二重反転形小型冷却ファンのLES解析

抄録

In a small cooling fan with contra-rotating impellers, it is necessary to clarify the influence of the tip leakage vortex on the flow field of the rear impeller because the tip leakage vortex generated by the front impeller enters the rear impeller. However, RANS, which is generally used in the design and development of turbomachines, can not solve the flow phenomena related to the small vortex. Therefore, in this research, LES analysis is performed for the contra-rotating small cooling fan that are commercially available for server cooling, and the flow phenomena such as tip leakage vortex is investigated. We aim to elucidate the complex internal flow. If complex flow phenomena such as tip leakage vortices can be predicted with high accuracy, it may lead to the elucidation of fan noise sources, and it may be possible to establish a design method of the contra-rotating small sized fan for noise reduction. In this report, LES analysis is performed on a small cooling fan with contra-rotating impellers, and the internal flow is considered focusing on the behavior of tip leakage vortex from the calculation results. As a result, it was confirmed that the tip leakage vortex had a large influence on the low velocity area in tip clearance.