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Technical Papers

小型軸流ファンの性能に及ぼす流入乱れの影響

(乱流格子による乱れがファン特性と騒音に及ぼす影響)

川口清司, 奥井健一, 桑海正宏

2005 年 33 巻 12 号 p. 723-731
発行日: 2005年
公開日: 2007/01/10

DOIhttps://doi.org/10.11458/tsj.33.723

ジャーナルフリー

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In recent years a compact axial flow fan has been used for cooling of electronic instrument because of its large flow rate. The improvement of fan efficiency and the noise reduction are required considerably. However the electronic parts located upstream fan generate the turbulence of inlet flow, whose effects on fan characteristic and noise are not clarified. In this paper the effects of turbulence of inlet flow generated by grid on the fan characteristics and fan noise are investigated. The results are that in the case of same turbulence intensity the turbulence having large vortex causes larger fan noise than the turbulence having small vortex, and that the fan efficiency at the large flow rate region is improved with the increase of turbulence intensity.

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多目的遺伝的アルゴリズムによるフランシス水車ランナの最適化設計

榎本保之, 黒沢貞男, 鈴木敏暁

2005 年 33 巻 12 号 p. 732-737
発行日: 2005年
公開日: 2007/01/10

DOIhttps://doi.org/10.11458/tsj.33.732

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An optimization system coupled CFD and design tool of Francis turbine runner shape to Multi-Objective Genetic Algorithm (MOGA) is presented. The system can automatically optimize runner shape according to objective functions. The system was applied for Francis turbine runner, whose specific speed is 80 m-kW and the objective functions were selected hydraulic losses at three operating points. As the result of the optimization, many optimized runners, which have various performances, were obtained. Model test was conducted for the optimized runner and it was confirmed that the optimized runner has high efficiency characteristics in wide operating range.

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ウェルズタービンにおけるガイドベーンの効果

鈴木正己

2005 年 33 巻 12 号 p. 738-744
発行日: 2005年
公開日: 2007/01/10

DOIhttps://doi.org/10.11458/tsj.33.738

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Guide vanes are installed in the Wells turbine in order to improve its efficiency, self-rotating characteristics and off design performance with stall. This works attempts to explain the role of these guide vanes on the basis of momentum theory. It is shown that the upstream vanes are more effective in enhancing efficiency than the downstream ones. A design method for guide vanes is suggested based on experimental data and potential theory. Experimental studies carried out by the authors do confirm the theory proposed.

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