Characteristics of inlet guide vane adjustment of multi-stage axial compressor in compressed air energy storage system

Abstract

The compressor in compressed air energy storage (CAES) system needs to balance continuous variable conditions and high-efficiency operation. The adjustment of inlet guide vanes (IGV) can effectively expand the stable working range of the compressor and improve the variable condition performance. The purpose of this study is to provide a reference for the efficient and variable condition operation of axial compressors in CAES system. This study takes a five-stage axial compressor in a specific CAES system as the research object, and uses numerical method to investigate the IGV adjustment characteristics of the compressor. Firstly, the overall performance variation of the compressor is analyzed. It is found that the IGV adjustment has a significant effect on expanding the stability range of the compressor, increasing it from 11.6 % to 33.4 %. The optimal adjustment curve of the IGV serves as a reference for achieving high-efficiency operation of the energy storage compressor. Secondly, the variations of the stage static pressure ratio, stage degree of reaction, rotor diffusion factor, rotor inlet airflow angle, relative Mach number on S1 surface of the first 1.5 stages, and the limit streamlines on blade suction surfaces are analyzed for different IGV angles. It is observed that minor IGV adjustment can regulate the distribution of aerodynamic parameters and internal flow of the first stage without significantly affecting the distribution of aerodynamic parameters in the subsequent stages. However, significant changes in the aerodynamic parameters of all stages occur when large adjustments are made to the IGV. Finally, the distribution characteristics of losses on the blade suction surface, meridional flow channel, and IGV for different angles are studied. When the IGV are adjusted from −10° to +35°, the high-entropy region on the IGV suction surface gradually increases, while the high-entropy region on the leading edge of the first-stage rotors decreases. The changes in aerodynamic parameters at each stage during large angle adjustments exacerbate the deterioration of internal flow, leading to a significant increase in the high-entropy region in the meridional flow channel. The loss ratio fitting curve provides a quantitative basis for evaluating the IGV losses at different adjustment angles.