Author(s): P. P. Jonsson; M. J. Cervantes
Linked Author(s):
Keywords: No Keywords
Abstract: The scope of this paper is time resolved pressure measurements on a model turbine for validation of numerical simulations and a survey of scale-up formulas since the corresponding prototype is available for similar measurements. The measurements were performed on a 1:3. 1 scale Kaplan model turbine with a rotational speed of696.3 rpm. The pressure sensors were flush mounted at 20 positions around the draft tube cone and 13 positions in the elbow. A reference pressure in the draft tube outlet was measured simultaneously during all measurements. An encoder was used to resolve the angular position of the runner to the sensors. Three different loads were investigated with a constant blade angle: at peak efficiency, part load and near the full capacity. Vortex breakdown was present at off-design in both cases. At the peak efficiency point the main frequency is the runner rotational frequency. The blade passage frequency is also present in the upper part of the cone. High pressure peaks are present in the draft tube at part load due to the vortex rope existence at this regime. The vortex rope has a frequency of about 0.175·fn.
Year: 2009