Evaluation and dynamic breakup of bubble size distribution of liquified natural gas release underwater

Abstract

With the demand for lower carbon emissions and the increasing use of clean energy instead of traditional fossil fuels, offshore production of liquefied natural gas (LNG) has become a major mode of energy transportation and storage. Due to its cryogenic characteristics, LNG produces special physical phenomena once it leaks from cargo ships or offshore pipelines. To investigate the mechanical behavior and thermal interaction between the jet-released LNG and surrounding ambient water, a set of laboratory experiments with various measurements was designed and developed to perform controllable cryogenic liquid horizontal release under water. The hydrodynamic phenomenon of flow behavior, effect of release dynamics, and instability mechanism of the breakup process caused by the formation of vapor bubbles were observed and quantified under different orifice sizes and release pressures. In addition, a four-stage physical model, established by Raj, that described the breakup dynamics transition from jet liquid to diffusion plume was validated and recorded using a visualized high-speed video camera. Two commonly used mathematical methods, the Rosin-Rammler distribution and lognormal distribution, were used to quantify and evaluate the average bubble sizes in 1.95 ± 0.06 mm, 2.18 ± 0.06 mm, and 2.2 ± 0.1 mm from 1, 3–5 mm, using image processing techniques. The bubble breakup mechanisms and empirical equations were developed and discussed with a complete set of literature data based on a non-dimensional analysis of various release conditions, which was validated with droplet size data obtained from laboratory studies in both gas and liquid co-flowing jets. The −0.38 power-law scaling relationship between the dimensionless length scale of d/lm and the mixture Weber number was established to predict the breakup of the vapor bubble size from subsea release fluids.