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INVESTIGATIONS OF POLLUTANT PREDICTIONS WITH LES-CMC MODELLING IN A BLUFF-BODY STABILIZED NON-PREMIXED FLAME

Salvador Navarro-Martinez
Department of Mechanical Engineering, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, UK

A. Kronenburg
Department of Mechanical Engineering Imperial College London London SW7 2AZ, UK

W. P. Jones
Mechanical Engineering Department, Imperial College London London, SW7 2AZ, UK

Abstract

The Large Eddy Simulations (LES)-Conditional Moment Closure (CMC) method is applied to a bluff body stabilized flame. First, computations of the velocity field and mixture fraction are compared with experimental data and the influence of grid size and inflow boundary conditions is analysed. Then, predicted reactive species mass fractions are compared with measurements in conditional and in real space. It can be shown that conventional steady flamelet methods cannot predict accurately intermediate species such as CO and criteria pollutants such as NO and the solution of the unsteady CMC equations is required to predict NO and CO satisfactorily since species mass fraction vary with downstream distance. The quality of NO and CO predictions is comparable to the best existing species predictions of the Sydney bluff-body burner, but temperature is markedly overpredicted close to the nozzle and predicted CO and NO mass fraction are generally somewhat above measurements.