A numerical study on the water droplet erosion of blade surfaces

Wet compression systems are installed in a gas turbine engine to increase the net power output. One major drawback in wet compression system is the erosion of compressor blades due to fine water droplets hitting the surface. In the present numerical work, blade erosion phenomenon by water droplets is systematically studied. This manuscript discusses the results of a part of the work - effect of blade rotation speed on the blade erosion. The computational domain is modeled based on experiments being designed at our facility. The design consists of a rotating blade jig on which four blades are mounted. Rotary movement of the blades is incorporated in the numerical model by the use of sliding mesh method. A conical spray type water injection is used to model water injection from an impact-pin nozzle. Experimentally measured spray parameters like the flow rate, particle diameter, etc. are given as initial and boundary conditions in the simulations. The particles in the domain are tracked by Discrete Phase Model (DPM). Droplet parameters like average velocity, diameter and number of droplets hitting each cell on the blade surface are monitored and used to predict the erosion rate on the surface.