Hydraulic Losses of Flow Control Devices in Pipes

Concerning the vortex shedder used for the Karman vortex flowmeter, the flow resistances of cylindrical bodies of various cross-sections in a circular pipe are given by the general equation in the previous works of Igarashi et al. In the present paper, it is confirmed that the equation is applicable to the vortex shedder having a low opening ratio. Then, the same idea is applied to the hydraulic losses of flow control devices asymmetrical to the cross-section of the pipe, such as a sluice valve, a butterfly valve and a cock. Consequently, these hydraulic losses are expressed by the following general equation : ζ=C[(1-β)/β2]n, where β is the opening ratio.