Iranian Journal of Chemical Engineering (IJChE)

Abstract Liquid Composite Molding (LCM), particularly the Resin Infusion (RI) process, has become an attractive manufacturing technique for producing lightweight composite vessel hulls with improved structural performance and reduced production costs. Nevertheless, achieving rapid and uniform resin impregnation while preventing dry spots and premature gelation remains a major challenge. This study presents a numerical investigation of the resin flow behavior in the manufacturing of small composite vessel hulls using a two-phase computational fluid dynamics model based on the Level-Set Method. Five resin injection configurations, including cylindrical, fishbone, radial, parallel, and alternating arrangements, were systematically evaluated in terms of the resin flow pattern, filling time, pressure distribution, and gelation behavior. The numerical model was validated against an analytical gelation-time correlation, resulting in the prediction errors of only 2.60% for the cylindrical configuration and 1.35% for the fishbone configuration. Compared with the conventional cylindrical arrangement, the fishbone configuration reduced the gelation time from 127 min to 96 min, corresponding to an improvement of approximately 24%, while achieving complete mold filling before gelation. Among all investigated strategies, the alternating and radial configurations exhibited the shortest filling times of approximately 30 min and 35 min respectively, whereas the parallel configuration required nearly 120 min. Furthermore, the cylindrical configuration filled only about 90% of the mold before gelation. The results demonstrate that optimized inlet configurations significantly improve the resin distribution uniformity, reduce filling time, and enhance manufacturing efficiency, providing practical guidelines for the design and optimization of resin infusion processes for composite marine structures.