Numerical investigation of stretch effect for n-heptane/air mixture combustion process in constant volume chamber with the use of gradient method combustion model in LES

Paper presents the results of numerical simulations with combustion model for Large Eddy Simulation turbulence model. The numerical results are compared with experimental data. Combustion model is based on the gradient method which determines the flame propagation. Gradient is calculated from mass fraction of fuel or products. The laminar burning velocity is described by empirical correlation. In this work the influence of stretch factor on flame propagation is studied. From the results it is concluded that flame stretch factor is important for adequate representation of the combustion process in numerical simulation. With the adequate representation of the stretch factor and laminar burning velocity the results are in good agreement with experimental data. The gradient method combustion model for LES did not increase the time of calculation which makes it an attractive method in the simulations of full engine cycle.