DESIGN OF AN INNOVATIVE EXPERIMENTAL RIG FOR THE STUDY OF DEPOSITION PHENOMENA IN AXIAL COMPRESSORS

Compressor fouling is one of the main causes of gas turbine performance degradation. Fouling is promoted by micrometric particles of industrial pollutants in the air and unfavorable environmental conditions (fog, rain, humidity). Airborne particles ingested in heavy-duty gas turbines deposit on the compressor blades and sidewalls, increasing the surface roughness and changing the shape of the profile. This work aims to design a subsonic wind tunnel to study the gas turbine fouling phenomenon. Lump-parameter analysis and two- and three-dimensional fluid dynamics simulations support the design. Simulations were needed to optimize the blade cascade and identify particular fluid dynamic phenomena, such as separation, stagnation point, and vortex. In addition, great attention was devoted to the thermo-hygrometric conditions responsible for the capillarity forces. All these factors strongly influence the compressor cascade performance and the contamination rate. Particle concentration, number, and size are specified to perform a quantitative analysis of the particle impact on the blade surface and a qualitative analysis of the impact zones. As a result, realistic impact conditions of industrial relevance are reproduced in the wind tunnel in order to forecast the adhesion rate, the areas of the compressor airfoils impacted by particles, and thus the performance losses over the operation.