超小型ラジアルタービンの実現に向けた空力的課題の検討 : 第二部:チップクリアランスの影響

概要

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Feasibility of "finger-top" ultra-micro radial inflow turbine is studied numerically. The blades of such small turbine have constant cross-section from hub to tip and do not have twist, therefore three-dimensional optimize is not allowed. The Reynolds number will be one or two order of magnitude lower, the heat transfer will be predominant, and the relative tip clearance height becomes larger than conventional turbines. These aerodynamic concerns are discussed based on the numerical simulation of the flowfield inside two-dimensional turbine. The results showed that decrease in the length-scale enlarge the relative clearance height and it significantly deteriorate the performance. Meanwhile, it strengthen the scraping flow which suppress the clearance flow. Therefore, it may be possible to operate the ultra-micro turbine with manageable performance if the clearance height is maintained smaller than the height of the scraping flow.
社団法人日本ガスタービン学会の論文
2005-05-20