This work presents the results of an investigation conducted to study the effect of coal ash particle size distribution on the particle dynamics, and the resulting blade erosion in axial flow gas turbines. The particle dynamics and their blade impacts are determined from a three-dimensional trajectory analysis within the turbine blade passages. The particle rebound conditions and the blade material erosion characteristics are simulated using empirical equations, derived from experimental measurements. For the typical ash particle size distribution considered in this investigation, the results demonstrate that the size distribution has a significant influence on the blade erosion intensity and pattern.

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In this work, a study has been conducted to predict blade erosion and surface deterioration of the free power turbine of an automotive gas turbine engine. The blade material erosion model is based on three-dimensional particle trajectory simulations in the three-dimensional turbine flow field. The particle rebound characteristics after surface impacts were determined from experimental measurements of restitution ratios for blade material samples in a particulate flow tunnel. The trajectories provide the spatial distribution of the particle impact parameters over the blade surfaces. A semi-empirical erosion model, derived from erosion tests of material samples at different particulate flow conditions, is used in the prediction of blade surface erosion based on the trajectory impact data. The results are presented for the three-dimensional particle trajectories through the turbine blade passages, the particle impact locations, blade surface erosion pattern, and the associated erosion parameters. These parameters include impact velocity, impact angle, and impact frequency. The data can be used for life prediction and performance deterioration of the automotive engine under investigation.

Gas turbine engines operating in dusty environments are exposed to erosion and performance deterioration. In order to improve the erosion resistance, nickel and cobalt superalloy blades and vanes are widely used in the hot section of gas turbines. Protective coatings have been used to enhance superalloy resistance to hot erosion. An investigation has been conducted to study coal ash particle dynamics and resulting blade erosion for both uncoated and coated blades of a two-stage axial flow gas turbine. A quasi-three-dimensional flow solution is obtained for each blade row for accurate computation of particle trajectories. The change in particle momentum due to collision with the turbine blades and casings is modeled using restitution parameters derived from three-component laser-Doppler velocimeter measurements. The erosion models for both blade superalloy and coatings are derived based on the erosion data obtained by testing the blade superalloy and coatings in a high-temperature erosion wind tunnel. The results show both the three-dimensional particle trajectories and the resulting blade impact locations for both uncoated and coated blade surfaces. In addition are shown the distribution of the erosion rate, impact frequency, impact velocity, and impact angle for the superalloy and the coating. The results indicate significant effects of the coating, especially on blade erosion and material deterioration.

Pulsating flow is as old as the human being. It appears in different forms from a compressible to incompressible, one phase, two or multi phase flows. Some forms of pulsating flow are favorable like that increase the combustion efficiency in combustors. Other forms of pulsating flow are harmful such as pulsation associated with compressor surge leading to increase of the noise level. Understanding the behavior of the pulsating flow in different forms, its effects on the flow system performance and on the gas turbine engine cooling system are reviewed. Reynolds number, velocity gradient, pressure gradient and frequency are the main parameters that affecting the pulsating flow behavior. The measurement of pulsating flow in its forms is one of the major tasks of the researchers. From the review it appears that number of researches tried to cover the whole sides of pulsating flow phenomena and the different ways to measure it. However, a lot of works is still needed to be understood thoroughly the effect of pulsating flow on the flow systems and how it could be used to developed the performance.