Computational Fluid Dynamics Simulation of Pneumatic Conveying of Radioactive Liquid Sampling Vials

To determine the motion characteristics of radioactive liquid sampling vials in pneumatic conveying systems in the nuclear industry, computational fluid dynamics (CFD) was employed to perform fluid–structure interaction (FSI) numerical simulations of the startup process of sampling vials under two—horizontal and vertical (upward)—conveying conditions. The motion of the sampling vial under various combinations of vacuum levels (−3 to −20 kPa) and gas volumetric flow rates (0.001 to 0.01 m3/s) was simulated to determine the transient velocity and pressure fields. The airflow velocity is lowest and the pressure is highest at the tail end of the sampling vial. For horizontal conveying, when the gas volumetric flow rate is insufficient, the vial tilts and becomes unstable due to gravity, preventing normal conveying; for vertical conveying, under high vacuum but low flow rates, the thrust pressure at the bottom of the vial is insufficient to overcome gravity, also resulting in conveying failure. Therefore, the gas volumetric flow rate has a greater impact on the conveying performance than the vacuum level. Under −5 kPa and 0.01 m3/s, the maximum velocity of the vial reached 20.39 m/s and 16.5 m/s, respectively, for horizontal and vertical conveying. These research findings can serve as a reference for optimizing the operating parameters and engineering design of the pneumatic conveying system for radioactive liquid sampling vials for the nuclear industry.