Pressure pulsations and stress in a high head turbine ? comparison between model and geometrically similar prototype.

Abstract

AbstractThe aim if this Master?s thesis was to establish relation between pressure pulsation amplitude in a model and a geometrical similar prototype. Model test has been conducted in the Water Power Laboratory at Norwegian University of Science and Technology (NTNU). The data collected from the model test has been compared with corresponding data from field measurements at the geometrical similar prototype. Three operation points have been compared; these were 42 %, 50 % and 75 % load. The comparisons were made from three different locations; draft tube cone, runner blade and vaneless space. As a scale-up relation the A/H fraction has been tested, but none of the pressure transducer showed a tendency to follow this relation. Moreover it have been conducted pressure pulsation measurements on the model turbine for different sigma levels. These measurements were conducted at 50 % load with four different sigma levels with the range of 0.026 to 0.050. The sigma variation influence proved to be significant in the draft tube, and marginal in the runner. For the vaneless space the influence could be neglected. However the results from all the transducers showed a tendency of an increase in pressure pulsation amplitude with decrease in sigma level.