Based on a real instance of liquefied natural gas (LNG) transportation engineering in a tunnel

a mathematical model of LNG leakage fire from pipeline was proposed with computational fluid dynamics (CFD) method.The LNG leakage fires under 3 different LNG leakage cases were simulated

and their changes in temperature distribution with time in the tunnel were calculated

through which the development of temperature distribution and fire risk were assessed.The simulation results showed that the rate in the tunnel temperature increase during fire is not high when the LNG leakage intensity is small

where the change in temperature is gentle and the fire risk is relatively low.The rate in tunnel temperature increase during fire is higher when the LNG leakage intensity is medium than the case of small intensity leakage

and the change in temperature is more severe

which makes the risk grow obviously.When the LNG leakage intensity is big

the fire temperature in the tunnel is highest among the three cases

the fire smoke will be seriously accumulated in the tunnel

which is very dangerous and should be avoided.