Numerical Study of Fillet Effects on Cavitation Development in Double Contraction Pipes

Abstract

This study investigates the effects of fillet geometry on cavitation development in series pipe systems with double sudden contraction using numerical simulations. The research evaluates how variations in fillet radius at contraction joints and inlet flow rate affect pressure distribution and cavitation characteristics. Three pipes with diameters of D, 0.6D, and 0.4D were arranged in series, with flow rates ranging from 500 to 3000 l/min. Simulations were conducted using ANSYS Fluent with the k-E turbulence model and Zwart-Gerber-Belamri cavitation model to predict vapor volume fraction and cavitation potential. Mesh independence verification ensured simulation accuracy. Results showed that the first contraction presented minimal cavitation risk, with cavitation number values above 0.5 across all conditions, while the second contraction showed significant cavitation, especially at higher flow rates. Increasing the fillet radius elevated local minimum pressure, reduced peak vapor fraction, and shortened the cavitation zone. Fillets helped smooth velocity gradients and reduce flow separation, lowering cavitation likelihood. These findings highlight the importance of geometric modification in minimizing cavitation and improving system durability. The study provides useful insights for designing more resilient industrial piping systems under high-flow conditions by combining flow control strategies and joint geometry optimization.