Hydraulics and Fluid Mechanics

Abstract

In order to extend the prediction of butterfly valve characteristics to compressible flows and unusual geometries capable of giving a low self-closing torque, a simplified analysis of butterfly valve behaviour is necessary. In the paper an analysis based upon regarding the butterfly valve as two non-interacting jets is presented and compared with an orthodox “exact” solution for a plane butterfly in a parallel channel. It appears that the jet-flow analysis gives results closer to available experimental values, at least when the valve approaches closure, than does the “exact” analysis. It is concluded that the jet-flow analysis will be useful for designing unusual butterflies. However, more careful experiments are needed, both with plane channels and pipes to give reliable data for comparison with theory.