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Volume 36, Issue 8
Displaying 1-4 of 4 articles from this issue
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Technical Papers
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Takashi ATONO, Jun-Ho KIM, Koichi ISHIZAKA, Satoshi WATANABE, Akinori ...2008 Volume 36 Issue 8 Pages 477-482
Published: 2008
Released on J-STAGE: June 17, 2009
JOURNAL FREE ACCESSThe attachment of inducer in front of main impeller is a powerful method to improve cavitation performance. In operating condition at partial flow rate and extremely low suction pressure, however cavitation surge oscillation occurs. As the cavitation surge oscillation with low frequency occurs in a close relation between the inlet back-flow cavitation and the growth of blade cavity to the throat section of blade passage, one method of installing an axi-asymmetrical plate upstream of inducer is proposed to suppress the oscillation. It is considered as the suppression mechanism of oscillation conceptually to avoid making flow at all throat sections unstable simultaneously due to inlet flow distortion by suction axi-asymmetrical plate. In the present study, cavitation behaviors in the inducer is observed with distributing multi-cameras circumferentially, recording simultaneously and reconstructing multi-photos on one plane field as moving a linear cascade. Observed results are utilized for discussion with other measuring results as casing wall pressure distribution. Then the suppression mechanism of oscillation by installing axi-asymmetrical inlet plate will be clarified in more details.View full abstractDownload PDF (1687K) -
Takayuki SUZUKI, Romain PRUNIÉRES, Hironori HORIGUCHI, Yoshinob ...2008 Volume 36 Issue 8 Pages 483-489
Published: 2008
Released on J-STAGE: June 17, 2009
JOURNAL FREE ACCESSIn a turbomachinery operated at the supercritical speed, a self-excited vibration can cause serious damages to both rotor and stator parts of the machine. The forces resulting from such vibrations are commonly called "rotordynamic fluid forces". The present paper reports about the rotordynamic fluid forces on an open-type centrifugal impeller. By generating an eccentricity, rotordynamic fluid forces were measured on an open-type centrifugal impeller with the type number of 0.33 in the cases with one vaneless and two vaned diffusers under the whirling motion. It was found that there is a destabilizing region near the whirl speed ratio ω/Ω =1 at design and lower flow rate in addition to a destabilizing region at small positive whirl ratios.View full abstractDownload PDF (699K) -
(Hybrid Method for Combining PIV with CFD)Futoshi TANAKA, Kiyoshi KAWAGUCHI, Masahiro TOMIOKA, Keiichiro KAWASHI ...2008 Volume 36 Issue 8 Pages 490-498
Published: 2008
Released on J-STAGE: June 17, 2009
JOURNAL FREE ACCESSA new estimation method of pressure from the velocity data of particle image velocimetry (PIV) is discussed in this paper. The new method is a hybrid method that combines PIV with the computational fluid dynamics (CFD) simulation to supplement the resolution of the PIV method. Flow visualization and PIV analysis of the flow field around the darrieus wind turbine with flow guides were executed. The guides to control the flow were arranged around the darrieus wind turbine. The velocity field around wing of the darrieus wind turbine was obtained from the PIV method. The pressure field around the wing was estimated from the velocity field by using the developed hybrid method. The thrust that acted on the wing was obtained from the pressure distribution. The thrust in the θ=30 degrees and the θ=180 degrees increased by the flow guides. However, the thrust in the θ=330 degrees decreased. As a result, the average thrust decreased from -0.19 to -0.21.View full abstractDownload PDF (2268K) -
Naoki MATSUSHITA, Akinori FURUKAWA, Satoshi WATANABE, Kusuo OKUMA, Tom ...2008 Volume 36 Issue 8 Pages 499-506
Published: 2008
Released on J-STAGE: June 17, 2009
JOURNAL FREE ACCESSA centrifugal pump, the pumping action of which could be highly kept even at an air-water two-phase flow condition of inlet void fraction more than 30 % in the range of relatively high water flow rate, has been developed. The pump consists of a tandem arrangement of double rotating cascades and blades of outer cascade have higher outlet angle more than 90°. In design of the two-phase flow pump for various sized and operating conditions, similarity relations of geometric dimensions to hydraulic performances is very useful. The similarity relations of rotational speed, impeller diameter and blade height are investigated for the developed impeller in the present paper. As the results, the similarity law of rotational speed and impeller diameter is verified experimentally even in two-phase flow condition. In addition, influences of blade height on air-water two-phase flow performances indicate a little difference from the similarity relations.View full abstractDownload PDF (1009K)
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