Author(s): Amir Khosrojerdi; Hadi Moradian
Linked Author(s):
Keywords: Bottom outlet gate slot; Cavitation; Vorticity; Turbulence flow
Abstract: One of the main parts used in hydraulic structures such as bottom outlet gate is a SLOT that by means of some parts known as abutment, move in a drawing way upward and downward in the slots. These slots play a particular role in conduit when they are in adjacency to fluid flow. In this research, the flow features in gate slot have been simulated with the use of a numerical modeling with Fluent software. On the basis of this simulation which has been done in a 2D condition, vortex flow pattern, Pressure and Velocity distribution in gate slot were considered. In order to evaluate the above simulated modeling, we took measures to compare computed data in the simulated model with measured data from hydraulic model in bottom outlet gate slot in Karun 4 dam. In spite of flow pass next to the slot, vortexes were produced, causes some damaging phenomenon like cavitation; such phenomena can be omitted or minimized with optimized design in the dimensions of slot. The mentioned model in three upstream pressure heads having 2, 3, and 4 meters of water has the discharge of 0. 21, 0. 261 and 0. 302 cubic meters per second respectively, and vorticity magnitude of 1500, 1870 and 2240 1/s in the slots were obtained. Another parameter studied in this research is pressure distribution in conduit and slot. The amount of average pressure in the slot with the increase of entrance head, increases as in the heads of 2, 3 and 4 meters the amount of average pressure in the gate slot are 9800, 14500 and 1700 Pascal respectively. Also change effect of ratio of depth to width (d/w) of slot is on vorticity, pressure and consequently cavitation is studied. Change in the ratio of depth to width causes alteration on average pressure and vorticity magnitude in slot. Based on the obtained results, the best ratio for d/w with respect to minimizing cavitation and vorticity magnitude is 0. 5; furthermore, in this ratio executive costs of project will reduce. In addition to the above mentioned analysis, the effect of change on flow pattern in the slot has been studied.
Year: 2013