CFD aerodynamic investigation of air-water trajectories on rotor-stator blade of an axial compressor

In multistage axial-flow compressors, the droplet size distribution of the injected fluid depends upon the entry conditions. In general, droplet trajectory prediction is important for particulate laden flow turbomachinery as it helps to understand the pitting and the cutting of the blade leading and trailing edges as well as to improve the design of blade passages. An investigation was carried out using CFX-TASCflow on the aerodynamics of an axial-flow compressor designed for operation with air while operating with an air-fluid droplet mixture during field operation. In this study, a 3D rotor-stator blade with constant rotor rotating speeds was simulated. Droplet trajectories in rotor-stator were predicted in connection with full 3D air flow field solved by k-omega SST method. The test matrix involved different initial droplet diameters with constant rotor shaft rotation. The liquid used was water. The main objective of the investigation is to provide a physically realistic model describing the movement of liquid phase in an industrial axial compressor. In order to achieve this objective, CFD simulations were developed for predicting the water particle trajectories inside an industrial axial compressor, the rate of evaporation of water droplets on axial compressor blades by inertial impaction, turbulent diffusion, pressure and temperature increments. Simulation of water droplet trajectories and evaporation of water droplet content in designed gas turbine engine were also undertaken. The velocities and trajectories of the droplets, on the blades and the amount of water evaporated were investigated. The results show that the initial conditions of the droplets (velocity and size) have substantial influence on the flow pattern.