Effects of control devices on flows in ball valve

Two different control devices utilized to linearly control the volumetric flow rate in a full-port 1/4 turn ball valve were studied. These control devices were called V-ports and R-ports. Effects caused by these control devices on fluid flows and flow performance coefficients in the ball valve were investigated. Computational techniques and experiments were employed. Flow patterns were given using the particle tracking flow visualization (PTFV) technique and numerical models. Vortical structures were observed in the flow field. Three performance coefficients, including the loss coefficient, the flow coefficient and the cavitation index, were estimated using the measured pressure drop and volumetric flow rate. In terms of flow coefficients, it turned out that these control devices were able to linearly control the volumetric flow rate through a ball valve, but they also caused several disadvantages. They increased the pressure drop between the inlet and outlet of a ball valve, so the resultant loss coefficients increased. Besides, the flow coefficients decreased. Meanwhile, cavitation phenomena were observed in flow fields when these control devices were used in the piping system. The cavitation index increased, showing that the possibility of cavitation was raised when these control devices were employed.