A Microscale-Based Methodology to Predict the Performance Degradation in Turbomachinery due to Particle Deposition

Solid particle ingestion is one of the main causes of gas turbine compressors degradation for both heavy-duty and aero-propulsion applications. Particles that enter the engine can stick to the internal surfaces and then form deposits. These, in turn, involve a change in the surface roughness and then performance deterioration. In the literature, several strategies have been proposed in order to account for the deposits effects on compressor numerical simulations. Among the others, the most used is the mesh-morphing strategy, which consists of the modification of the computational grid according to the particle deposition. Even though it is well suited for turbine fouling, the large computational costs and complexity of this strategy are not acceptable for compressor simulations. In this work, an innovative microscale-based approach has been proposed. An axial compressor deposition experiment from the literature has been considered as the reference case to test the reliability of the presented strategy. The main advantage of this approach consists of reducing both computational costs and numerical instability since it does not need the modification of the mesh. The deposition has been modelled by means of the OSU model and the roughness influence on the fluid flow has been accounted for by using the well-known sand-grain-roughness height (ks). Efforts have been made to find the ks correlation that best represents a fouled surface. The presented strategy enables the prediction of the fouling effects on axial flow compressors, and the prediction of the performance losses during the operation.