To obtain a uniform fuel concentration and restrain the vibration of a fuel chamber by a method wherein a fuel nozzle, arranged on the axis of an eddy current generator or a burner, is surrounded by an outer coating while air, rubbing the surrounding of the fuel nozzle while passing through holes bored on the outer coating, is conducted to flow.

A fuel nozzle 103 is surrounded by a ring 190 with an interval. Holes 161, arranged in a circumferential direction, are provided on the ring 190. Air 160 flows into an annular chamber 180 through the holes 161 while rubbing the surrounding of a fuel nozzle. The holes 161 are directed obliquely toward the downstream direction of the flow of fuel whereby a predetermined axial component is generated in the axial line 60 of a burner. A fuel injector 170 is provided additionally under a condition that the same is connected to the holes 161 operationally. A predetermined amount of fuel is supplied by the fuel injector 170 into the air 160 whereby a fuel concentration 150, uniform across the sectional surface of the flow of fuel, is brought. According to this method, the uniform fuel concentration 150 stabilizes flame front at the outlet port of the burner whereby the pulsation of a fuel chamber can be avoided.