EXPERIMENTAL ANALYSIS OF THE MICRO-SIZED PARTICLE ADHESION IN A SUBSONIC STATIONARY CASCADE

The particle deposition phenomenon represents the critical factor for studying gas turbine fouling. Solid particle adhesion drives the contamination of the relevant surfaces of the power unit. Both compressor and turbine sides are affected by the performance degradation over time due to the contaminant adhesion. The performance losses are strongly related to the contaminants' characteristics and the gas turbine's operation. Solid contaminants like soil or soot coupled with environmental conditions such as temperature and humidity modify their stickiness, determining a difficult to predict effects on the gas turbine operation and reliability. According to the blade shape, surface characteristics, and flow field structures, particle impact determines the deposited layer growth process or the detachment/spallation of the previously deposited layer. This work analyzes the sticking and detachment processes generated by the interaction between solid substrate and micro-sized solid particles. The tests are carried out on a stationary linear subsonic cascade in which soil and soot particles are used to contaminate the flow field. A sensitivity analysis of the relative humidity values has shown how a slight increase in the relative humidity values determines the increment of the deposited contaminants by an order of magnitude. Blade regions and the overtime assessment of sticking and detachment processes are also assessed. Microsized contaminants interact with the blade surface, modifying the shape of the leading edge and the surface roughness, especially on the pressure side.