Numerical Study on Extent of Hazardous Area for Sonic Jet Release Using Equivalent Leak Diameter

Abstract

In this study, three-dimensional K - E turbulence numerical simulations were conducted to analyze the extent of hazardous area for the sonic jet leakage of flammable gas. Incompressible fluid flows were simulated based on an inlet boundary condition estimated using the theory of “equivalent leak diameter” to prevent the direct simulation of sonic flows near the leakage hole. Numerical simulations of 20 methane leakage scenarios providing the lower explosive limit contour showed shapes of the hazardous area with a maximum height of approximately 12-14 times larger than the maximum width, owing to convection. The extents of hazardous area determined using computational fluid dynamics (CFD) were approximately 5%-10% lower than the results obtained with 1 m over based on IEC 60079-10-1. For scenarios in which quantitative data were not calculated using IEC 60079-10-1 due to low release rates, CFD provided quantitative data for the extent of hazardous area, showing nonlinear relationships with the pressure and diameter of leak holes.