PIV experiments on a valve for the handling of liquids

Particle Image Velocimetry (PIV) is employed to investigate the flow field inside the dummy of a prototype valve to be used for the industrial dosage of liquids. Velocity fields are reconstructed in three regions of the valve passages and for two values of the flow rate. Distilled water is used as the working fluid. Optical limitations were faced during the setup of the apparatus and a description of the expedients adopted is reported. Time-averaged velocity fields reveal the presence of critical fluid behaviours such as throttling, asymmetric flows and vortex generation. Those effects strongly affect the valve performance. The quality of PIV measurements is verified by comparing the experimental data with the results of RANS-based numerical simulations. Contour maps and velocity profiles obtained with the two methods show a very good agreement, thus demonstrating the reliability of PIV in this specific context. A first attempt was also made to characterize the jet flow at the valve outlet using PIV. It is found that in this case the accuracy of the measurements deteriorates, due to the presence of fluid-dynamic instabilities at the jet surface.