{"title":"On gravity-driven liquid nitrogen jets reach and horizontal spread for extinction of ground fires by aerial means","authors":"","doi":"10.1016/j.firesaf.2024.104278","DOIUrl":null,"url":null,"abstract":"<div><div>This paper describes experimental and numerical results on the reach and the spread of gravity-driven jets of liquid nitrogen (LN<sub>2</sub>) on the ground for applications to fire extinction by aerial means. A series of experiments released LN<sub>2</sub> jets from different elevations in ambient air to measure their reach and spread distances upon the impingement. A numerical model was developed to simulate the behavior of such jets. Upon validation, the numerical model was used to further predict the LN<sub>2</sub> pool mass and spreading distances under various release configurations. Results showed that the LN<sub>2</sub> survivability is greatly affected by the release height of the cryogen, since the LN<sub>2</sub> quantity reaching the ground decreases as the release height increases. Moreover, releasing larger initial LN<sub>2</sub> quantities and, most importantly using larger nozzle diameters, both the LN<sub>2</sub> pool mass and spreading diameter can be extended. Additional experiments were conducted where cryogen jets were released onto small (∼300 cm<sup>2</sup>) alcohol pool fires; results showed that only limited quantities of the LN<sub>2</sub> evaporated in transit to the fire, and small amounts of the cryogen expediently snuffed the fires. A simplified model also suggested that in fire supression/extinction by LN<sub>2</sub> the fuel cooling mechanism is of secondary importance compared to the mechanism of separating the fuel from oxygen.</div></div>","PeriodicalId":50445,"journal":{"name":"Fire Safety Journal","volume":null,"pages":null},"PeriodicalIF":3.4000,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Fire Safety Journal","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0379711224001917","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, CIVIL","Score":null,"Total":0}
引用次数: 0
Abstract
This paper describes experimental and numerical results on the reach and the spread of gravity-driven jets of liquid nitrogen (LN2) on the ground for applications to fire extinction by aerial means. A series of experiments released LN2 jets from different elevations in ambient air to measure their reach and spread distances upon the impingement. A numerical model was developed to simulate the behavior of such jets. Upon validation, the numerical model was used to further predict the LN2 pool mass and spreading distances under various release configurations. Results showed that the LN2 survivability is greatly affected by the release height of the cryogen, since the LN2 quantity reaching the ground decreases as the release height increases. Moreover, releasing larger initial LN2 quantities and, most importantly using larger nozzle diameters, both the LN2 pool mass and spreading diameter can be extended. Additional experiments were conducted where cryogen jets were released onto small (∼300 cm2) alcohol pool fires; results showed that only limited quantities of the LN2 evaporated in transit to the fire, and small amounts of the cryogen expediently snuffed the fires. A simplified model also suggested that in fire supression/extinction by LN2 the fuel cooling mechanism is of secondary importance compared to the mechanism of separating the fuel from oxygen.
期刊介绍:
Fire Safety Journal is the leading publication dealing with all aspects of fire safety engineering. Its scope is purposefully wide, as it is deemed important to encourage papers from all sources within this multidisciplinary subject, thus providing a forum for its further development as a distinct engineering discipline. This is an essential step towards gaining a status equal to that enjoyed by the other engineering disciplines.