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Volume 30, Issue 2
Displaying 1-8 of 8 articles from this issue
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Masao OSHIMA, Naokazu KUBOTA2002 Volume 30 Issue 2 Pages 65-69
Published: February 10, 2002
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSDownload PDF (2439K) -
Takahide NAGAHARA, Tadashi SATO, Seiji KAWABATA, Tomoyoshi OKAMURA2002 Volume 30 Issue 2 Pages 70-75
Published: February 10, 2002
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSThe effect of submerged vortices on the hydraulic forces of a mixed flow pump impeller was studied using a model pump with an intake sump. The experiments comprise observation of submerged vortices reaching the impeller with a high-speed video camera and measurement of the velocity distribution around the submerged vortex by particle tracking velocimetry (PTV) to obtain the strength of the vortex. Measurement results are compared with CFD calculation to evaluate their accuracy. Hydraulic forces on the model pump when the submerged vortex reached the pump impeller was measured with load cells. The relationship between the strength of the submerged vortex and the effect of the vortex on the fluctuation of the hydraulic forces are described.View full abstractDownload PDF (7015K) -
Masatake MAEKAWA, Kazuyoshi MIYAGAWA, Yutaka KAWATA2002 Volume 30 Issue 2 Pages 76-81
Published: February 10, 2002
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSThe final target of this research is to establish a method for optimizing the design of a draft tube that is installed to recover the static pressure of water flow discharged from a hydraulic turbine runner. For this purpose, detailed measurements of the draft tube internal flows were implemented by using a draft tube element model to make it easy to control the inlet swirl flows, and the measured data was compared with the result of the flow analysis. Since the static internal fl ow in the draft tube was accurately simulated with three-dimensional viscosity analysis using a turbulence model, it proved useful as a designing tool for clarifying flow phenomena. And it becomes clear that the internal flows and the characteristics are largely influenced by the inlet flow velocity distribution, so this fact must be taken into consideration when designing a runner.View full abstractDownload PDF (8128K) -
Choon-Man JANG, Masato FURUKAWA, Masahiro INOUE, Hideaki MAEDA, Masahi ...2002 Volume 30 Issue 2 Pages 82-90
Published: February 10, 2002
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSThree-dimensional vortical flow structure and separeted flow topology near the casing wall in a mixed flow pump impeller with high specific speed have been investigated by a Reynolds-averaged Navier-Stokes (RANS) flow simulation. The simulation shows that a tip leakage vortex formed close to the leading edge of the impeller tip suction side grows in the tangential direction even at the design operating condition, thus impinging on the adjacent blade leading edge. This interaction between the leakage vortex and the blade pressure surface causes a vortex breakdown and an expansion of the leakage vortex near the pressure surface. The tip leakage flow causes the casing wall boundary layer to separate along the leakage vortex. As a result of the breakdown of the leakage vortex, the separation region due to the tip leakage flow is forced out into the upstream ofthe blade leading edge. On the casing wall in the impeller, a extreamly large separarion region is formed not only by the tip leakage flow, but by effects of high stagger and low solidity.View full abstractDownload PDF (11645K) -
Effects of Bare Ratio and Outlet Angle of Scroll CasingMakoto HATAKEYAMA, Yoshio KODAMA, Souichi SASAKI, Hidechito HAYASHI, K ...2002 Volume 30 Issue 2 Pages 91-98
Published: February 10, 2002
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSCharacteristics of the aerodynamics and the noise of dual-cascade centrifugal fan have been experimentally investigated with respect to the effects of the bare ratio and the outlet angle of scroll casing. It was shown that the performance of the fans became best when the bare ratio was around between 9% to 25%, then the characterisitics of the dualcascade centrifugal fan were superior to that of the single-cascade centrifugal fan. The former was little influenced by the different bare ratio and the fans were able to be widely designed in comparison with the latter, the both characterisitics were improved when the outlet angle was 20 degrees.View full abstractDownload PDF (4600K) -
Masato EGUCHI, Yoshiyuki MARUTA, Akira GOTO2002 Volume 30 Issue 2 Pages 99-108
Published: February 10, 2002
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSMeasurement system of fluid reaction forces generated on annular pressure seals and bearings was developed, and which was applied active magnetic bearings as shaker and force detector as well as bearing. And from advantages of magnetic bearings, this system can measure exactly restoring force and damping force acting on rotor through fluid film under complete non-contact condition. Moreover, it is possible to measure under high pressure and high rotating speed by it's design specifications.
Leakage velocity through narrow clearance of seal is important for pump's efficiency. And it's necessary for designers of turbo-machine to consider dynamics of fluid film in order to avoid vibration trouble. Cavity tone occurred in pump adopted grooved seals is one of noise phenomena that must clear it's mechanism of occurrence. Therefore, an object of this study is to investigate these properties in order to update the design method for various types of seals.View full abstractDownload PDF (8892K) -
Masashi IKEZAWA, Tuneya SUGIYA, Hiroshi SATOH, Akira INAGAKI2002 Volume 30 Issue 2 Pages 109-114
Published: February 10, 2002
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSIn a flow rate measurement of large capacity pumps, measuring system like ultrasonic flow meter is used as usual. However, at the pumping stations, the measurement with good accuracy can not be expected owing to the lack of straight part of discharge pipe, etc. Considering such situation, we took notice of the water level of surge-tank which act as the buffer of pressure fluctuation in the discharge pipe. First we identified the loss coefficient of discharge line by measuring the transitional fluctuation of water level in the surge-tank, at the moment of stopping pump from stationary operation, and consequently to know the flow rate only by measuring the difference between the level of river and surge-tank. In this paper, we described the method of deriving the formulation and the results of model test that were carried out to validate the above method.View full abstractDownload PDF (3328K) -
[in Japanese], [in Japanese]2002 Volume 30 Issue 2 Pages 115-119
Published: February 10, 2002
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSDownload PDF (12862K)
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