Objectives  The electric propulsion dual-fuel engine is becoming dominant in newly built Liquefied Natural Gas(LNG)carriers. To avoid the potential risks that accompany the use of flammable and explosive boil-off gas, the performance of precise safety and reliability assessments is indispensable.

  Methods  This research concerns the engine rooms of large LNG carriers which are propelled electrically by a dual-fuel engine. Possible fuel gas(natural gas)leak cases in different areas of the engine room are simulated and analyzed. Five representative leak cases defined by leak form, leak location and leak rate are entered into a Computational Fluid Dynamics(CFD)simulation, in which the Reynolds stress model of Fluent software is adopted as the turbulence model. The results of the leaked gas distribution and ventilation velocity field are analyzed in combination to obtain the diffusion tendency and concentration distribution of leaked gas in different areas.

  Results  Based on an analysis of the results, an optimized arrangement of flammable gas detectors is provided for the engine room, and the adoption of an explosion-proof exhaust fan is proven to be unnecessary.

  Conclusions  These analysis methods can provide a reference for similar gas leakage scenarios occurring in confined ventilated spaces. In addition, the simulation results can be used to quantitatively assess potential fire or explosion damage in order to guide the design of structural reinforcements.