Turbomachinery
Online ISSN : 1880-2338
Print ISSN : 0385-8839
ISSN-L : 0385-8839
Volume 42, Issue 12
Displaying 1-4 of 4 articles from this issue
Technical papers
  • (Part 3 : Features of Power Systems with Dual Pressure Radial Turbines))
    Hirotaka HIGASHIMORI, SUMIDA SUMIDA
    2014 Volume 42 Issue 12 Pages 757-766
    Published: 2014
    Released on J-STAGE: December 09, 2017
    JOURNAL FREE ACCESS
    Features of power generation systems with “the Dual Pressure Radial Turbine” utilizing intermediate and low temperature waste heat and geothermal energies are shown. The turbine with a single radial turbine wheel can be applied to each of the power generation systems consist of two temperature heat sources and two pressure cycles. And also it can be applied to power generation systems consist of a single heat source and two pressure cycles. In the former applications, two different temperature heat sources such as waste gas and jacket water of reciprocating engines can be used to power generation using the turbine with a single radial turbine. In the latter applications, the output power of power generation systems par unit heat source flow rate is about 14% to 24% larger than conventional single pressure power generation cycles, when temperature of hot water as heat sources is 125°C to 85°C respectively. The dual pressure turbines have less leakage portion and less axial thrust comparing with conventional turbines with two turbine wheels. “The Dual Pressure Radial Turbine” is hopefully applied to actual power generation systems.
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  • Kosuke TAKAHASHI, Daisuke ARAI, Kazuaki INABA, Kikuo KISHIMOTO, Hiroak ...
    Article type: Technical papers
    2014 Volume 42 Issue 12 Pages 767-776
    Published: 2014
    Released on J-STAGE: December 09, 2017
    JOURNAL FREE ACCESS
    Structural repair by polymer coating has been recently attracted attention to pumps in water plants because of its simplicity. The performance of coating material is simply evaluated by cavitation resistance, but it should be considered under loading condition for application to existing structures. In this study, damage of coating material due to cavitation is observed with various loading conditions. Epoxy resin is selected as coating material on aluminum base. First, tensile and shear tests of the coating material is conducted with different way of coating angles to obtain fracture stresses. Second, a conventional cavitation erosion test is modified using a tensile jig developed to conduct a tension-cavitation test. As a result, the tensioncavitation test resulted in much severer damage in short time than conventional cavitation erosion test even though the stress on the coating material is more than 10 times smaller than the fracture stresses.
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  • Toru SHIGEMITSU, Chihiro TANAKA, Junichiro FUKUTOMI
    Article type: Technical papers
    2014 Volume 42 Issue 12 Pages 777-784
    Published: 2014
    Released on J-STAGE: December 09, 2017
    JOURNAL FREE ACCESS
    Small hydropower generation is one of important alternative energy, and potential of small hydropower is great. Efficiency of small hydro turbines is lower than that of large one, and these small hydro turbine's common problems are out of operation by foreign materials. Then, there are demands for small hydro turbines to keep high performance and wide flow passage. Therefore, we adopted contra-rotating rotors, which can be expected to achieve high performance and enable to use low-solidity rotors with wide flow passage, in order to accomplish high performance and stable operation. In this research, performance of the contra-rotating small hydro turbine with 60 mm casing diameter was investigated by an experiment and numerical analysis. Efficiency of the contra-rotating small hydro turbine was high in pico-hydro turbine and high efficiency could be kept in wide flow rate range, however the performance of a rear rotor decreased significantly at partial flow rate. Then, internal flow condition, which was difficult to measure experimentally, was investigated by the numerical flow analysis. Then, a relation between the performance and internal flow condition was considered by the numerical analysis result.
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  • Soichi SASAKI, Ikki TORISE, Hiroaki MURAKAMI
    Article type: Technical papers
    2014 Volume 42 Issue 12 Pages 785-792
    Published: 2014
    Released on J-STAGE: December 09, 2017
    JOURNAL FREE ACCESS
    The objective of this study is to clarify influence of blade tip vortex on aerodynamic noise of a propeller fan operated at the vicinity of maximum efficiency point. The influence of the internal flow on the aerodynamic noise is discussed based on the parameter of axial direction relative position. When the position was 20 mm, the periodical noise at 200 Hz became large. The periodical noise became one of the major factors for increasing the fan noise. The periodical noise was generated by the interaction between the blade tip vortex and the partition of the fan. We clarified that when the wake of the impeller formed the flow regime of the low specific speed type impeller, the periodical aerodynamic noise was generated.
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