CFD analysis of natural gas dispersion in engine room space based on multi-factor coupling

Gas supply systems typically located at the engine room space of LNG gas-fueled ships, present potential threats for fire and explosion due to gas leakage and dispersion. A validated Computational Fluid Dynamics (CFD) model is proposed for natural gas dispersion analysis in an engine room space under multi-factor coupling. Results demonstrate that gas dispersion depends on leakage rate, position and direction of release, temperature gradient, ventilation and the machinery equipment located in the engine room. Under the impact of air flow, temperature gradient and gas-buoyancy, natural gas tends to accumulate on the top of the engine room space, which can be pumped out through air-outlets. Natural gas is likely to concentrate at areas where vortex flows generate. Effective arrangement and locations of gas detectors are discussed considering the variation of gas concentration at several selected point within the engine room space. •Small leakage (0.0083kg/s) poses little threat to typical engine spaces.•Flammable gas (LEL≤υ/υ≤UEL) mainly situates in free jet flow area.•Flammable gas spreads around when jet flow is blocked.•Gas cloud concentrates near the celling and where vortex flows exist.•Detectors should be located near air-outlets, corners and under gas pipelines.