Experimental study and correlation analysis of breakup characteristics of liquid nitrogen jets

Abstract

Liquid nitrogen (LN₂) has garnered increasing attention due to its potential applications in various fields. When the LN₂ jet is accidentally released into an environment with a lower saturation pressure, it may lead to significant hazards due to the formation of a two-phase flow. In this study, a cryogenic experimental system with adjustable temperature and pressure was developed to investigate the two-phase flow behavior of LN₂ jets. The influencing factors affecting jet characteristics are quantified by Buckingham theorem. Through multiple regression analysis, the key feature parameters affecting the jet morphological transition are identified, and the transition criteria of different breakup regimes were developed. The results show that the transition criteria can accurately predict the morphological transitions from mechanical breakup to partially flashing and partially flashing to fully flashing, and the maximum error between the predicted results and the experimental data are within ±5 % and ±15 %, respectively. The key feature parameters affecting the discharge coefficient are identified by decision tree model, and the correlation of discharge coefficient in different breakup regimes is proposed by multivariate linear fitting method. The results show that discharge coefficient correlation has good predictive performance, and its maximum errors are within ±9.5 %, ± 5 % and ±15 %, respectively.