HEAT FLUX TRANSFERRED BY A FLOW IN TURBULENT COMBUSTION
The prediction of heat fluxes through the walls of turbomachine combustors is an important practical problem. On a fundamental point of view, the problem arises of the influence of the turbulent combustion on the transfer processes within the flow.
An experimental mounting designed by ONERA allowed the measurement of the heat fluxes exchanged between a cold wall and a flame of premixed turbulent combustion. We brought to light a notable increase of the exchange coefficients in the reaction zone, these falling back to more classical levels when the combustion is finished.
In parallel, calculations have been performed, based on a model of turbulent combustion allowing a connexion between the mean reaction rate and the mean concentrations and temperature, as well as their fluctuations. The agreement between calculation and experiment is satisfactory. The theoretical analysis makes it possible to emphasize the influence of the wall on the reaction process itself. The resulting modification of the thermal field in the external zone of the boundary layer induces an increase of the exchanges between the wall and the flow.