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Volume 33, Issue 6
Displaying 1-5 of 5 articles from this issue
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Technical Papers
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Shin OBA, Toshiaki KANEMOTO2005 Volume 33 Issue 6 Pages 336-343
Published: 2005
Released on J-STAGE: October 30, 2006
JOURNAL FREE ACCESSTurbo-pumps have weak points, such as the pumping operation becomes unstable in the rising portion of the head characteristic and / or the cavitation occurs under the low suction head. To overcome simultaneously the both weak points, the authors have proposed the unique pumping system which composed of counter-rotating type impellers and the motor with double rotors. The impeller speeds are self-controlled in response to the pumping discharge. In this paper, the flow conditions around the counter-rotating impellers are discussed experimentally in connection with the rotational speeds.View full abstractDownload PDF (2006K) -
Tadashi TSUKAMOTO, Morihito INAGAKI, Tadahiko WATANABE, Shoichi YAMATO ...2005 Volume 33 Issue 6 Pages 344-351
Published: 2005
Released on J-STAGE: October 30, 2006
JOURNAL FREE ACCESSIn Japan, there still are many undeveloped hydro-power sites of low head which provide the output less than 100kW. To utilize them efficiently and effectively, the authors have developed a micro tubular turbine under the wide range operation. As the further study, we treat the following issues in this paper: one is the flow mechanism of the increase in hydraulic efficiency with the serial arrangement of tubular turbines, which is aimed to widen their application for higher head sites. And the other is the investigation of cavitation characteristics of the micro tubular turbine associated with the cam-combination. An interesting finding is that there is suitable cam-combination for the cavitation characteristic, which is better than that of the on-cam condition. It is possible to increase the discharge up to 12% by the proposed cam-combination.View full abstractDownload PDF (1865K) -
Kusuo OKUMA, Kazuki TAKENOUCHI, Akinori FURUKAWA, Toshiaki SETOGUCHI2005 Volume 33 Issue 6 Pages 352-357
Published: 2005
Released on J-STAGE: October 30, 2006
JOURNAL FREE ACCESSAxial flow turbines, developed for wave power conversion turbine systems, are focused for utilizing extra-low head tidal power. Their turbine characteristics in steady flow are compared with that of previously investigated Darrieus turbine, and turbine behaviors operating in a flow induced by tidal range are numerically estimated. The impulse turbine with self-pitch-controlled guide vanes extracts the highest power generation under the fixed condition of pond surface-area as its good efficiency and yielding the largest head difference between the sea and pond surface levels. On the other hand, Darrieus turbine indicates the most economical advantage by reason of its simple structure and yielding the highest flow rate.View full abstractDownload PDF (1567K) -
Tadashi KOZU, Takahiro NISHIOKA, Kenichi NAKAMURA2005 Volume 33 Issue 6 Pages 358-364
Published: 2005
Released on J-STAGE: October 30, 2006
JOURNAL FREE ACCESSExperimental research on jet fan was carried out in order to clarify blade noise from a jet fan. Based on Sharland's and Fukano's theories or experimental results, a new blade noise prediction method was proposed. New prediction method is separated into two categories, such as broadband frequency noise induced by vortex shedding mechanism at blade trailing edge and discrete frequency noise induced by wake-rotor interaction. Two types jet fans (named Base fan and New fan) with different rotation speed were investigated. Predicted new fan noise level and frequency by proposed method were consistent with measured new fan noise level and frequency, especially Nz component.View full abstractDownload PDF (1798K) -
Kazuhiro TSURUTA2005 Volume 33 Issue 6 Pages 365-372
Published: 2005
Released on J-STAGE: October 30, 2006
JOURNAL FREE ACCESSIn order to design a half ducted fan it is necessary to estimate axial induced velocity. In the present study, two-dimensional analysis in which the induced velocity is calculated by combining the momentum and angular momentum theory with the blade element theory is developed. Using spreadsheet with macro easily performs this analysis. The calculation results agree fairly well with the experiment of PQ characteristics in the region of ordinary fan operation. The prediction of fan head and rotational speed by using this method reaches the same level of accuracy as that of CFD computation.View full abstractDownload PDF (1773K)
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