Experimental Analysis of Combusting Flows Developing over a Plane-Symmetric Expansion

An experimental study of inert and combusting flows developing over a plane-symmetric expansion is presented. The flow under investigation consists :of two fully developed turbulent channel flows of air (inert flows) or air plus propane (combusting flows) that are emerging just ahead of the sudden expansion. Such a flow geometry has been chosen to test turbulent combustion models that are able to take into account either a variable-mixture composition or (and) the simultaneous presence of large-scale coherent structures and stochastic turbuience. The present study concerns cases for which both streams have the same mass flow rate and the same equivalence ratio. The results put into evidence the asymmetry of the inert mean velocity field. The most striking effect of the presence of combustion is the symmetry brought to the mean flowfield and the related statistics accompanied by a deterministic pulsation of the reacting zones whose amplitude is governed by the characteristics of the reactants streams. Such a dramatic change in the flow properties represents a great challenge as far as computations of these flows are concerned.