The combustion system has a combustion chamber and a burner, with a feed channel (5) for supplying the combustion air and/or a fuel/air mixture leading to a mouth positioned at the burner. The feed channel has an adaption zone (8) in front of the mouth, for providing a fluid stream along the channel wall (7) formed by the combustion air, the fuel and the combustion gases. The channel wall of the adaption zone may be cooled.
