Dynamic simulation of swing check valve

摘要

The application of the CFD-simulation results to the simulation of a swing check valve in 1D flow simulation with finite difference methods is quite straight forward by solving the equation of movement Eq.(1). The transient fluid velocity at the entry to the valve follows from the fluid code. With the force factor F_f, Eq. (12) follows the effective force F_(eff) and further with Eq. (11) directly the hydraulic torque to the disk. The force factor F_f as well the loss factor K_(loc) are evaluated by this CFD simulation for steady flow and also for a transient flow with an gradient of 2.0 (m/s~2) of the inlet velocity. These results are transferable to other geometries as the parameters are non-dimensional. Conclusions can further been summarized into following: 1. The known effects of deviation and offset of the hydraulic forces acting onto the disc of a SCV valve are quantified for a static application. The modification of these effects in the dynamic case is demonstrated. 2. A non dimensional force factor applicable to the static one dimensional simulation of related SCV is quantified. On the bases of the force factor the critical velocity which is needed to fully open the SCV can be worked out reliably. 3. The static loss characteristic of a SCV can be evaluated by CFD in a reliable manner. The characteristic becomes modified in dynamic case. 4. The dynamic simulation of a SCV requires counting of the relative motions of the fluid and the disc. A simple model of the relative velocity is approved since longtime. In the very last closure phase of the disc the applied model seem to become inaccurate. 5. The acceleration of the angular velocity of the valve disc which counts for the added mass revealed as nonlinear function. It grows rapidly to the start of the valve movement and tends to damp out before the end of the closure.