Flame front propagation in combustion system with semi - open combustion chamber with different compression ratio

Researches of the combustion system with semi-open combustion chamber for spark ignition engines. This system was elaborated in Aircraft Engine Department of Heat Engineering Institute of Warsaw University of Technology. The researches concern the determination of influence CR on a flame front propagation into combustion chamber when CR and ignition advance are varied. The model combustion chamber make up with the constant volumes ratio of the prechamber volume to the prechamber plus main combustion chamber volumes, of 28%, but the CR were varied: 6:1, 8:1, 10:1 and 12:1, by changing of combustion chamber length. The researches were performed using rapid compression machine (RCM). The combustion sequences were recorded using high-speed digital camera with speed of 5000 frames per second. Simultaneously with combustion sequences recording, the high-speed pressure measurements were performed. The results of the visualization researches, with the pressure measurement results are presented in the paper. The research results show that the growth of compression ratio caused an improvement of combustion system performances; an increase of maximum cycle pressure and useful work field. The improvement of the performances is caused mainly by shortening of the combustion chamber length and approaching of supposed combustion course.