Investigation of Different Rotational Speed Characteristics of Multistage Axial Compressor in CAES System

Abstract

An axial compressor has high efficiency under design conditions, but its stable working range is narrow. Adjusting the rotational speed can effectively expand the stable working range. In this paper, a five-stage axial compressor for a specific compressed air energy storage (CAES) system is taken as the research object, and different rotational speed (DRS) characteristics are studied with NUMECA software. Firstly, the influence of DRS on overall aerodynamic performance is explored, and the working flow range of the compressor is increased from 11.5% to 54.0%. Secondly, the effect of DRS on inlet parameters of the first stage rotor is analyzed, and the reasonable distribution of inlet parameters is obtained. Thirdly, the changing law of the internal flow is investigated at DRS. The corner separation is gradually enhanced when the rotational speed increases, and the leakage flow velocity at the rotor tip gradually improves. Finally, the loss distribution of tip clearance is researched. The result shows that the loss distribution increases significantly in both circumferential and spanwise directions when the speed increases. This work aims to provide a reference for the stable and efficient operation of axial compressors in CAES systems under the wide working range.