Regulations require that industrial fans utilised in power generation, cement and steel applications must operate as part of a process that produces erosive particles. Over time these erosive particles erode centrifugal fan impeller blades, changing the blade profile and consequently, degrading fan performance. To replace the eroded impellers, operators must shut down the process. If one must replace an impeller between scheduled maintenance intervals, the associated costs with lost production become significant. Consequently, the industrial fan community is interested in predicting the erosion, and ultimately, a fan impeller’s in-service life when operating in an erosive environment. Industrial fan designers face challenges when attempting to predict impeller erosion. Industrial centrifugal fan impeller blades are routinely constructed from cambered plate, usually with backward or forward sweeping, with the inevitable consequence of separated flow regions. This separated flow is within a highly three dimensional flow-field making difficult an accurate prediction of the flow-field though an impeller with cambered plate blades. Assuming that one can accurately predict this three dimensional flow-field one must then go on to simulate the erosive particles’ trajectory.
This paper builds on the work of other scholars who have developed a computational approach that accurately predicts the flow-field though an impeller with cambered plate blades. The authors report an unsteady numerical analysis with the finite volume open-source code OpenFOAM. The analysis was undertaken using a moving mesh technique, based on Arbitrary Mesh Interface technology. Reynolds Averaged Navier-Stokes equations for incompressible flow were solved with a non-linear first order turbulence closure. They modelled particle transport and dispersion using a Lagrangian approach coupled with a Particle Cloud Tracking (PCT) model. Understanding the particle size effect facilitates identifying critical regions on the impeller blades most prone to erosion for each combination of particle sizes. Identifying the most critical regions thus provides a basis for modifying overall impeller and individual blade geometry in an effort to reduce susceptibility to erosion. This then increases in-service life, and consequently the time between maintenance intervals.