Non-Return Valve

Description

This project simulates a non-return (check) valve, a device that allows flow in one direction while blocking reverse flow, using ANSYS Fluent. Such valves are needed wherever downstream pressure can rise above inlet pressure, since without them the flow would push backward through the system and potentially damage it. The valve motion is captured through dynamic mesh with one-degree-of-freedom rotation, letting the valve flap swing open and closed in response to the flow rather than following a prescribed motion. The inlet velocity is driven by a UDF that ramps up to 1 m/s over the first 0.4 seconds, then drops to a near-zero value of 0.000001 m/s afterward, simulating an abrupt loss of driving flow. The geometry is a 26 cm × 5 cm two-dimensional domain built in SpaceClaim and meshed in ANSYS Meshing with an unstructured grid of 61,580 elements.

Methodology

The valve dynamics are handled through the Six DOF solver with only one rotational degree of freedom enabled, and a spring stiffness of 1 N·m/rad is added to help drive the valve closed once the flow subsides. Turbulence is modeled with SST k-omega, and the solution uses a transient, pressure-based solver with gravity neglected. The inlet is a velocity-inlet driven by the UDF profile, the outlet is a pressure-outlet at 0 Pa gauge, and all other walls are stationary. Pressure-velocity coupling uses SIMPLE, with second-order discretization for pressure and momentum, and first-order upwind for turbulent kinetic energy and dissipation rate; initialization is standard.

Analysis

The results show the valve opening for the first 0.4 seconds while the high-velocity, high-kinetic-energy inflow pushes it open, then beginning to close as soon as the flow velocity drops toward zero. The spring force reinforces this closing motion, accelerating valve closure and ensuring the flow cannot slip back through the inlet once the driving pressure is gone. The reported UDF velocity-versus-time profile and the force-on-valve-versus-time plot together show this open/close cycle directly, tying the valve's mechanical response to the imposed flow transient.