LES Simulation of a Turbulent Methane/Air Premixed bluff body flame with Non-Adiabatic Flamelet Progress Variable Approach

Abstract

A Large Eddy Simulation of a CH4/Air premixed bluff body flame is performed by means of a progress variable/flame surface density/probability density function approach. In particular, both mean and variance of the progress variable are transported. Its subgrid spatially filtered gradient contributes to model the flame surface density (that introduces the effect of the subgrid flame reaction zone) and to presume a probability density function (that introduces the effect of subgrid fluctuations on chemistry). Chemistry is tabulated in terms of laminar premixed flames and enthalpy is included as a new coordinate in their tabulation to take into account heat losses in the flowfield. The filtered mass, momentum, enthalpy and scalar equations mentioned above are integrated by means of an explicit scheme using finite differences, 2nd–order accurate in space and third order in time, over a cylindrical non-uniform grid using a staggered approach. The bluff-body geometry is modeled by using the Immersed Boundary Method. The predictions of velocity and temperature are compared with available experimental data.