TY - GEN
T1 - Effect of tip clearance on rotating stall in a mixed-flow pump
AU - Li, Wei
AU - Agarwal, Ramesh K.
AU - Zhou, Ling
AU - Li, Enda
AU - Ji, Leilei
N1 - Funding Information:
The authors would like to acknowledge CFD Lab of the Washington University in St. Louis for their support. This work was sponsored by the National Natural Science Foundation of China (No.51679111, No.51409127 and No.51579118), National Key R&D Program Project (No.2017YFC0403703), PAPD, Key R&D Program Project in Jiangsu Province (No.BE2016319, No.BE2017126), Natural Science Foundation of Jiangsu Province (No.BK20161472, No.BK20160521).
Publisher Copyright:
Copyright © 2019 ASME.
PY - 2019
Y1 - 2019
N2 - The non-uniform disturbance in the circumferential direction is the main cause for the occurrence of rotating stall in turbomachinery. In order to study the effect of tip clearance leakage flow on rotating stall, the mixed-flow pump models with different tip clearances are numerically simulated, and then the energy performance curves and internal flow structures are obtained and compared. The results show that the computed pump efficiency and the internal flow field of the pump from numerical simulation are in good agreement with the experimental results. A saddle region appears in the energy performance curves of the three tip clearances, and with decrease in tip clearance, the head and efficiency of the mixed-flow pump increase and the critical stall point shifts, and the stable operating range of the mixed-flow pump decreases, which indicates that the mixed-flow pump stalls easily for smaller tip clearance. Under the deep stall condition, the influence of the leakage flow in the end wall area increases gradually with decrease in clearance. For small clearance, the leakage flow moves away from the suction surface to some distance to form a number of leakage vortex strips with the mainstream flow and flows over the leading edge of the next blade and then flows downstream into different flow passages, generating backflow and secondary flow separation at the blade inlet, which seriously damages the spatial structure of the inlet flow. This results in the earlier occurrence of stall. With increase in clearance, the leakage vortex develops along the radial direction towards the middle of the flow channel and large flow separation occurs in the downstream channel, which induces deep stall. For 0.8mm clearance, the whole impeller outlet passage is almost blocked by the backflow of the guide vane inlet, and a deep stall is induced.
AB - The non-uniform disturbance in the circumferential direction is the main cause for the occurrence of rotating stall in turbomachinery. In order to study the effect of tip clearance leakage flow on rotating stall, the mixed-flow pump models with different tip clearances are numerically simulated, and then the energy performance curves and internal flow structures are obtained and compared. The results show that the computed pump efficiency and the internal flow field of the pump from numerical simulation are in good agreement with the experimental results. A saddle region appears in the energy performance curves of the three tip clearances, and with decrease in tip clearance, the head and efficiency of the mixed-flow pump increase and the critical stall point shifts, and the stable operating range of the mixed-flow pump decreases, which indicates that the mixed-flow pump stalls easily for smaller tip clearance. Under the deep stall condition, the influence of the leakage flow in the end wall area increases gradually with decrease in clearance. For small clearance, the leakage flow moves away from the suction surface to some distance to form a number of leakage vortex strips with the mainstream flow and flows over the leading edge of the next blade and then flows downstream into different flow passages, generating backflow and secondary flow separation at the blade inlet, which seriously damages the spatial structure of the inlet flow. This results in the earlier occurrence of stall. With increase in clearance, the leakage vortex develops along the radial direction towards the middle of the flow channel and large flow separation occurs in the downstream channel, which induces deep stall. For 0.8mm clearance, the whole impeller outlet passage is almost blocked by the backflow of the guide vane inlet, and a deep stall is induced.
UR - http://www.scopus.com/inward/record.url?scp=85070379732&partnerID=8YFLogxK
U2 - 10.1115/GT2019-90134
DO - 10.1115/GT2019-90134
M3 - Conference contribution
AN - SCOPUS:85070379732
T3 - Proceedings of the ASME Turbo Expo
BT - Turbomachinery
PB - American Society of Mechanical Engineers (ASME)
T2 - ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition, GT 2019
Y2 - 17 June 2019 through 21 June 2019
ER -