Large eddy simulation of a propagating turbulent premixed flame

A large eddy simulation of a turbulent premixed flame propagating through a chamber containing a square obstruction is presented and discussed. The governing equations for compressible, reacting flows are Favre filtered and turbulence closure is achieved using the dynamic Smagorinsky subgrid model. A simple flame surface density model based on the flamelet concept is employed for the subgrid scale reaction rate. The simulation gives very good agreement with experimental results for the speed and the shape of the flame as it propagates through the chamber. The peak pressures, however, are underpredicted by 20-30%. Reasons for this are discussed and it is concluded that a more sophisticated combustion model is required for complex flows such as this one, if a more accurate prediction of the pressure is to be achieved.