ISSN オンライン: 2688-7231
ISBN 印刷: 978-1-56700-497-7 (Flash Drive)
ISBN オンライン: 978-1-56700-496-0
Proceedings of the 25th National and 3rd International ISHMT-ASTFE Heat and Mass Transfer Conference (IHMTC-2019)
Measurement of the Extent of Cavitation using Vibration Monitoring in a Francis Turbine
A Francis turbine is generally intended to be operated at cavitation free conditions at the best design point. However, many times, it runs at off designed situations. Present work focuses on the occurrence and possible detection of cavitation phenomenon in a Francis turbine. A preliminary experimental work has been performed with a small scale Francis turbine model at different discharge, turbine speed and opening angle of guide vane to see the cavitation effect. The turbine was tested with a range of 200-395 l/min flow rate, 400-1600 rpm speed and 6-18° opening angle. This is done to understand and prepare the zone of operating parameters, where the extent of cavitation is significant. From this study it is understood that, cavitation is highly occurs at 400 and between 1200 to 1600 rpm. Moreover, at lower and higher blade settings the probability of the occurrence of cavitation is definite. Thereafter, a test block put over outlet of the runner to acquire the vibration signal, followed by Fast Fourier Transform (FFT) and it validated with visual observation data. It is observed that increase in cavitation level increases the amplitude of frequency peaks in 4-7 kHz range.