Leakage flow characteristic of radial inflow turbine adopted in CAES system: Review on progress

Compressed Air Energy Storage (CAES) System is an important power output component of the energy storage technology. Radial inflow turbine is the main power output device in CAES system, it is operated at extraordinary operation condition (inlet pressure ≥ 75 bar and inlet temperature < 500 K) which is different from gas turbine and other turbomachinery. Therefore, clearance existing in the CAES radial inflow turbine will result in special leakage flow characteristic and higher flow loss, which decreases the aerodynamic performance and the economic efficiency of the CAES system. However, most of researches for CAES radial inflow turbine mainly focus on the performance prediction of CAES system with one-dimensional model, the detailed leakage flow loss mechanism based on three-dimensional analysis, which significantly influences the flow structure and efficiency, are still needed to be further conducted. In present study, the progress on leakage flow characteristic in the CAES radial inflow turbine is reviewed. The effects of tip clearance, case-shroud clearance and back cavity of rotors are summarized, the leakage flow mechanism and loss reduction method are also analyzed and discussed. Suggestions for the future work on leakage flow of CAES radial inflow turbine are also proposed. The present review can provide a guide for new design and optimization of the radial inflow turbine adopted in CAES system.