Experimental study on hydrogen-blended natural gas explosion in utility tunnels: Explosion control and optimization strategy

At present, there are almost no explosion control measures and optimization strategies suitable for the gas compartment of utility tunnels. The optimized layout of gas explosion energy mitigation measures with efficient, economical and safe can prevent explosion accidents from destroying utility tunnels. The control efficiency of explosion severity of hydrogen-blended natural gas (HBNG) under combined explosion control measures was explored. The control measures (CM) include vent, spray, energy-absorbing materials, and cavity, and their control effects are compared. The results show that the control effect on explosive energy of CM is ranked as central vent > energy-absorbing materials > end vent > cavity. The spray is highly effective in extinguishing flames but has relatively poor suppression effect on overpressure. Under the combined action of reverse stretching at the central vent and the spray water curtain wall, a V-shaped flame is presented, indicating a slowing of flame speed. The combination of the central vent and the energy-absorbing material enhances the dissipation and transfer of the explosion energy, and cavity and central vent hinder the flame propagation under the action of the suction. Under the closed utility tunnel, the fire extinguishing effect of energy-absorbing material and spray is the best, and the effect of energy-absorbing material and cavity is the worst. The optimal strategy for controlling explosion propagation in the utility tunnel is the combination of vent, cavity and energy-absorbing material. This study provides theoretical support for ensuring energy supply security in urban utility tunnels.