A review on erosion and erosion induced vibrations in Francis turbine

Abstract

Abstract Vibrations are one of the major issues observed during the operations of Francis turbine as they are frequently operated outside their optimal operating range, with rapid load changes. In hydropower plants, vibrations occur in various parts which can be classified as: hydraulic civil parts such as reservoir, intake, dam, tail race etc. mechanical parts such as penstock, turbine, draft tube and shaft, and electrical parts such as generator and transformer. However, due to the sediments and cavitation problems, the regions around rotating parts such as turbine experiences severe vibration. In the cases where the turbines need to be operated with high sediment load, the vibration problems could be further aggravated due to sediment carrying flow and declination of the surface morphology after erosion. This paper is based on a literature review to explore the characteristic effects of erosion and cavitation which could result in losses, vibrations, fatigues on the turbine materials and oblivious turbine failure. The study aims to correlate the erosion and cavitation due to abrasion with the pressure fluctuations resulting in vibrations.