Investigation of Combustion in High Speed Direct Injection Diesel Engines Using a Novel High Speed Combustion Photography Technique

The paper reports on investigations carried out on a modern single cylinder high speed direct injection diesel engine (0.5 liter displ.) by means of a novel combustion photography technique. The novelty consists in using especially designed windows and endoscopes providing optical access into the combustion chamber. Due to the minuteness of the optical components they can be mounted in the cylinder head in a similar way as is common practice with cylinder pressure transducers. Thus, combustion may be watched "with the eye on the cylinder head fire deck". Illumination of fuel sprays is provided by a flash bulb positioned behind a second window. In order to support the evaluation of the combustion phenomena recorded on the high speed movie, they are supplemented by data on injector needle lift, injection pressure, cylinder pressure, etc., all being recorded by the AVL Digital Analyzer synchronized to the photographic system. Results are presented on spray formation, flame development and bulk movement, radiation intensity, associated rate of heat release etc. for different combustion system parameters.