LES and PTV Measurement of Turbulent Flow in Expanding Concentric Annular Flow-Passage with Rotating Inner-Wall

旋转内壁同心环形流道内紊流的LES和PTV测量

基本信息

批准号：
18560154
负责人：
MURATA Akira
金额：
$ 2.48万
依托单位：
Tokyo University of Agriculture and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18560154/
关键词：
Fluid engineering Flow visualization Flow instability Computational fluid dynamics Particle image velocimetry Large eddy simulation Turbulent flow Heat transfer ラージエディシミュレーション

项目摘要

An annular flow passage with a rotating inner wall is widely utilized in industrial apparatuses, and the examples are centrifuges, journal bearings, and rotating machinery. Therefore, the understanding of the flow and heat transfer in this type of flow passage is important In this flow passage, multiple flow-instability factors can simultaneously affect; shear flow instability due to through flow and/or inner-wall rotation and centrifugal flow instability due to peripheral and/or through-flow streamline curvatures. In the real applications, most of the flow becomes turbulent, and the cross-sectional area changes in the through-flow direction, which further complicates the phenomena. The objective of this study is to investigate the turbulent flow affected by the multiple flow-instability factors by performing Large Eddy Simulation (LES) and Particle Tracking Velocimetry (PTV) measurement.The two types of flow passages were examined : concave and convex types named after the shape of th … More e inner wall. In the PTV measurement, two-frame method was used, and the time-averaged velocities and the turbulence intensities were calculated. In the experiment, though-flow Reynolds number, Re, was varied from 1000 to 10000, and the Taylor number, Ta, was varied from 0 to 8000. For Re=1000, the inner-wall rotation caused the increased turbulence intensity in the downstream region. For Re=10000, the turbulence intensity increased in both the upstream and downstream regions. The inner wall rotation induced the reversed flow at the outlet.The LES was performed in the curvilinear coordinate system using the second order finite difference method. The concave-and convex-type passages were treated for Re=1000(constant) and Ta=0-4000. The peripheral computational size was varied among 45, 90, and 360 degrees. In the LES result, the flow structure was peripherally uniform near the inlet, and the inner wall rotation induced turbulence in the downstream region. The vortex structure was dependent on the Taylor number, the flow passage type, and the position in the passage (upstream/downstream and near inner/outer wall). The heat transfer coefficient profile became complicated due to the reversed flow and the turbulent transfer. The examination of wall shear stress and torque coefficient further clarified the flow structure difference in each flow passage. Less

具有旋转内壁的环形流道广泛应用于工业设备中，例如离心机、轴颈轴承和旋转机械，因此，了解此类流道中的流动和传热非常重要。在实际应用中，多种流动不稳定因素会同时影响；由于通流和/或内壁旋转而导致的剪切流不稳定以及由于外围和/或通流流线曲率而导致的离心流不稳定。变得湍流，并且流通方向上的横截面积发生变化，这使现象进一步复杂化。本研究的目的是通过执行大涡模拟（LES）来研究受多种流动不稳定因素影响的湍流。检测了两种类型的流道：以内壁形状命名的凹型和凸型。在 PTV 测量中，采用了两帧法。在实验中，通流雷诺数 Re 在 1000 到 10000 之间变化，泰勒数 Ta 在 0 到 8000 之间变化。 Re=1000时，内壁旋转导致下游区域湍流强度增加；当Re=10000时，上游区域湍流强度增加。内壁旋转引起出口处的反向流动。使用二阶有限差分方法在曲线坐标系中进行LES，凹凸型通道被处理为Re=1000（常数）。 Ta=0-4000，外围计算尺寸在45度、90度和360度之间变化。在LES结果中，入口附近的流动结构是外围均匀的，而内部的。壁旋转引起下游区域的湍流，涡流结构取决于泰勒数、流道类型和通道位置（上游/下游和靠近内壁/外壁）。对逆流和湍流传递的壁面剪应力和扭矩系数的检验进一步阐明了各流道内的流动结构差异。