Abstract
In designing spool valves which are widely used in hydraulic power applications, one of the most important problems is to estimate and reduce the axial force acting on the spool of the valve. This axial force can easily be estimated from momentum theory if the behavior of the jet issuing from the metering orifice of the spool valve is expected.
In the present paper, a three-dimensional model of the spool valve has been designed to observe the flow near the metering orifice. This model is made of transparent acrylic resins. The jet issuing from the metering orifice is visualized by a tuft method. The images of flow fields recorded by CCD camera are fed into a microcomputer and an digital image processing is employed to investigate the behavior of the jet.
