VERIFICATION OF INSTABILITY EFFECTS ON FLAME PROPAGATION IN CLOSED VESSEL BY CFD CODES

The aim of this work was to investigate the capability of commercially available CFD codes to simulate complex 3D-flame propagation which are encountered, for instance, in safety applications. Such codes claim to be able to well reproduce the turbulent flame propagation in complex real 3D configurations. However, the reliability of such simulations depends upon the capability of these codes to firstly represent the correct behaviour of simple and well-known configurations. It is not trivial what simple and well-known configurations are. Indeed, the numerical solution of the equations governing the development of a reacting flow-field is to be considered itself a not simple task. Moreover, the knowledge of fundamental properties of flame propagation is far from being fully understood. Therefore, it appears meaningful to perform a critical analysis of the results that can be obtained by commercial CFD codes applied to simple, lab-scale, configurations. Here, flame behaviour can become also very complex due to the appearance of effects induced by the strongly non-linear and unstable coupling between chemical phenomena and fluid dynamics. The propagation of a premixed flame in a closed vessel showing a characteristic instability (tulip flame behaviour, see f. i. Ellis, 1928) was chosen as simple test case. This kind of flame was successfully simulated by an academic code (Marra and Continillo, 1996).