EFFECT OF GRAVITY ON THE PROPAGATION OF FLAMES IN TUBES

The influence of a gravity field upon flame propagation in a tube is studied. In the same manner as in the work of Zeldovich et al. left bracket 4 right bracket , the existence of a stagnation zone in the burnt gas enables one to calculate integral relations involving only the front shape and the upstream velocity field. These relations are used to estimate the curved shape of the front as well as its propagation velocity, as a function of the expansion ratio and the Froude number. This study neglects thermodiffusive effects which occur inside the flame thickness since the burning velocity is assumed to be constant. Finally, the validity of this approximation is discussed.