TY - JOUR
T1 - The relation between internal flow and loss mechanism of unshrouded runners
AU - Nagata, Shunsuke
AU - Irie, Tatsuya
AU - Miyagawa, Kazuyoshi
N1 - Publisher Copyright:
© Published under licence by IOP Publishing Ltd.
PY - 2022/5/6
Y1 - 2022/5/6
N2 - High efficiency, low-cost, and reliable hydraulic turbines are in high demand for hydroelectric power generation, especially in medium and small-scale power plants. The authors' laboratory has been developing unshrouded, i.e., band-opened runners of turbines to meet the demand. Those runners feature highly efficient performance and less expensive manufacturing costs produced by cutting, not by casting. For the sake of developing further improved unshrouded runners, it is necessary to understand their loss mechanism in detail. Therefore, in this study, the internal flow and the loss mechanism are investigated experimentally and computationally, with two different specific speed hydro turbine runners. First, Euler's theoretical head on each runner is discussed to identify if they are influenced by the distinct specific speed. It demonstrated that the low specific speed turbine consumes greater potential energy in centrifugal force. Secondary, the loss mechanism in the unshrouded runners is investigated. The result showed that the dominant loss is caused by a tip leakage vortex developed by the collision of a leakage flow at the tip clearance and a secondary flow.
AB - High efficiency, low-cost, and reliable hydraulic turbines are in high demand for hydroelectric power generation, especially in medium and small-scale power plants. The authors' laboratory has been developing unshrouded, i.e., band-opened runners of turbines to meet the demand. Those runners feature highly efficient performance and less expensive manufacturing costs produced by cutting, not by casting. For the sake of developing further improved unshrouded runners, it is necessary to understand their loss mechanism in detail. Therefore, in this study, the internal flow and the loss mechanism are investigated experimentally and computationally, with two different specific speed hydro turbine runners. First, Euler's theoretical head on each runner is discussed to identify if they are influenced by the distinct specific speed. It demonstrated that the low specific speed turbine consumes greater potential energy in centrifugal force. Secondary, the loss mechanism in the unshrouded runners is investigated. The result showed that the dominant loss is caused by a tip leakage vortex developed by the collision of a leakage flow at the tip clearance and a secondary flow.
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U2 - 10.1088/1742-6596/2217/1/012064
DO - 10.1088/1742-6596/2217/1/012064
M3 - Conference article
AN - SCOPUS:85130284780
SN - 1742-6588
VL - 2217
JO - Journal of Physics: Conference Series
JF - Journal of Physics: Conference Series
IS - 1
M1 - 012064
T2 - 16th Asian International Conference on Fluid Machinery, AICFM 2021
Y2 - 13 September 2021 through 15 September 2021
ER -