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With the objective of achieving better investigation of engines-fuels by obtaining instantaneous quantitative imaging of in-cylinder processes, several steps have been taken for some years at Rutgers University. They are: (1) Construction of a new multispectral high-speed infrared (IR) digital imaging system; (2) Development of spectrometric analysis methods; (3) Application of the above to real-world in-cylinder engine environments and simple flames. This paper reports some of results from these studies. The one-of-a-kind Rutgers IR imaging system was developed in order to simultaneously capture four geometrically (pixel-to-pixel) identical images in respective spectral bands of IR radiation issued from a combustion chamber at successive instants of time and high frame rates.

In-cylinder flame propagation and its impact on thermal characteristics of the combustion chamber were studied by using a new high-speed spectral infrared imaging system. In this work, successive spectral IR images of combustion chamber events were captured while varying several parameters, including fuel/air, spark timing, speed, and warming-up period. Some investigation of cyclic variation, knock, and high-temperature components during the non-combustion period was also conducted. It was found that the spectral images obtained in both short and long wavelength bands exhibited unique pieces of in-cylinder information, i.e., (qualitative) distributions of temperature and combustion products, respectively. During the combustion period, the temperature of early-formed combustion products continued to increase while the flame front temperature, e.g. near the end gas zone, remained relatively low.