Abstract
Erosive wear of hydraulic machines is a common issue, which results in efficiency degradation, the enhancement of cavitation, and the need for expensive maintenance. Although numerical simulations of the erosion process could be very useful, both for understanding and predicting the process, its multiscale nature renders it very difficult to simulate. A previously validated multiscale model of erosion is presented. It consists of two coupled sub-models: On the microscale, the sediment impacts are simulated by means of comprehensive physical models; on the macroscale, the turbulent sediment transport and erosion accumulation are calculated. A multiscale simulation of the erosion of a prototype-scale Pelton bucket impacted by a sediment-laden water jet is presented. The simulation results, namely the erodent flux and the distributions of average impact angle and velocity on the bucket surface, bring insight into the erosion process. Furthermore, the results explain the obtained erosion distribution, which is in very good agreement with the experimental erosion measurements available in the literature for the same test case.
Highlights
Hydroabrasive erosion is the progressive removal of matter from a surface exposed to a fluid carrying sediments
It has become possible to quantitatively predict the erosion process of an industrial-scale hydraulic turbine. This achievement is possible thanks to the use of a multiscale model that bridges the scale separation between the sediment impact dynamics and the turbulent sediment transport hydrodynamics. This approach bypasses the need for uncertain erosion correlations by relying on accurate simulations of the sediment impacts, taking into consideration the sediment shape and elasticity and the high strain rate response of the base material, by means of comprehensive physical models
Does the model accurately predict the erosion distribution on the bucket surface; it brings information concerning the impact conditions and sediment flux against the wall, which allows for a better understanding of the erosion distribution results
Summary
Hydroabrasive erosion is the progressive removal of matter from a surface exposed to a fluid carrying sediments. The erosive wear of hydraulic turbomachines, notably Pelton runners and injectors, is a common issue resulting in efficiency degradation, the enhancement of cavitation, and outage for expensive maintenance [1,2]. Several erosion mitigation strategies can be used in the design and operation of Pelton turbines, for example: The use of hard coatings, the use of larger buckets, preventive shutdown whenever a critical sediment concentration threshold is reached, periodic maintenance by means of welding, and so on [3]. In order to find the best compromise among these mitigation strategies, Int. J.
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