Abstract: The effects of thermal load and the ratio(β)of centre and outring fuel flow on the length of flame and temperature field in a combustion chamber were studied by a numerical models of an adjustable length of flame gas burner on the platform of Fluent 63. The results indicated that changing the β of the burner can adjust the length of flame and the temperature field in the combustion chamber under a constant thermal load. The temperature field and the highest temperature in the combustion chamber under a constant thermal load change with the different β. The front high temperature zone gradually shrinks， while the back high temperature zone gradually expands and moves forward with the increasing of β. The length of flame changes short or long with the increasing of β when β<05 or β>05， respectively， and it is the shortest when the β is 05.

Key words: gas burner, combustion chamber, temperature distribution, length of flame, thermal load