Independent component analysis applied to combustion images in transparent engines

High speed and high resolution im¬aging devices coupled with optically accessible engines constitute a very powerful investigation tool, permit¬ting for detailed investigation of the transient phenomena taking place in the chamber of internal combus¬tion engine. Impressive amount of data that can be collected during experiments and complexity of the phenomena involved requires implementation of the sophisticated mathematical tools. In this work, a method of Independent Compo¬nent Analysis (ICA) was used to separate spatial structures related to different combustion events. In particular, the paper reports on the analysis of the combustion dynam¬ics by means of ICA technique ap¬plied to 2D line-of-sight images of combustion-related luminosity, col¬lected from two different optically accessible engines: Diesel and port fuel injection spark ignition (PFI SI). The method is used here for the extraction of the independent com¬ponents, which are expected to de¬scribe the underlying patterns of the combustion process. The determined components and their coefficients are then used to analyze the tran¬sient behavior of the flame. It was found that, in the case of the Diesel engine, components and coefficients correlate with different combustion modes, i.e. early combustion along the fuel jets and later combustion near the bowl walls. Similar results were obtained from the application of the ICA method to the data col¬lected on PFI SI engine: the deter¬mined independent structures are clearly separated in time and are correlated with the early, median and final luminous combustion