Effect of Congestion on Flow Field of Vented Natural Gas Explosion in a Kitchen

Abstract

The process of gas explosion venting in a typical Chinese civil kitchen was investigated using computational fluid dynamics technology, focusing on the impact of the scale and cross-sectional characteristics of congestion, such as common furniture and electrical appliances, on the explosion flow-field parameters. An asymmetrical distribution of congestion will cause the uneven combustion of explosion flames in the kitchen. The flame will initially spread on one side of the room and then accelerate toward the surrounding areas, thereby increasing the risk of indoor gas explosion. The typical indoor overpressure change process can be divided into five stages, among which Stage V is found to be related to pseudoclosed combustion. Large-scale congestion has an obstructive effect on the explosion flow field, but it changes under certain conditions, while small-scale congestion only acts as a promoter. The flat congestion cross section helps maintain the stability of the flame structure, whereas the continuous and abrupt change of the congestion cross section can induce strong turbulent combustion. The research results provide a theoretical basis for the prevention and control of natural gas explosion hazards in civil kitchens from the perspective of congestion scale and cross-sectional mutation.

Numerical Simulation of Interaction between Large‐Scale Congestion and Vent during the Natural Gas Explosion in a Kitchen

“…e physical model and the scenario simulated in this study is similar to that in [22]. To verify the correctness of the model, explosion overpressures calculated in [22] were compared with the experimental results of Bauwens et al [23]. e variation trend of the two was similar, which proved the applicability of the numerical method [24].…”

“…e numerical model uses an eightnode structural grid to discretize the space and subgrid technology to describe the effect of small-scale entities on the flow field [21]. e physical model and the scenario simulated in this study is similar to that in [22]. To verify the correctness of the model, explosion overpressures calculated in [22] were compared with the experimental results of Bauwens et al [23].…”

“…Meanwhile, the effect of the grid size has been verified also. e grid size (0.1 m × 0.1 m × 0.1 m) used in this study is same as those in [22].…”

“…e model kitchen size was set as 3.4 m (length) × 2.1 m (width) × 2.4 m (height). e layout of the objects in the room and the main simulation parameters are consistent with the description in [22], including the following: the window in Figure 1 was regarded as a square vent with dimensions of 0.8 m × 0.8 m; the lower edge was 1 m from the floor, and the opening pressure was 20 kPa. To accurately describe the impact of an external explosion on the indoor explosion flow field, the calculation domain was extended to five times the length of the room along the direction of the vent.…”

Numerical analysis of the explosion of gas tanks using computational fluid dynamics

“…Gas explosion overpressures in confined spaces were numerically simulated by Wang et al [15] and Li et al [16]. In addition to these studies, using computational fluid dynamics, Cen et al [17] and Pang et al [18] performed gas tank explosion simulations in an apartment and in a kitchen, respectively. Numerical research about explosion overpressures in urban and residential environments and the use of obstacles to mitigate shock wave effects was carried out by Costa and Doz [19] and Vyazmina et al [20].…”