Experimental study on the flow characteristics during liquid nitrogen leakage

Abstract

ABSTRACT The accidental leakage from tanks and pipelines is one of the main risks in cryogenic superheated liquid storage and transportation. To investigate the effects of superheat degree and jet pressure on the leakage characteristics, the corresponding liquid nitrogen (LN2) leakage experiments were carried out under different conditions. In this study, a rectangular nozzle () was applied to imitate the crack in typical release scenarios. The dynamic evolution process of jet pattern was also investigated. Three jet patterns including the mechanical breakup jet, the partially flashing jet, and the fully flashing jet were identified in the stable stage. The results indicate that the jet angle rises with the increase of superheat degree. At high superheat degree, the jet pressure presents a more significant influence on the jet angle. While the superheat degree decreases, its influence on the jet angle reduces. The leakage mass flow rate declines with the increase of superheat degree and rises with the increase of jet pressure. Furthermore, a new discharge coefficient correlation suitable for superheated LN2 leakage is developed, and its prediction error is within±3.8%. The new correlation is a good tool to predict the mass flow rate during LN2 leakage process.