CFD Analysis of Water Droplet Behavior in Axial Flow Compressor

Abstract

A numerical model is developed to characterize erosion caused by water droplets impinging against rotor blades at the first stage of an axial flow compressor. Analyses assume a gas turbine operating with an inlet fogging system. The change in the water droplet size attributable to break-up and evaporation during flight is considered. Numerical calculations are executed using a commercial code in a two-dimensional computational domain including an inlet guide vane, rotor, and stator. The calculated erosion depth shows good agreement with that obtained from empirical correlation in the case without a break-up model. Results show that the break-up occurs over a certain rotor speed, leading to marked reduction of the erosion depth. The choice of the droplet critical Weber number determines the rotor velocity which maximizes the erosion depth. Secondary droplets discharged from the trailing edge of IGV (Inlet Guide Vane) affect erosion more than primary droplets, although their mass flow is smaller.