The role of orifice geometry in determining fibre production efficiency in pressurized gyration

• Geometric design optimization of the pressurized gyration vessel reveals a critical role in fibre morphology and production rate. • Quantitative comparisons show that increasing orifice number and lowering orifice height significantly enhance production efficiency. • Dual-level orifice configurations are introduced for the first time, offering a strategy to balance production output and fibre uniformity. • High-speed camera footage provides visual evidence linking fluid behaviour and fibre formation, supporting experiments findings. Pressurized gyration allows the scaled-up production of polymeric fibre under the simultaneous application of pressure and rotation. This study investigates the influence of orifice design on fibre formation and production rate in pressurized gyration, aiming to optimize the technique for industrial-scale applications. Transparent vessels with varying orifice heights (7.5 mm, 15 mm, and 22.5 mm), orifice numbers (24 and 48), and dual-level orifice distributions were fabricated and tested under pressures of 0.1, 0.2, and 0.3 MPa. Morphological analysis showed that fibre diameter decreased from 2.2 µm to 1.8 µm when pressure was raised from 0.1 to 0.3 MPa when increasing the number of orifices to 48. Two-level orifice designs yielded mixed diameter distributions, enabling tunable fibre architectures. High-speed imaging revealed that the 7.5 mm orifice height achieved fluid ejection 7.5 % faster than 22.5 mm at 0.1 MPa and increasing pressure from 0.1 to 0.2 MPa reduced ejection time by up to 33 %. Production rate increased with more orifices (48 compared to 24), by 9.8 % at 0.2 MPa, and declined at higher pressure for vessels with dual-level designs. Overall, the findings provide quantitative insights into how vessel geometry influences fibre morphology and throughput in pressurized gyration systems.