Author(s): S. Deniz; J. Speerli; T. Staubli
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Keywords: No Keywords
Abstract: Increasing the specific speed of hydraulic turbines causes an increase in kinetic energy of the water exiting the runner. This kinetic energy has to be recovered in the draft tubes. Losses of kinetic energy at the exit of the draft tube should be included in the process of optimizing the overall efficiency of a hydraulic system. Measurements were performed in order to quantify actual losses of kinetic energy for a typical low head turbine of high specific speed. The results of these measurements demonstrate high non-uniformities of velocity distributions. The type of velocity distribution depends largely on the point of operation. The non-uniformity of the velocity distribution leads to a considerable underestimation of the actual losses of kinetic energy related to the kinetic energy associated with the mean axial velocity.
Year: 1991