A combined experimental and numerical study of turbulent premixed flame propagation over multiple obstacles mounted in a semiconfined explosion combustion chamber is reported. The experimental method used a high-speed laser sheet flow visualization technique to record the progress of the flame front in a stoichiometric methane/air mixture. This allowed calculation of flame speed. Pressure was measured at two locations within the combustion chamber. For the simulations, transient Favre-averaged equations were solved using recent developments of a flamelet model. This model formulates the mean rate of reaction as a function of a transport equation for the flamelet surface density model. Both linear and nonlinear eddy viscosity turbulence models have been used and investigated for the closure of the Reynolds stresses.
Excellent agreement of flame structure and pressure impulse was obtained with the use of a nonlinear eddy viscosity turbulence model. It was also found that, irrespective of the eddy viscosity turbulence model, quantitative results of pressure and flame speed were found to be in good agreement with the experimental results. Regimes of combustion covered by the present study have been identified and found to reside in the wrinkled and corrugated (reaction sheets) flamelet regimes.