Abstract: The finite element method (FEM) and particle image velocimetry (PIV) technique are utilized to get the flow field along the inlet passage, the chamber, the metering port and the outlet passage of spool valve at three different valve openings. For FEM numerical simulation, the stream function y-vorticity w forms of continuity and Navier-Stokes equations are empl-oyed and finite element method is applied to discrete the equations. Homemade simulation codes are executed to compute the values of stream function and vorticity at each node in the flow domain, then according to the correlation between stream function and velocity components, the velocity vectors of the whole field are calculated. For particle image velocimetry experiment, pulse Nd: YAG laser is exploited to generate laser beam, cylindrical and spherical lenses are combined each other to produce 1.0 mm thickness laser sheet to illuminate the object plane, Polystyrene spherical particle with diameter of 30~50 mm is seeded in the fluid as a tracing particles, Kodak ES1.0 CCD camera is employed to capture the images of interested, the images are processed with FFT cross-correlation algorithm and the processing results is displayed by Tecplot. Both results of numerical simulation and PIV experimental show that there are three main areas in the spool valve where vortex is formed. Numerical results also indicate that the valve opening have some effects on the flow structure of the valve. The investigation is helpful for qualitatively analyzing the energy loss, noise generating, steady state flow forces and even designing the geometry structure and flow passage.

Key words: Finite element method (FEM), Flow field, Particle image velocimetry (PIV), Spool valve