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Unstable Head-Flow Characteristic Generation Mechanism of a Low Specific Speed Mixed Flow pump

Journal of Thermal Science 2006年第2期15卷 115-120,144页

作者： Masahiro MIYABE Hideaki MAEDA Isamu UMEKI Yoshinori JITTANI Department R & D torishima pump mfg. co. Ltd. 1-1-8 Miyata-cho Takatsuki-shi Osaka 569-8660 JAPAN

This paper treats the flow instabilities in a mixed flow pump with a vaned diffuser. Test pump has a positive slope of a head-flow performance curve at 65% flow rate of BEP (Best Efficiency Point) because of a rotating stall. Dynamic Particle Image Velocimetry (PIV) and pressure fluctuation measurements are used for investigating the propagation mechanism of a rotating stall. It was found that unstable performance was caused by periodical large scale abrupt backflow generated from the vaned diffuser to the outlet of impeller. Further, the relation between the static pressure at the inlet of diffuser vane and the internal flow co.dition was clarified. From these experimental results, in order to improve the positive slope of a head-flow performance curve, to suppress the growth of strong vortex toward the inlet of diffuser vane was proved to be a key point.

关键词： mixed flow pump vaned diffuser flow instabilities rotating stall dynamic PIV

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Flow Structure Around the Intake of a Vertical pump

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Journal of Thermal Science 2006年第2期15卷 121-125页

作者： Akihiro WADA Research and Development Dept. torishima pump mfg. co. Ltd. 1-1-8 Miyata-cho Takatsuki Osaka 569-8660 Japan

The flow structure around the intake of a vertical pump is investigated experimentally and numerically in order to obtain a guideline in designing the optimum shape of the intake of vertical pumps, in which their installation area is demanded to be minimum without losing the high performance. We co.centrate our attention on the expansion ratio of the intake as a representative characteristic of the shape of the pumps and investigate the effect of the expansion ratio on pump performance. It is co.cluded that the optimum expansion ratio ranges in 1.1-1.2 if we take into co.sideration that the area needed for the installation of the pump should be minimum.

关键词： vertical pump shape of intake flow structure around the intake

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Aco.stic Absorption Characteristics of Perforated Thin Plate with Air Jets and Cavity

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Open Journal of Fluid Dynamics 2015年第1期5卷 1-9页

作者： Hiromitsu Hamakawa Hiroki Matsuoka Taiki Yamai Kenta Asakura Toru Otsuru Reiji Tomiku Eru Kurihara Hidechito Hayashi Eiichi Nishida Department of Mechanical Engineering Oita University Oita Japan Graduate School Master’s Program of Engineering Oita University Oita Japan torishima pump mfg. co. Ltd Takatsuki-shi Osaka Japan Department of Architecture Oita University Oita Japan Department of Mechanical Engineering Nagasaki University Nagasaki Japan Department of Mechanical Systems Engineering Shonan Institute of Technology Fujisawa-shi Kanagawa Japan

The present paper focuses on the effect of air jets through a perforated thin plate on the characteristics of an aco.stic absorption co.fficient. We measured the flow rate, internal pressure, aco.stic pressure, and transfer function by using an improved aco.stic impedance tube. The normal incidence absorption co.fficient was calculated from the measured transfer function using transfer function methods. As a result, the frequency characteristics of the aco.stic absorption co.fficient against the frequency showed a maximum value at the local frequency. The peak frequency of the aco.stic absorption co.fficient depended on the thickness of the background air space and the thickness of the perforated plate. As the flow rate increased through the micropores, the peak level of the aco.stic absorption co.fficient also increased until a flow rate of 80?l /min. As the flow rate further increased, the peak level of the aco.stic absorption co.fficient decreased and that of the high frequency band increased.

关键词： Aco.stic Absorption co.fficient Perforated Plate Cavity Micropores Air Jets Aco.stic Impedance Tube

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