Simulation of flame acceleration and DDT in [formula omitted]-air mixture with a flux limiter centered method

Abstract

Flame acceleration and deflagration to detonation transition (DDT) is simulated with a numerical code based on a flux limiter centered method for hyperbolic differential equations. The energy source term is calculated by a Riemann solver for the inhomogeneous Euler equations for the turbulent combustion and a two-step reaction model for hydrogen–air. The transport equations are filtered for large eddy simulation (LES) and the sub-filter turbulence is modelled by a transport equation for the turbulent kinetic energy. The flame tracking is handled by the G -equation for turbulent flames. Numerical results are compared to pressure histories from physical experiments. These experiments are performed in a closed, circular, 4 m long tube with inner diameter of 0.107 m. The tube is filled with hydrogen–air mixture at 1 atm, which is at rest when ignited. The ignition is located at one end of the tube. The tube is fitted with an obstruction with circular opening 1 m down the tube from the ignition point. The obstruction has a blockage ratio of 0.92 and a thickness of 0.01 m. The obstruction creates high pressures in the ignition end of the tube and very high gas velocities in and behind the obstruction opening. The flame experiences a detonation to deflagration transition DDT in the supersonic jet created by the obstruction. Pressure build-up in the ignition end of the tube is simulated with some discrepancies. The DDT in the supersonic jet is simulated, but there is a discrepancy in the time of the simulated DDT.