Effects of Compressibility on Flow Characteristics and Dynamics of Swing Check Valves—Part II

Abstract

Part II of this paper is concerned with two aspects of the dynamic behavior of swing-type check valves, namely, slamming of the disk and the maximum attainable reverse flow as the valve closes due to flow deceleration. Both aspects are well understood in incompressible flows, but not as well in applications involving fluids of relatively higher compressibility. A systematic approach in studying these phenomena in compressible flows is followed, and where possible, comparison with incompressible flow applications (e.g., water) is made. Both experimental and numerical investigations were carried out and results presented. Measurements were taken on an NPS 4 test rig in air and in water to provide fundamental comparisons of the two applications. The numerical investigation was based on the solution of the full equation of motion of the swing disk, including damping and counterbalance weights, and utilizing the valve opening-flow characteristics model developed in Part I in a quasi-steady manner. Transient flows in the connecting piping system upstream and downstream of the valve were analyzed based on the standard method of characteristics to solve the full one-dimensional conservation equations. Good agreement was obtained between numerical and experimental results which allowed further numerical investigations of the effects of various parameters in applications involving fluids of relatively higher compressibility.