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Volume 29, Issue 12
Displaying 1-6 of 6 articles from this issue
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An Effective Solution for Oil and Gas ProductionMasaru IHARA, Kazuaki MIYATA, Masato YAMASHITA2001 Volume 29 Issue 12 Pages 705-711
Published: December 10, 2001
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSDownload PDF (8860K) -
Hideaki TAMAKI, Hiroshi YAMAGUTHIA, Takeshi AIZAWA2001 Volume 29 Issue 12 Pages 712-718
Published: December 10, 2001
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSThe effect of a diffuser vane setting angle on the performance of a centrifugal compressor was investigated. 7 vaned diffusers were tested with the same impeller. In order to remove the effect of the throat geometry, all the diffusers were designed to have the same throat area. The test results and the calculation with a simple one-dimensional model showed that the diffuser vane setting angle was one of the most important parameters to predominate the vaned diffuser. The calculation also showed that it would be possible to chose the several vane setting angles without any change of the compressor efficiency at a certain flow rate by the selection of the appropriate area ratios.View full abstractDownload PDF (2293K) -
Choon-Man JANG, Masato FURUKAWA, Masahiro INOUE2001 Volume 29 Issue 12 Pages 719-729
Published: December 10, 2001
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSThe three-dimensional vortical flow structure in a propeller fan with a shroud covering only the rear region of its rotor tip has been investigated by a Reynolds-averaged Navier-Stokes (RANS) flow simulation.The vortical flow structure is identified by a semi-analytical method based on the critical point analysis and colored by a normalized helicity to analyze the nature of vortices. Three types of vortex structure are found near the rotor tip region: a tip vortex, a leading edge separation vortex, and a tip leakage vortex. The tip vortex, which has the largest structure, grows in the tangential direction even at the design operating condition. The interaction between the tip vortex and the blade pressure surface causes the breakdown of the tip vortex. The breakdown forms a bubble-like recirculation region in the tip vortex near the pressure surface. The recirculation region causes an expansion of the tip vortex, thus leading to the large blockage effect on the through flow.View full abstractDownload PDF (13370K) -
Michihiro NISHI, Kouichi YOSHIDA, Masami MATSUNAGA, Yoshitaka KIKIRIKU ...2001 Volume 29 Issue 12 Pages 730-735
Published: December 10, 2001
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSThis paper presents a basic study on pressure loss of a cylindrical intake (inner diameter=2R=200mm, wall thickness=t=25 or 50mm), where measurements were made under the conditions of Reynolds number being (1.0-1.4)×105 and external/internal velocity ratio being 0-0.29 for each of the following three intake-lips:(a) quarter round lip (Type A: t/R=0.25), (b) semi-circular lip (Type B: t/R=0.25). and (c) semi-circular lip (Type C: t/R=0.50). From the experimental results, it is clarified that the curvature of intake inner-wall is a key factor to secure the good fl uid-dynamic performance. Each pressure loss was correlated with the wall pressure distribution and the separation region. The latter was favorably v isualized with the distribution of back-flow fraction measured with a split film probe. Further, it is demonstrated that the reduction of pressure loss was achieved by installation of a backward-facing-ramp type bar in the separation region of Type B intake, which is regarded as a new method for separation control.View full abstractDownload PDF (4330K) -
Tadashi TAGUCHI, Narumi UMEDA, Kotaro TEZUKA, Yasuyuki ENOMOTO2001 Volume 29 Issue 12 Pages 736-744
Published: December 10, 2001
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSWe have been investigating several technical measures to improve hydraulic performance of pump-turbines which are to be installed into pumped storage power stations with a wide operating-head-range. A splitter runner, which has long blades. and short blades in circumferentially alternate positions, can be one of the means for achieving this aim. In this paper, characteristic flow-patterns in the splitter runner and appropriate design methods based on them are discussed. As far as flowpattern is concerned, influence of circumferential pitch between a long blade and a short blade is focused on especially. Through flow analyses for some runners, it has become clear that making the short blade move to its pressure side direction enhances turbine operation performance. After optimization of the runner by flow analysis at the design stage, model tests were conducted to verify its hydraulic performance and to optimize it further. Finally, the developed splitter runners for low/high specific-speed pump-turbines proved to demonstrate better hydraulic performance and smaller pressure fluctuation compared to conventional runners.View full abstractDownload PDF (5549K) -
Linhu ZHAO, Junichi KUROKAWA, Jun MATSUI, Hiroshi IMAMURA, Tadashi TSU ...2001 Volume 29 Issue 12 Pages 745-754
Published: December 10, 2001
Released on J-STAGE: July 11, 2011
JOURNAL FREE ACCESSA conventional hydropower system for variable head is not suitable for micro-hydropower because of relatively high cost. In this study, two variable speed micro-hydro power systems that consist of low-cost commercial power electronic elements are developed for variable head micro-hydropower. One is composed of a synchronous generator and an electronic load governor for the purpose of applying to an isolated operation, and the other is composed of an induction generator for the purpose of connecting to power system. The experimental results showed that turbine performance and total system efficiency at off-design heads are improved much by using these systems.The performance characteristics of a simplified lowhead cross-flow turbine are also determined experimentally in the wide range of head.View full abstractDownload PDF (1195K)
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