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Numerical Investigation of Unsteady Flow in an Axial Flow Turbomachineries

轴流式涡轮机械中非定常流动的数值研究

基本信息

批准号：
12555046
负责人：
MIYAKE Yutaka
金额：
$ 8.7万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-12555046/
关键词：
Axial Flow Fan Rotating Stall Numerical Simulation Turbomachinery Vortex Shading Cascade Unsteady Flow Leakage Flow

项目摘要

Operation of an axial flow turbomachineries falls into unstable for low flow rate conditions because of the head increase with flow. Prediction of stall and understanding of unsteady feature with stall is essential for the design of such fluid machineries. However, the industrial design is based on some empirical law. In our study, we reproduced numerically the flow with stall cell by means of the direct numerical simulation technique and investigated the mechanism of unsteady flow. With a limitation of current computers, we applied the parallel computation to flows in multiple passages of single-stage rotor without stator. Two kinds of cascade are selected because the experimental data were available. For small aspect ratio and small number of blades, the numerical result did not show a stall cell even for the stall condition in experiment. On another condition, clear and developed stall cells were obtained, which may be the first success by the numerical simulation. Although the quantitative agreement between numerical and experimental results was not sufficient due to the lack of computational resolution, we believe it agrees qualitatively with experimental observation. It was found that the stall cell had a vortex structure stretched into the upstream direction from the cascade. We think the propagation of it is not caused by the blocking effect by the cell, but the convection of vortex. This suggests the estimation of rotating velocity of cell should be reconsidered.

轴流式水轮机由于水头随流量增加而增大，在小流量工况下运行福尔斯不稳定。失速的预测和失速时非定常特性的了解是此类流体机械设计的基础。然而，工业设计是建立在一定的经验规律基础上的。本文采用直接数值模拟技术，对带失速单元的流动进行了数值再现，并对非定常流动的机理进行了研究。针对现有计算机的局限性，本文采用并行计算的方法对无静叶单级转子多通道流动进行了研究。由于实验数据的可靠性，本文选择了两种叶栅。对于小展弦比和小叶片数的情况，即使在实验失速条件下，数值计算结果也没有显示出失速胞。在另一种情况下，得到了清晰、发达的失速区，这可能是数值模拟的首次成功。虽然数值和实验结果之间的定量协议是不够的，由于缺乏计算分辨率，我们相信它同意定性与实验观察。结果表明，失速胞具有从叶栅向上游方向延伸的涡结构。我们认为它的传播不是由单体的阻挡作用引起的，而是由涡旋的对流引起的。这表明细胞旋转速度的估计应该重新考虑。