Influence of sudden expansion geometries on cavitation behavior of control valves

Control valves, as the core components of flow control and pressure-regulating pipeline systems, critically influence operational safety and maintenance efficiency. Although cavitation induced by valve throttling is inherently challenging to eliminate, effective suppression strategies are essential to ensure valve reliability. Among these, post-valve pipeline expansion technology has emerged as a promising approach due to its structural simplicity and high efficiency. This study investigates the cavitation suppression mechanism of the sudden expansion body in two typical control valves (plunger valves and fixed cone valves) through integrated theoretical analysis, physical experiments, and numerical simulations. A quantitative correlation is established among the valve discharge coefficient, expansion ratio, and cavitation number. The results demonstrate that the sudden expansion body significantly enhances the valve's anti-cavitation performance, albeit with diminishing returns as the expansion ratio increases. Furthermore, based on hydraulic stability criteria and cost-benefit analysis, an optimal expansion ratio of 4.00 is proposed for single-valve circular expansion pipelines. This finding provides a practical trade-off between cavitation suppression efficacy and manufacturing costs, offering valuable insights for industrial applications.