Estimation of the Particle Deposition on a Transonic Axial Compressor Blade

Abstract

Solid particle ingestion is one of the principal degradation mechanisms in the compressor section of heavy-duty gas turbines. Usually, foulants in the ppm range, not captured by the air filtration system, i.e., (0–2) μm cause deposits on blading and result in a severe performance drop of the compressor. It is of great interest to the industry to determine which areas of the compressor airfoils are interested by these contaminants as a function of the location of the power unit. The aim of this work is the estimation of the actual deposits on the blade surface in terms of location and quantity. The size of the particles, their concentrations, and the filtration efficiency are specified in order to perform a realistic quantitative analysis of the fouling phenomena in an axial compressor. This study combines, for the first time, the impact/adhesion characteristic of the particles obtained through a computational fluid dynamics (CFD) and the real size distribution of the contaminants in the air swallowed by the compressor. The blade zones affected by the deposits are clearly reported by using easy-to-use contaminant maps realized on the blade surface in terms of contaminant mass. The analysis showed that particular fluid-dynamic phenomena such as separation, shock waves, and tip leakage vortex strongly influence the pattern deposition. The combination of the smaller particles (0.15 μm) and the larger ones (1.50 μm) determines the highest amounts of deposits on the leading edge (LE) of the compressor airfoil. From these analyses, some guidelines for proper installation and management of the power plant (in terms of filtration systems and washing strategies) can be drawn.