The Impact Of The Model Constant A Of The Eddy Dissipation Model On Simulation

Due to the complexity of turbulent combustion, Many studies about turbulent combustion in various aspects has been done. Turbulent combustion model as a basic combustion simulation tool, from model building and to engineering application, has always received wide attention. The establishment of combustion model should consider many factors, such as the validity of the model, the feasibility of numerical simulation, the practicality of engineering application. Combustion model not only can improve the understanding of the mechanism of combustion, but also can stimulate new modeling ideas to optimize the combustion model. The Eddy Dissipation Model has been used extensively in turbulent combustion modeling because of its simplicity, good convergence, and reasonable accuracy. The reaction rate depends on the turbulent eddy decay rate ε/k, and can automatically select the component to control the reaction rate, that is why the model not only can be used in the Non-premixed flame, but also can be used in the premixed flame. There are two reaction constants in the EDM model:A and B. The constant B is designed for the simulation of premixed flames; only constant A is needed in the simulation of diffusion flames. The model constant A with the suggested value4has been used in numerous CFD applications without verification and validation.A systematic investigation of the model constant A has been carried out here. Nineteen turbulent diffusion flames including, turbulent non-premixed jet flames, turbulent non-premixed opposed flame, turbulent non-premixed bluffbody flames, turbulent non-premixed swrl flames are CFD simulated and the simulation results are compared with experimental data. It is revealed that the flame temperature predicted with A=4deviates from experimental data severely. An optimal A value can be found to match experimental data for each flame, this value depends on fuel, chemistry, and the turbulence intensity of combustion flow field. it varies between0.3and25for the19flames. A correlation of optimal A value with turbulent Reynolds number is presented; a modification to the original Eddy Dissipation Model is also presented and validated.