An investigation of compressible flow characteristics of butterfly valves.

Compressible flow characteristics including mass flowrate, onset of 'choked' flow, stagnation pressure loss, and static pressure recovery were investigated for butterfly valves. A simplified sudden enlargement in flow area theoretical model was used to characterize the essential features of the valve flow. A series of small scale compressible flow experiments was also conducted using sudden enlargement configurations with different nozzle geometries and using geometrically similar model valves. These experiments provided a database for augmenting the simplified theoretical model with needed empirical information and for assessing the range of applicability of the theoretical model. (from authors' abstract)