Combustion process visualisation in rapid compression machine modelling combustion in spark ignition engines

Mixture preparation and combustion processes in internal combustion engines are very complex and very difficult to investigate. These processes run very quickly and their parameters are changed quickly and in wide ranges. Therefore, the interpretation of measurement results is very difficult and uncertain. The visualization methods applied in the combustion researches can help to interpret the results. For many years, the visualization methods have been developed at the Aircraft Engine Department of Heat Engineering Institute of Warsaw University of Technology, in the field of combustion in engines, detonation and gas dynamics research. In these researches, different method of registration of very fast changes of combustion were applied. The combustion experiments have been performed in constant volume bomb, rapid compression machines and experimental visualisation engines. In the last case, the electronic digital camera of Photram SA 1.3 has been used. This paper refers to the experiments, which were conducted using rapid compression machine. Their goal was explanation the combustion mechanism in combustion system with semi-open combustion chamber under different parameters of this system. The obtained results show a strong influence of combustion system parameters on combustion mechanism, especially on a compression ratio and ignition timing. The strong swirls were registered at all sharp edges on combustion chamber during compression stroke. These swirls had a strong influence on the combustion system operation.