Numerical study on flame acceleration and DDT in an inclined array of cylinders using an AMR technique

摘要

Flame acceleration and deflagration-to-detonation transition in an inclined array of cylinders embedded in a H_2-air gas are studied by solving the two-dimensional reactive Navier-Stokes equations with an AMR to resolve important events in the flow. The computations show three stages of flame acceleration and how they are affected by the inclination of the array. The initial stage is the flame acceleration due to the increase of the flame surface area by the flow around the cylinders. The entrainment of the flame in the wake of the cylinders contributes to the fastest flame acceleration for the inclination angle 0° at which the row of cylinders is parallel to the flame propagation. As the inclination angle varies, formation of funnels of unburned material in the wake becomes dominant, and the flame does not accelerate as quickly. In the second stage, shock-flame interactions are responsible for the flame acceleration. The high reaction rate in the shock-compressed material decreases the flame surface area, while sustaining the energy-release rate. The final stage is a quasi-steady state of supersonic propagation. Detonation ignited by a local explosion propagates as a quasi-detonation. For 0° inclination, the local explosion does not lead to detonation, and the flame propagates in the choking regime.