DESIGN OF ENERGY DISSIPATION STRUCTURES OF IRRIGATION CHANNELS CONTROLLED BY HOWELL BUNGER VANES

Abstract: In Bahçelik Dam, water for irrigation and drinking water is discharged from the bottom outlet to main diversion channel when the reservoir water surface elevation is between1472 m-1500 m. During the operating stage, it is planned that the flow discharge will be controlled and released by the valves automatically depending on the water demand at the downstream of the main diversion channel. In this system; the valve type is characterized by opening, closing and regulating time of the valves for controlling system placed at the downstream of the main diversion channel and also compatibility of the valves with electronically steering working principals. Because of these objectives, Howell-Bunger valves which have not velocity limitation, are resisting to cavitation and water hammer, and can be manufactured in all diameters, and also are controlled by electronically are selected for water control system. In the experimental study, four Howell-Bunger valves each having D=1400 mm and maximum discharge capacities Q=8.5 m3/s were placed at the upstream part of the main diversion channel and they were tested in various valve openings to obtain optimum operating conditions of valves for all reservoir water levels during the operating of the dam in a 1/10 scaled model. In original project, flow measurements cannot be measured clearly as there is not uniform flow condition because of turbulence and flow jet flushing from the pumps. For this reason, there are some energy reducing structures have been added just upstream of the pumps. For this aim various shapes of energy dissipation structures at various distances from the pumps have been tested in order to find the one reduces the maximum energy. The final shape of the energy dissipater obtained by experimentally has supplied uniform flow conditions in the irrigation channel. In this study, the application of the energy dissipater structure was tested, and the results of the experimental studies are given.