Prediction of Evaporative Effects Within the Blading of an Industrial Axial Compressor

Abstract

The results of a compressor flow-analysis code calibration study for estimating the effects of water evaporation within the blade rows of industrial axial compressors are presented. In this study, a mean-line code was chosen for the calibration tool due to its accepted use during preliminary design studies, at which time during the compressor design process one would logically consider power augmentation through wet compression. The calibrated code features a nonequilibrium thermodynamic single-droplet evaporation model augmented with an empirical splashing model, which, as input, uses measurements of droplet spectra data taken on water injection nozzles in an intake rig configured with realistic length scales. In addition, a wetted-airfoil-surface flow-angle deviation model is applied to predict changes in compressor stage characteristics, which, in turn, affect the inlet mass flow of the compressor. The test vehicle for calibration was a 50 Hz Alstom industrial gas turbine. Once calibrated, the code was successfully utilized to predict wet-compression effects for three additional like-family Alstom gas turbines operating at constant speed while under full load. The effects modeled by the code include bleed supply pressure suck-down and bleed temperature cool-down effects, as well as compressor inlet mass flow and power consumption effects.