Turbomachinery
Online ISSN : 1880-2338
Print ISSN : 0385-8839
ISSN-L : 0385-8839
Volume 52, Issue 6
Displaying 1-5 of 5 articles from this issue
Technical papers
  • Katsuhiko KASHIHARA, Yuka YAMASHITA, Kunihiko ISHIHARA
    Article type: Technical papers
    2024Volume 52Issue 6 Pages 323-333
    Published: 2024
    Released on J-STAGE: May 09, 2025
    JOURNAL FREE ACCESS

    Ducts are widely used in various industry fields. For example, a high-power suction truck has a complex piping system which starts from a root blower to a final exit while repeating bend. The root blower generates a large pulsation and makes resonance with the piping system. In order to avoid the resonance, it is necessary to know the natural acoustic frequencies of the piping system. Especially, when loading space is limited, we want to change the natural acoustic frequencies without changing the length, or not to change the natural acoustic frequencies with changing the cross sectional area. Then in this paper, the relation between natural acoustic frequency and the position where the cross sectional area changes is discussed and we became able to calculate the variations in natural acoustic frequencies for tubes with different diameters.

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  • Yuka IGA, Takashi YOKOI, Shuichi MORIYA, Junnosuke OKAJIMA, Motohiko N ...
    Article type: Technical papers
    2024Volume 52Issue 6 Pages 334-343
    Published: 2024
    Released on J-STAGE: May 09, 2025
    JOURNAL FREE ACCESS

    In this study, cavitation instabilities arising in a centrifugal pump were investigated through visualization of the cavity behavior and the external noise measurement by a microphone. The visualized image was analyzed by image processing and the frequency of the cavitation instabilities was identified. From the measured external noise, it was found that a frequency component is included in the external noise, the frequency corresponds to a whirling vibration of the pump shaft accompanied by a rotating cavitation. Additionally, is was shown that the frequency component which corresponds to a frequency of unsteady cavitation in the rotating cavitation does not appear in the external noise.

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  • Toru SHIGEMITSU, Yuya HIRAISHI, Takuji HOSOTANI
    Article type: Technical papers
    2024Volume 52Issue 6 Pages 344-354
    Published: 2024
    Released on J-STAGE: May 09, 2025
    JOURNAL FREE ACCESS

    Researches of in-line small hydroturbines smaller than 100 mm diameter are less conducted and a small hydroturbine that can be used for pipe lines of agricultural water which is small as 2 inches diameter, is not exist. Therefore, we started the research and development of the small hydroturbine based on our basic research of the contra-rotating small hydroturbine. Field tests to measure the theoretical power and observe foreign materials of the pipe line in Tokushima Prefecture were carried out. The numerical analysis with the simple model of 50 mm diameter rotor was conducted to check the possibility to apply the contra-rotating small hydroturbine to the pipe line and the performance and flow conditions in wide flow rates were clarified. After that, the small hydroturbine system having 49 mm diameter rotor for the field test was established and the power generation test was conducted at our laboratory. Our research and development process of the 49 mm diameter contra-rotating small hydroturbine is shown in this paper.

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  • Hiroyuki NAGAI, Toshihiro TSUTSUI, Keiichiro TAKATO
    Article type: Technical papers
    2024Volume 52Issue 6 Pages 355-366
    Published: 2024
    Released on J-STAGE: May 09, 2025
    JOURNAL FREE ACCESS

    The authors are developing a new mechanism using an open typed waterwheel set on a catamaran-like floating body to recover the surface-tidal current energy. Many knowledges on the behavior of a waterwheel installed in a pure channel have been already presented. On the other hand, as the flow around such a floating body is mixed with the external and the internal one, the behavior of the waterwheel installed on it has not been well-known yet. In this paper, we present the collecting effect with the width change of cross-sectional area in the shallow channel constructed by the floating body. And in the circulating water tank the enhancement of the waterwheel velocity is extracted by using cantilevered-typed velocimeter and undershot waterwheel model with 8 flat plates which made using a 3D printer.

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  • Shinichiro EJIRI
    Article type: Technical papers
    2024Volume 52Issue 6 Pages 367-373
    Published: 2024
    Released on J-STAGE: May 09, 2025
    JOURNAL FREE ACCESS

    The purpose of this study is to investigate the fundamentals of multi-materialization of impellers by a manufacturing process using wire arc metal additive manufacturing (WAAM). In this study, first, tensile specimen of nickel based alloy Inconel 718 were fabricated using WAAM, then mechanical properties were evaluated. Next, a multi-material axial-flow impeller was manufactured. The near blade shape of a nickel base alloy Inconel 718 made by WAAM on a stainless steel SUS 304 round bar base material, after that finishing the shape by machining. The manufactured axial-flow impeller was installed as an inducer on an industrial centrifugal pump to confirm its function as the inducer. These results indicate that it is possible to realize multi-material impellers using WAAM.

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