Energy Storage Science and Technology ›› 2021, Vol. 10 ›› Issue (5): 1524-1535.doi: 10.19799/j.cnki.2095-4239.2021.0338

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Optimal design and flow loss reduction mechanism of bowed guide vane in a CAES axial flow turbine

Xing WANG1,2(), Wen LI1,2, Yangli ZHU1,2, Zhitao ZUO3, Haisheng CHEN1,2,4()   

  1. 1.Institute of Engineering Thermophysics, Chinese Academy of Science, Beijing 100190, China
    2.University of Chinese Academy of Sciences, Beijing 100049, China
    3.National Energy Large Scale Physical Energy Storage Technologies R&D Center of Bijie High-tech Industrial Development Zone, Bijie 551712, Guizhou, China
    4.Nanjing Institute of Future Energy System, Institute of Engineering Thermophysics, Chinese Academy of Science, Nanjing 211135, Jiangsu, China
  • Received:2021-07-13 Revised:2021-07-25 Online:2021-09-05 Published:2021-09-08

Abstract:

Axial-flow turbines adopted in compressed-air energy storage (CAES) systems are characterized by higher operating pressure, vane with lower aspect ratio, and obvious end-wall secondary flow loss. To increase the efficiency, herein, bowed design is introduced into the vane, and the system is optimized. Moreover, the flow-loss control mechanism of optimal bowed vanes is investigated. The results show an optimal bending angle for maximum isentropic efficiency under each bending height. With an increase in the bending height, the optimal bending angle gradually decreases. The mass flow rate of the axial-flow turbine decreases first and then increases with an increase in the bending angle; a minimum mass flow rate is observed close to the bending angle of 7°. The optimal design results show that when the bending angle and relative bending height are 12.26° and 0.31°, respectively, the isentropic efficiency can be increased by 0.77%, and the mass flow rate increases by only 0.1 kg/s. Although the optimal bowed structure has some negative effects on its own flow field in the vane, it still reduces the inlet flow angle of the rotor blade near the hub, eliminates the stagnation saddle point in front of the rotor-blade leading edge, and limits the influence range of horseshoe vortex and interaction with the end-wall secondary flow. Moreover, the saddle point in the tip leading-edge region moves downstream; limits the influence range of the horseshoe vortex near the suction surface; delays the generation of tip clearance leakage flow, which interacts with the tip clearance upper-passage vortex; and flow loss is reduced.

Key words: compressed air energy storage, axial turbine, bowed stator, optimiztion, flow mechanism

CLC Number: