A risk-based optimal pressure relief opening design for gas explosions in underground utility tunnels

Numerical investigation of the in situ gas explosion fracturing and the enhancement of the penetration in coal seam boreholes

“…The initial conditions for the control simulation were set to follow the standard composition of “normal” air, as defined in the scenario menu, comprising 20.95% oxygen and 71.05% nitrogen by volume. The gravitational constant was set to 9.8 m/s 2 , the temperature to 297 K, and the initial pressure to 101325 Pa. FLACS standard Reynolds‐averaged Navier–Stokes equations for turbulence models 29,30 …”

“…However, these pressures are on average 5% lower than those observed under conditions with diameters of 0.6, 0.8, and 1 m. The maximum pressure increase rate parameters are similar for L/ Φ > 5. Studies 30 have also shown that the larger the space, the higher the gas explosion pressure, but this is limited by the peak gas explosion pressure. The maximum explosion pressure does not increase significantly and the peak pressure stabilizes at 0.783 MPa when the reaming diameter reaches 0.6 m. As shown in the figure, the time to peak pressure for the gas explosion tends to decrease and then increase as the diameter of the gas chamber increases for different experimental conditions.…”

“…constant was set to 9.8 m/s 2 , the temperature to 297 K, and the initial pressure to 101325 Pa. FLACS standard Reynolds-averaged Navier-Stokes equations for turbulence models. 29,30 Gas and air premixes are assigned values according to the equivalence ratio. 23 They obey Equation (1):…”

Dynamic resilience assessment and emergency strategy optimization of natural gas compartments in utility tunnels

“…Also, for a utility tunnel, a large-scale infrastructure, it is not possible to experiment on a real scale, and the results of small-scale tests cannot be directly applied in practice (Zhao et al, 2022). Although some numerical simulation research was conducted to analyse natural gas leakage, diffusion, and explosion inside utility tunnels to optimize pipeline allocation, fire zone, or safety barriers (Baalisampang et al, 2019;Bu et al, 2021;Xu et al, 2021). But these studies focus more on the gas dispersion behavior, gas concentration field, explosion overpressure, and corresponding physical mechanism instead of comprehensive system performance.…”