Hydraulic characteristics of orifice plate

Abstract

In some hydropower projects, the height of the dams exceed the level of 300 m. Orifice plate energy dissipater, as a kind of effective energy dissipater with characteristics of economic value, has been welcomed more and more by hydraulics researchers. The energy loss coefficient relating directly to the energy dissipation ratio is an important index for this energy dissipater design. In the present paper, this coefficient and relative parameters, such as contraction ratio of the orifice plate diameter and the flood discharge tunnel diameter, ratio of the orifice plate thickness to the tunnel diameter, and Reynolds number of the flow through orifice, were analyzed by theoretical considerations and their relationship expressions obtained by experiment. It could be concluded that the energy loss coefficient was mainly dominated by the contraction ratio of the orifice plate. The less the contraction ratio of the orifice plate is the larger is this coefficient. The research results demonstrate that the effects of Reynolds number could be neglected on this coefficient when Reynolds number is larger than 105 and that the orifice plate’s thickness has slight impact on the energy loss coefficient.