A non-dimensional approach for generalizing the particle impact behavior of gas turbine fouling

The consequences of particle deposition on gas turbine blade surface are studied since the first gas turbine application. The effects generated by particle adhesion range from performance deterioration to life reduction to complete loss of power. Even if, the effects generated by fouled blade surface are well known, the mechanisms responsible for the particle adhesion are still less clear. The variability related to the nature of materials, the impact conditions and the presence of promoting substances (such as water, oil, glue agents, etc.) imply several difficulties for comparing the results and for extracting general trends and rules useful for generating up-to-date predictive models. In the present work, an attempt to realize a general comparison among several different particle deposition tests is carried out. Starting from the previous review work, which has collected experimental tests carried out over thirty years, in the present study, an original elaboration data is proposed. Over seventy adhesion tests realized with particle composition, size, velocity, and temperature similar to those characterize gas turbine fouling are collected and post-processed. After a dimensional analysis, the data are then classified using non-dimensional groups such as Reynolds, Weber, and Ohnesorge numbers. In this way, general threshold values for the transitions between erosion, deposition, and splashing are identified according to the literature data. This general tool allows the a priori identification of the driving phenomena (such as inertia, viscous/capillary forces), based on the knowledge of basic inputs (such as impact and particle characteristics). The general approach adopted in this work gives the opportunity to increase the gas turbine fouling knowledge based on an interdisciplinary approach.