Cubical Vessel

Laminar and Turbulent Burning Velocities of Premixed Hydrocarbon-air Flames in Closed Cubical Vessel

From the article:

Experimental measurements of laminar flame speed using spark-ignited explosions of methane-air mixtures in quiescent conditions in a cubic closed vessel are carried out. Experiments are conducted at initial pressure of 2 bar of stoichiometric methane-air mixture. Numerical simulations to determine the laminar burning velocity of stoichiometric methane-air, and turbulent burning velocity of propane-air mixture which include ignition and flame propagation is carried out using CFD software (CFX 5.7). The effect of pressure, stretch, flame thickness and confinement effects on the burning velocity is analysed. It has been found that when flame thickness in not negligible compared to the radius of curvature of flame and the vessel size, stretch, flame thickness and confinement effects are very important. Accordingly, these effects are taken into account to correct the values of laminar burning velocity obtained by pressure-time history assuming thin flame.

Simulation of turbulent combustion is performed using coherent flamelet model (CFM) [12] and the decay of turbulence during explosions and the effect of changes in pressure on both burning velocity and flow field are taken into account. A few experimental results of Checkel and Thomas [9] have been simulated and compared. The effect of initial values of rms turbulent velocity on turbulent burning velocity is analysed. Some of the deficiencies of the models have been brought out and attempts to improve these models are also reported.