Maxime Chiarelli’s PhD
With changes to the electricity mix and the growing need for flexibility in the energy system, Pelton turbines are subject to increasingly variable operating conditions, including, in particular, an increase in the number of starts, stops and speed changes. In addition to these stresses, hydro-abrasive erosion caused by sediment carried by the water is a further factor in Alpine hydropower schemes. These phenomena can gradually affect the integrity of the runners, making it particularly important to implement monitoring methods capable of tracking their condition during operation.
The doctoral thesis of Maxime Chiarelli has looked into the potential of methods based on vibration analysis to detect damage to Pelton turbines. The approach is based on the fact that the dynamic characteristics of a structure – and in particular its natural frequencies – change when its geometry or mechanical properties are altered. Monitoring these characteristics could therefore provide indicators for identifying changes in the condition of a wheel in a non-intrusive manner.
The work combined measurement campaigns on industrial Pelton turbines, experimental tests and numerical modelling in order to characterise the dynamic behaviour of the wheels under various conditions. Particular attention was paid to identifying their natural frequencies during operation, including during transient conditions, as well as to the influence of geometric parameters and hydro-abrasive erosion on their dynamic behaviour.
This research contributes to the development of new approaches to monitoring the condition of Pelton turbines and, in the longer term, predictive maintenance. They aim to better monitor changes in the condition of wheels during operation in order to assist operators in planning inspections and maintenance work.
Publications and related work
Doctoral thesis
Maxime Chiarelli, Damage Detection in Pelton Turbines Using Vibration-Based Methods, ETH Zurich, 2026.
View the thesis in the ETH Research Collection
Newspaper articles
Chiarelli, M., Decaix, J., Vetsch, D. F., Boes, R. M., & Münch-Alligné, C. (2026). Quantifying the Influence of Hydro-abrasive Erosion on the Dynamic Behaviour of Pelton Runners: An Experimental Study. Results in Engineering, 112074. https://doi.org/10.1016/j.rineng.2026.112074
M. Chiarelli, D. F. Vetsch, R. M. Boes, L. Andolfatto, and C. Münch-Alligné, ‘On the Influence of Geometrical Parameters and Erosive Wear on the Dynamic Behaviour of Pelton Turbine Runners’, 2025 Results in Engineering, https://doi.org/10.1016/j.rineng.2025.105638
Conference papers / proceedings
M. Boden, M. Chiarelli, V. Tsingos, N. Allaban, J. Decaix, S. Stojanovic-Roth, G. Blommaert, B. Valluy and C. Münch-Alligné, ‘Digital Twin for Vibration Monitoring of Pelton Units’, 2025, IOP Conf. Ser. Earth Environ. Sci. 1442 012008, doi:10.1088/1755-1315/1442/1/012008
M. Chiarelli, D. F. Vetsch, R. M. Boes, and C. Münch-Alligné, ‘Investigation of the natural modes of a Pelton runner prototype’, 2025, IOP Conf. Ser.: Earth Environ. Sci. 1483 012015, doi:10.1088/1755-1315/1483/1/012015
M. Chiarelli, R. M. Boes, D. F. Vetsch, G. Blommaert, M. Boden, and C. Münch-Alligné, ‘Identification of natural frequencies of Pelton runners during transient operating conditions’, Proceedings of the ISMA-2024 conference, Leuven, Belgium
M. Chiarelli, C. Münch-Alligné, D. F. Vetsch, and R. M. Boes, ‘Characterisation of dominant frequencies during transient operations of Pelton turbines at the FMHL PSP’, Proceedings of Hydro 2023, Edinburgh, Scotland
M. Chiarelli, V. C. Hasmatuchi, A. Amini, J. Decaix, D. F. Vetsch, R. M. Boes and C. Münch-Alligné, ‘On-site measurements of the dynamic behaviour of Pelton turbines in the context of predictive maintenance’, 2022, IOP Conf. Ser.: Earth Environ. Sci. 1079 012096, doi: 10.1088/1755-1315/1079/1/012096
Popular science article
M. Mettile, M. Chiarelli, J. Decaix, S. Rey-Mermet, and C. Münch-Alligné, ‘What challenges lie ahead for Pelton turbines?’, Electrosuisse Bulletin 1/2023
