Experimental and numerical study on flashing jet characteristics in the leakage process of hazardous liquefied gas

The flashing jet process in the vicinity of leak is vital to determine safe distance for risk assessment and safe protection. This paper investigates the flashing jet characteristics during R134a release with different leakage nozzle diameter by small-scale experiment and computational fluid dynamics (CFD) simulation. Pressure and temperature variations inside the tank in the leakage process are calculated through thermodynamic method and used to determine leakage parameters, which are integrated into the simulation by User-Defined Function (UDF). Simulated results are in good agreement with experimental data. The pressure inside the tank decreases, leading to significant decreases in both the velocity and velocity peak area, with the maximum decrease of 30 % and 80 %, respectively. Additionally, jet velocity increases along the core axis, displaying a discontinuous velocity distribution. As the leakage nozzle diameter increases, both the core and transition regions expand, and a dense two-phase region forms at the rear of the flashing jet. Due to the phase transition, the jet temperature decreases sharply by 77 K in the initial stage, then stabilizes over time. A region of low temperature and droplets overlaps within 0.4 m from the leak. The initial diameter of the droplets increases from 0.033 mm to 0.036 mm as the internal pressure decreases. As leakage continues, droplet velocity decreases, and the dispersion distance of the cloud fluctuates based on the parameters of the leakage source.