Investigation of the Flow Characteristics for Cylinder-in-Ball Valve Due to a Change in the Opening Rate

Ball valves are widely used as flow control devices wherein a hollow, perforated ball pivots to control the liquid flowing through it. Due to a simple structure and only a quarter-turn of the stem required for either a fully open or fully closed state, ball valves are known for being durable with excellent shut-off properties, albeit without offering precise flow control. V-port ball valves are used as an alternative to allow for linear and even equal percentage flow characteristics, but a robust construction is required for higher velocity working fluids in the small end opening of the V-shape; otherwise, the valve could sustain damage. In the present study, a cylinder-in-ball valve is proposed through a structural conceptual design, wherein the opening begins at the center of the flow path. The flow characteristics and flow rates according to the opening rate were quantitatively evaluated via computational fluid dynamic analysis. The results showed that the flow coefficient, CV, with a range of 1.05~109.87, increased exponentially over the opening rates of 20~100%. A numerical analysis for the multi-phase flow was performed to calculate the vapor volume fraction to confirm the effects of cavitation. In addition, an experiment was conducted on the CV values to verify the validity of applying the proposed cylinder-in-ball valve as a flow control valve. Good agreement for the CV values was obtained between the experimental and numerical results.