Experimental study of liquefied gas dynamic leakage behavior from a pressurized vessel

Abstract

The accidental releases of pressurized liquefied gases from tanks involve violent phase transformation, which would generate two-phase releases and flashing jets. To investigate the evolution of leakage behaviors and make an analysis of near-field jet flow characteristics, a small-scale liquefied gas release experiment has been established. Leakage holes with different length-diameter ratio (LDR) have been used to analyze interactions between the leakage holes and release behaviors. Morphological characteristics of jet expansion angles have been obtained by high-speed camera, and jet velocities have been measured by particle image velocimetry (PIV). Meanwhile, the depressurization process, variation of temperature in the tank and mass outflow rates were obtained. Results show that, despite the LDR is varying, expansion angles and jet velocities behavior in the same tendency: decreases in the initial and maintains in a stable value for a period. The stable velocity status was worked by the balanced pressure drop. Thereafter, an empirical two-phase mass outflow rate model is developed based on the experimental data, which is related to the nozzle geometric parameter and upstream pressure, 90 % of the experimental data are within ±12 % of the prediction. Therefore, the empirical two-phase model can be supported in the mass flow rate evaluation, especially for the release cases that LDR are smaller than 5.00 but larger than 2.00. The experimental data is beneficial for providing further insight into the prediction of accidental release and risk assessment for the liquefied gas transportation and storage.