Abstract
A simple non-return disc valve was tested in a pipe in which an unsteady flow was produced. The valve was tested with its disc fixed in position and was also tested with the disc controlled by a spring. Records were taken of the unsteady pressure diagrams at various points in the pipe and the disc displacement diagram.
To obtain the boundary conditions required for the unsteady flow calculation, it was first necessary to examine the flow in the valve under steady flow condition. The results of this investigation are briefly described.
It was found that the disc displacement diagram in unsteady flow can be calculated with reasonable accuracy from the pressure drop across the valve by integrating the equation of motion of the disc numerically. The equation of motion contains terms for the inertia of the disc, the spring force, and the gas force. Viscous friction damping forces were negligible for this valve.
Once the disc displacement is known, the pressure diagram can be calculated using the steady flow values for the pressure loss across the valve and the normal methods for one-dimensional unsteady flow calculations.
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