Abstract
Water Droplet Erosion (WDE) as a material degradation phenomenon has been a concern in power generation industries for decades. Steam turbine blades and the compressor blades of gas turbines that use water injection usually suffer from WDE. The present work focuses on studying erosion resistance of TiAl as a potential alloy for turbine blades compared to Ti6Al4V, a frequently used blade alloy. Their erosion behaviour is investigated at different droplet impact speeds to determine the relation between erosion performance and impact speed. It is found that the relationship is governed by a power law equation, ER ~ Vn, where the speed exponent is 7–9 for Ti6Al4V and 11–13 for TiAl. There is a contrast between the observed speed exponent in this work and the ones reported in the literature for Ti6Al4V. It is attributed to the different erosion setups and impingement conditions such as different droplet sizes. To verify this, the erosion experiments were performed at two different droplet sizes, 464 and 603 μm. TiAl showed superior erosion resistance in all erosion conditions; however, its erosion performance exhibits higher sensitivity to the impact speed compared to Ti6Al4V. It means that aggressive erosion conditions decrease the WDE resistance superiority of TiAl.
Highlights
800 μ m, water jet, rotating arm 45 to 130 μ m, water droplet, spraying water droplets on a stationary target
Experimental data were fitted to different functional forms in order to find the relationship between the erosion performance and the impact speed
The simple power relationship, equation (1), is the most used form to correlate erosion rate (ER) and V4,6,7. It implies that Water droplet erosion (WDE) takes place regardless how low the impact speed is
Summary
800 μ m, water jet, rotating arm 45 to 130 μ m, water droplet, spraying water droplets on a stationary target. Experimental data were fitted to different functional forms in order to find the relationship between the erosion performance (erosion rate) and the impact speed. The simple power relationship, equation (1), is the most used form to correlate ER and V4,6,7 It implies that WDE takes place regardless how low the impact speed is. An erosion-impact speed relationship based on this concern was developed, equation (2)[4], to fit the experimental data. It was not as accurately representing the experimental results as equation (1) in the usual range of impact speeds (1.5 < V/VC < 3 ). It is worth mentioning that the way of representing the ERmax is different in each case as explained in the table
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