Theoretical and experimental study on effects of wet compression on centrifugal compressor performance

Through the internal cooling from evaporation of tiny water droplets during the compression process, wet compression can effectively augment the net power output of gas turbine under high ambient temperature condition. In this paper, effects of wet compression on compressor performance were theoretically and experimentally investigated on one of stages of a multistage centrifugal compressor and a new performance correction model for wet compression was proposed. This model is based on corrected similarity criterion and couples with equivalent gas properties of wet compression, droplet evaporation model and droplet dynamics loss. The results show that wet compression can increase pressure ratio and efficiency and reduce specific compression work at same pressure ratio. The effect enhances with the increase of water injection ratio and the decrease of droplet average diameter. The essence of influence on performance is the variation of equivalent isentropic exponent. For this stage, maximum pressure ratio and peak efficiency increase by 4.25% and 0.71% respectively with a water injection ratio of 2% and a droplet average diameter of 10 μm.