Numerical study on scaling effects and decoupled network-based simulation of gaseous explosion

This research seeks to improve the prediction efficiency of gaseous explosions realized by numerical simulations in a full-scale underground network using a decoupled method. To provide quick predictions of overpressure distribution of methane explosions in underground airway networks, a two-section theory is employed. The explosion space is divided into a driver section and a blast-wave section. Governing equations including conservation of mass, momentum, and energy, together with chemical reaction and turbulence models are solved for the driver and the blast-wave sections using computational fluid dynamics (CFD) solver ANSYS Fluent (3D-based) and Flowmaster (1D-based) respectively. The three dimensional (3D) and one dimensional (1D) numerical analyses are preceded separately (decoupled). In the driver section, the numerical calculation results with three variables (FLSF, HDSF, and concentration) considering the size of explosion space and methane concentration level for the driver section are stored in a database tool Microsoft SQL Server Express aims to generate a methane explosion source database. To validate the selected combustion and turbulent models, a series of lab-scale methane explosion experiments were conducted. In the blast-wave section, the influences of geometric changes are quantified by using 2D Euler equations, whereas the simulation results are used to adjust the 1D network-based modeling. The decoupled method is applied in two case studies and proved capable to predict the pressure distribution of methane explosions that occurs in a complex airway network. --Abstract, page iii