The torque exerted by the flow around a swing check valve disk during transients strongly influences the dynamic valve-fluid interaction. This torque is difficult to quantify due to a lack of characterization data. Hydraulic torque can be separated into two components: the torque due to the flow around a stationary disk, and the torque due to the rotation of the disk. These components are expressed in terms of stationary and rotational torque coefficients. Laboratory tests on a 50 mm swing check valve show that the stationary coefficient is a function of the angular position of the valve disk only. The rotational coefficient is a function of disk angle, disk angular velocity, and the magnitude and direction of the through flow. Using these coefficients, numerical simulations of check valve slam transients can be made and the results compared with measured disk angle and pressure traces during such transients. The validity of the check valve characterization is demonstrated by the close agreement between the simulation results and the measurements.
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