A Non-Dimensional Approach for Generalizing the Particle Impact Behavior of Gas Turbine Fouling

Abstract

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.

Environmental particle rebound/deposition modeling in engine hot sections

“…There are two major aspects to the damage caused by environmental particle ingestion in turbine engines (Suman et al, 2019). At low temperature, the particles are likely to bounce off the metal wall and cause damage by erosion, and at high temperature the particles become soft and can stick to an engine component wall.…”

“…2 State of the art in particle rebound/ deposition experiments and modeling Hamed et al (2006) comprehensively reviewed environmental particle erosion, rebound and deposition research in turbomachines from the late 1960's to the early 2000's. Suman et al (2019) systematically reviewed and analyzed more than seventy experimental datasets of coal particle, volcanic ash, and sand deposition relevant to engine hot sections from open literature, dating back 30 years. The current state of the art in testing and modeling of environmental particle ingestion into gas turbine engines was…”

“…As mentioned earlier, Suman et al (2019) comprehensively reviewed and analyzed over seventy experimental tests related to particle deposition in gas turbine hot sections, conducted over the last 30 years. The tests mainly involved five types of particles, coal, bituminous coal, lignite, volcanic ash, and sand.…”

“…Several empirical tests of spread factor quantifications for droplet impinging on solid surfaces were reported in the literature (Mao et al, 1997;Ukiwe and Kwok, 2005). A sensitivity analysis of ξ variation with the particle impact angle from 0 °to 90 °indicated that as the particle adhesion took place, ξ ≥ 0.4, and the value of 0.4 was suggested as the threshold value (Suman et al, 2019).…”

“…Suman et al (Suman et al, 2019) compared the energy-based sticking model with the critical viscosity model using all the deposition test data. They found that particle rebound and deposition regions differed between the two models, and mismatch between the actual experimental results and the model predictions were also observed.…”