Abstract: The performance of a Stirling engine is closely related with the quality of combustion. Visual test bench is adopted, by using a highspeed camera to photograph combustion flame, the effect of gas ejector on the stability and the shape of ethanol flame was analyzed. According to the relationship between RGB and combustion mode in different ways, the change of combustion mode when ejected air is participating in combustion was studied. The results show that, with suitable amount of ejecting air, the stability of the flame is improved apparently, and the length of the flame is shortened, the fullness of the flame is increased significantly, and the mode of combustion becomes half premixed and halfdiffusion combustion.  

Key words: ethanol, substitute fuel, Stirling engine, gas ejector, flame characteristics