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.

由于水头随流量增加，轴流式涡轮机的运行在低流量条件下会变得不稳定。失速预测和对失速不稳定特征的理解对于此类流体机械的设计至关重要。然而，工业设计是基于一些经验规律的。在我们的研究中，我们通过直接数值模拟技术对带有失速单元的流动进行了数值再现，并研究了非定常流动的机理。由于现有计算机的限制，我们将并行计算应用于单级无定子转子的多通道流动。由于已有实验数据，因此选择了两种级联。对于小展弦比和少量叶片，即使在实验失速条件下，数值结果也没有显示出失速单元。在另一个条件下，获得了清晰且发达的失速单元，这可能是数值模拟的首次成功。尽管由于缺乏计算分辨率，数值结果和实验结果之间的定量一致性不够，但我们相信它与实验观察定性地一致。发现失速室具有从叶栅向上游方向延伸的涡流结构。我们认为它的传播不是由细胞的阻挡作用引起的，而是涡流的对流引起的。这表明应该重新考虑细胞旋转速度的估计。