To realize a cooling of high efficiency of a rear wall and a burner portion by having a burner and a swirl device on the rear wall and forming a duct-like cooling air feeding device for compression fed for cooling which is connected to a flame tube in the burner at an exit side.

A plurality of burners 6 are mounted to a rear wall 5 of a flame tube 4 and swirl devices 10, 11 having ducts 12, 13 for feeding a combustion air coaxially disposed on a common center line A of the burner 6 and a combustion noise 9 to a primary zone P of a combustion chamber at each burner 6. An annular cooling air-feeding device 16 is formed between two wall portions T1, T2 on the rear wall 5. After the cooling air flows in an annular slot 16 and the annular cooling air-feeding device 16 and cools them, it is introduced to a burner outside annular space 19 communicated with all inlets of a duct 13 of the swirl device 11. A sleeve-like cover portion 20 and the annular space 19 axially extends to a further upstream side of the rear wall 5 are constituted so as to impart an energy to the swirl device 10 when a cooling air flowing out from the annular cooling air-feeding device 16 is utilized as a combustion air.