Characteristics of Pressure Surge Due to Whirling Water from Exit of Water Turbine Runner : 1st Report, Experimental Investigation of Similitude

Abstract

Concerning the model-prototype similitude of pressure surge due to rotating flow from exit of hydroulic-turbine runner, the experimental studies through model tests under various head conditions and based on a comparison of measured data of model and prototype under dynamically and geometrrically similar conditions were conducted with the following results. Frequency and amplitude of draft-tube suges were proportinal to the square root of head and direct proportional to head respectively, and also surge frequency was inversely proportional to the dimension. From these relations, similitudes of frequency and amplitude were elucidated with dimensionless parameters. These parameters between the model and the prototype coincide very well at definite values of gate opening, revolving speed per unit head and unit dimension, and cavitation coefficient, moreover at corresponding positions for amplitude. Using these parameters, the procedure to predict draft-tube surge characteristics of the prototype from the model test results has been established.