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Volume 35, Issue 8
Displaying 1-3 of 3 articles from this issue
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Technical Papers
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Design Optimization of a High Specific Speed Francis Turbine Using Multi-Objective Genetic AlgorithmKazuyuki NAKAMURA, Sadao KUROSAWA2007 Volume 35 Issue 8 Pages 474-479
Published: 2007
Released on J-STAGE: September 24, 2008
JOURNAL FREE ACCESSA design optimization system for Francis turbine was developed. The system consists of design program and CFD solver. Flow passage shapes are optimized automatically by using the system with Muiti-Objective Genetic Algorithm (MOGA). In this study, the system was applied to a high specific speed Francis turbine (nsp=250m-kW). The runner profile and the draft tube shape were optimized to decrease hydraulic losses. As the results , it was shown that the turbine efficiency was improved in wide operating range, furthermore, the height of draft tube was reduced with the hydraulic performance kept.View full abstractDownload PDF (997K) -
Kiyoshi KAWAGUCHI, Kenichi OKUI, Masahiro KUWAUMI2007 Volume 35 Issue 8 Pages 480-488
Published: 2007
Released on J-STAGE: September 24, 2008
JOURNAL FREE ACCESSIn 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 obstacle on the fan characteristics and fan noise are investigated. The results are that the fan noise at low frequency region increases with bringing an obstacle located upper region of fan inlet close to a fan and the fan noise at over all frequency region increases with bringing an obstacle located whole region of fan inlet close to a fan, and that the fan efficiency at the large flow rate region is decreased with bringing an obstacle close to a fan.View full abstractDownload PDF (1491K) -
Takeshi TAKANASHI, Akimasa IDENO, Yusuke OHTSUKA, Yoshio UEDA, Masahir ...2007 Volume 35 Issue 8 Pages 489-495
Published: 2007
Released on J-STAGE: September 24, 2008
JOURNAL FREE ACCESSIn this paper, we proposed auxiliary magnets applied to the passive magnetic bearing using eddy current. The characteristics of restoring force and braking torque for this bearing are calculated by magnetic field analysis using finite element method. In this calculation, the restoring force is slightly increased and the braking torque is decreased in comparison with the magnetic bearing without auxiliary magnets. Therefore the installation of the auxiliary magnets leads to high performance for the magnetic bearing.View full abstractDownload PDF (1151K)
Review
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