading. The details of this implementation will be described, along with strategies for performance optimization. Validation of the GPU-based solver was performed for fundamental bench-mark problems, and a performance assessment indicated that the solver was over an order-of-magnitude faster compared to a CPU.;The GPU-based Navier-Stokes solver was used to study film-cooling flows via Large Eddy Simulation. In modern gas turbine engines, the film-cooling method is used to protect turbine blades from hot combustion gases. Therefore, understanding the physics of this problem as well as techniques to improve it is important. Fundamentally, a film-cooling configuration is an inclined cooling jet in a hot cross-flow. A known problem in the film-cooling method is jet lift-off, where the jet of coolant moves away from the surface to be cooled due to mutual vortex induction by the counter-rotating vortex pair embedded in the jet, resulting in decreased cooling at the surface. To counteract this, a micro-ramp vortex generator was added downstream of the film-cooling jet, which generated near-wall counter-rotating vortices of opposite sense to the vortex pair in the jet. It was found that the micro-ramp vortices created a downwash effect toward the wall, which helped entrain coolant from the jet and transport it to the wall, resulting in better cooling. Results are reported using two film-cooling configurations, where the primary difference is the way the jet exit boundary conditions are prescribed. In the first configuration, the jet is prescribed using a precursor simulation and in the second the jet is modeled using a plenum/pipe configuration. The latter configuration was designed based on previous wind tunnel experiments at NASA Glenn Research Center, and the present results were meant to supplement those experiments.
机译：计算流体动力学（CFD）仿真的计算量可能非常大，特别是对于湍流的大型涡流仿真（LES）和直接数值仿真（DNS）而言。在LES中，较大的包含能量的涡流通过计算网格解决，但对较小的（子网格）比例进行建模。在DNS中，解决了所有湍流尺度，包括最小的耗散（Kolmogorov）尺度。 CPU集群一直是此类仿真的标准方法，但是新兴的方法是使用图形处理单元（GPU），与CPU相比，图形处理单元可提供令人印象深刻的计算性能。最近，科学计算界对使用GPU进行通用计算（例如PDE的数值解）而不是图形渲染表现出极大的兴趣；要探索将GPU用于CFD仿真的不可压缩的Navier-Stokes求解器是为GPU开发的。该求解器能够模拟不稳定的层流或执行湍流的LES或DNS。 Navier-Stokes方程通过分数步法求解，并在笛卡尔网格上使用有限体积法在空间上离散。开发了一种基于重影细胞处理的浸入边界方法来处理流经复杂几何形状的流。这些数值方法的实现必须适合为大规模多线程设计的GPU体系结构。将描述此实现的详细信息以及性能优化策略。针对基本基准问题对基于GPU的求解器进行了验证，性能评估表明该求解器比CPU快了一个数量级;基于GPU的Navier-Stokes求解器用于通过大涡模拟研究膜冷却流。在现代燃气涡轮发动机中，薄膜冷却方法用于保护涡轮叶片免受高温燃烧气体的侵害。因此，了解此问题的物理原理以及改进该问题的技术很重要。从根本上说，薄膜冷却装置是热流中的倾斜冷却喷嘴。薄膜冷却方法中的一个已知问题是射流升起，其中冷却剂射流由于嵌入在射流中的反向旋转涡流对的相互涡流感应而从待冷却表面移开，从而导致冷却能力降低。表面。为了解决这个问题，在薄膜冷却喷嘴的下游增加了一个微斜坡涡流发生器，该发生器产生了与喷嘴中的涡流对相反方向的近壁反向旋转涡流。发现微斜坡涡流向壁产生了向下冲洗效果，这有助于从喷嘴夹带冷却剂并将其输送到壁上，从而实现更好的冷却效果。使用两种薄膜冷却配置报告结果，其中主要区别在于规定射流出口边界条件的方式。在第一种配置中，使用前体模拟来指定射流，而在第二种配置中，使用充气/管道配置来对射流建​​模。后一种配置是根据美国宇航局格伦研究中心以前的风洞实验设计的，目前的结果是对那些实验的补充。

著录项

  • 作者

    Shinn, Aaron F.;

  • 作者单位

    University of Illinois at Urbana-Champaign.;

  • 授予单位 University of Illinois at Urbana-Champaign.;
  • 学科 Engineering Aerospace.;Computer Science.;Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 233 p.
  • 总页数 233
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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