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Volume 31, Issue 2
Displaying 1-9 of 9 articles from this issue
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Morihito INAGAKI, Mitsuhiro ISHIGURO2003 Volume 31 Issue 2 Pages 65-71
Published: February 10, 2003
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSDownload PDF (2594K) -
Shoji YOSHIMURA2003 Volume 31 Issue 2 Pages 72-76
Published: February 10, 2003
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSDownload PDF (7129K) -
Hidenobu SHOJI, Akira MANABE, Toshikazu KATAOKA2003 Volume 31 Issue 2 Pages 77-83
Published: February 10, 2003
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSTo clarify the effect of inlet flow condition on the performance of the mixed-flowpump at partial flow rate, experiments were executed under the condition of different gaps between the bell mouth and the bottom wall, and with the baffle for interrupting the recirculating flow in front of the bell mouth. Velocity and pressure distributions were measured at inlet and outlet of the impeller. Results showed that inlet reverse flow was formed less than about 60% of design flow rate and developed large scale recirculating flow less than about 40% flow rate. Pump head and shaft power near shut off condition were mainly determined by the flow pattern inside and outside of the bell mouth.View full abstractDownload PDF (713K) -
Tom SHIGEMITSU, Akinori FURUKAWA, Kusuo OKUMA, Satoshi WATANABE2003 Volume 31 Issue 2 Pages 84-90
Published: February 10, 2003
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSA contra-rotating rotor has been applied to an axial flow pump against the demand for higher specific speed. It was validated from the previous experiment with contra-rotating rotors that a rotational speed controlling of the rear rotor was capable of improving the efficiency at off-design point, though the specified pump head and maximum efficiency were not satisfied at design point. It was also concluded that the rear rotor design was important for further improvement of pump performance. In order to obtain the useful data for rear rotor design the rear rotor was redesigned under the condition of wider fl ow passage area. The new rotor has lower stagger angle, larger blade number and lower solidity than the previous one. In the present paper, experimental data for the present and the previous rotors under the same front rotor are compared in pump characteristics. Appropriate design parameters are discussed to obtain higher performance of rear rotor with help of measured results of radial distributions of flow in up-and downstream sections of rear rotor and blade to blade distributions of casing wall static pressures.View full abstractDownload PDF (908K) -
Takeharu KOBAYASHI, Tsunehisa UCHIYAMA, Risaburo OBA2003 Volume 31 Issue 2 Pages 91-96
Published: February 10, 2003
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSIn order to clarify the wall effects upon Recso often observed in valve experiments, we take up a simple flow around a circular cylinder of diameter d set within a two-dimensional channel of hight h, when the blockage factor B=d/h=0.75. And systematical measurements are made for the upstream-and the downstream-velocity distribution around the cylinder, by means of an PIV-technique, resulting in time-averaged nondimensional velocity change Δu/u1, in proportion to the drag coefficient with respect to Reynolds number Re. In the present case of extremely high B-Rec is unexpectedly reduced about one figure than the small B-counterparts.View full abstractDownload PDF (886K) -
Koichi MASUBUCHI, Takeharu KOBAYASHI, Tsunehisa UCHIYAMA, Risaburo OBA2003 Volume 31 Issue 2 Pages 97-103
Published: February 10, 2003
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSWhen the wall effects as well as the blockage factors B is small, our high-speed observations of pseudo-supercavitating cavities clearly showed such an important fact as the flow shifts comparatively stably between the subcavitating region and the transient one, and between the transient one and the supercavitating one. In this paper, in order to clarify the flow shift aspects in a two-dimensional channel of extremely high wall effects, we carefully observe high-speed cavity behavior for the most practical case when B is large such as in a supercavitating cascade, showing the similar results as the flow shifts are stable, even in this case.View full abstractDownload PDF (9198K) -
Takuji NAGAYOSHI, Akihiko MINATO, Ichiro HARADA, Masahiro MASE2003 Volume 31 Issue 2 Pages 104-110
Published: February 10, 2003
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSA prediction method of air discharge characteristics during the self-priming stage has been developed for siphon pipes of pump stations on the basis of air entrainment and transport correlations coupled with the quasi-steady-state equation of an open channel. Duration times required for siphon completion of siphon discharge pipes, taking account of pipe size and geometry, water levels and pump characteristics can be predicted. The developed method was applied to the siphon completion time prediction for siphon pipes with various sizes and geometries, including a full-scale circular pipe and a 1/15-sclae rectangular conduit. Measured and predicted siphon completion times agreed within about 50% devlations, and there were no significant bias errors depending on pipe sizes or geometries.View full abstractDownload PDF (1001K) -
Effects on Performance and Noise by Improving Outlet Angle of ImpellerToshiyuki HIRANO, Gaku MINORIKAWA, Shoji SUZUKI, Shimpei MIZUKI2003 Volume 31 Issue 2 Pages 111-116
Published: February 10, 2003
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSRecently, a turbofan with the higher flow rate and the higher pressure than the present one is required for the usage to such a complicated plumbing as a car washing machine. In addition, it is also important to establish the design method for the noise reduction of a turbofan. In this study, the aerodynamic performance of a turbofan including the noise reduction was developed by increasing the outlet angle of the impeller. In order to examine the effects of the improved performance and the noise reduction, both the distribution of relative velocity and its fluctuation in the outlet flow were investigated.View full abstractDownload PDF (646K) -
Tadakazu TANINO, Masahiro INOUE, Yuji OHYA, Takashi KARASUTANI, Hirosh ...2003 Volume 31 Issue 2 Pages 117-123
Published: February 10, 2003
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSThe power output of a diffuser-shrouded wind turbine is enhanced significantly by coupling a brim to the diffuser exit plane. A design and a predicting method for aerodynamic performance have been presented by a simple theory. Rotor blades of a model wind turbine were newly designed for a specified brimmed diffuser by using this simple theory and tested in the wind tunnel to verify the design method. The performance was also tested by changing the number of blades and types of brimmed-diffuser. Comparison between the test results and prediction shows that the simple predicting method demonstrates the effects of the blade number and the brimmed-diffuser in some extent. Further improvement of the performance is sueeested.View full abstractDownload PDF (874K)
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