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 : 第一部:レイノルズ数と熱伝達による影響

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 flow field inside two-dimensional turbine. The results showed that the two-dimesional blade shape does not deteriorate the flowfield within blade passage, but severe separation is observed at the exducer where the flow turns from radial direction to axial direction. The decrease in the Reynolds number does not have catastrophic effect except increase in the boundary layer thickness. The primary effect of the heat transfer is the deviation of rotor relative inlet flow angle, but the numerical results also indicated that the boundary layer over the isothermal wall separates easier than that over the adiabatic wall.
社団法人日本ガスタービン学会の論文
2005-05-20