TURBULENT COMBUSTION OF A PROPANE-AIR MIXTURE

The paper models the combustion of a turbulent homogeneous mixture of propane and air within a duct having a stationary one-dimensional mean flow. The Bray-Moss model is applied to the closure of the chemical production terms, using a probability density function (pdf) of the temperature which is chosen as the characteristic variable. The chemical model of Edelman and Fortune for the combustion of hydrocarbons is used and simplifying assumptions are made which reduce the systems of unknowns to that of the temperature alone. This leads to the introduction of two chemical production terms which are defined respectively in a ″delay zone″ , where the heat release is modest, and a ″combustion zone″ . The required equations for the Favre-averaged temperature, turbulence kinetic energy, and the mean square fluctuation of the temperature are solved numerically. Good agreement is found in the case of relatively small turbulence intensity. Predictions are made of the profiles of mean temperature and mean square fluctuation under different initial turbulence levels.