Research on the combustion process of gasoline engine by high-speed schlieren method

Based on the principle of schlieren method and high-speed photography technology, a set of reflect-type schlieren system was built on one optical engine test bench. The diffusion process of blue flame at the initial stage of combustion could be recorded clearly by this system. Compared with the images taken by direct photography, the earlier generation of flame, the broader flame contour and the transformation of flame configuration could be observed from schlieren results. This system was then used to study the combustion process of gasoline engine. The effect of air/fuel ratio and load on the velocity of flame propagation and the flame configuration were analyzed. The results reveal that the addition of the mixture concentration near to stoichiometric ratio and the boost of the load makes the combustion more sufficient, the start of combustion earlier, the velocity of flame propagation faster and the wrinkle face of flame greater.