Relation of critical submergence depth with the axial velocity (Vz) in horizontal intake of power plants and its effect on the vortex strength

Hydroelectric plants are responsible the important role to generate electricity in a country and horizontal intakes is usually used to transfer water from the reservoir, In dehydration time of dams reservoirs, a phenomenon called vortex lead to reduces the efficiency of power plant and destroys the equipments of power plant .The water depth at the lower level that the strongest vortex is formed is known as the critical submergence depth and during operation of the dams should be not dehydrated at levels less than the this depth. So consider the most important factors on the critical submergence depth are very important. The axial velocity in this study as one of the most effective hydrodynamic parameters on the critical submergence depth and the vortex has been investigated with assisting of experimental model of Siahbishe dam (1/20 model) and numerical model of vertical two dimensional and with using of Fluent software