On Vibrations of the Draft Tube of Water Turbines (1st Report)

Abstract

Although vibrations of the draft tube of water turbines have been frequently observed under part load operation, character and mechanism of the vibration are not known exactly. Some experiments on the vibration were carried out with a model of the draft tube of a water turbine, and the obtained results may be sumarized as follows : (1) The draft tube makes very complicated vibration with many frequencies. (2) There is one kind of dominant vibration, of which frequency varies as the rate of discharge, and its intensity becomes violent as the whirling angle of water increases. (3) Some kinds of longitudinal (axial) vibrations are likely to occur.