Computer and water-model simulation of flow through poppet valves

A computer code embodying a two equation turbulence model simulated two-dimensional steady flows through axisymmetric pipe expansions, with and without partial obstruction by a poppet valve. Steady and unsteady laminar flows through the valves were considered. The effect of valve geometry on the discharge coefficient was investigated. Satisfactory agreement is obtained between the predicted values of the discharge coefficient and experimental data. A water-model rig of a valve port and cylinder was used to visualize the flow pattern near the plane of enlargement. The computer simulation of such flows is validated by photographs of vortices. The experiments reveal that the mixing process in the circumferential direction, especially within the cores of toroidal vortices, takes place with unexpected rapidity. This diffusion cannot be reliably accounted for with the information available.