|
Introduction of spectrophotometric methods into engine research considerably expands diagnostic possibilities of the work cycle in the internal combustion engine. Spectral analysis enables to determine concentrations of chemically active compounds - radicals, which are temporary present in the flame and do not constitute finał products of the combustion. The aim of the presented research was to investigate spectral properties of the combustion flame with special regard to the detection and estimation of intensity of knocking combustion. Research was made using modifled single cylinder si test engine equipped with an optical sensor having direct access to the combustion chamber. The sensor enabled on-line transmission of the transient optical signal during the combustion through the bundle of optical wave-guides. Measurements were based on the chemiluminescence phenomena occurring in the combustion flame under the influence of high temperature and pressure. Gathered signal was passed to the monochromator. Spectral recordings were done for wavelengths typical of emission of intermediate products, covering the range from 250 nm to 625 nm, including investigated radicals like C2, CH, CN, OH. Obtained results confirmed, that occurrence of knock can be precisely detected on the basis of signal analysis which was recorded for chemiluminescence traces of different radicals. Comparison with in parallel recorded indicated pressure have shown that characteristics of emitted spectra remain in good conformity and are more sensitive to the changing of engine operating conditions.
|
