Spectral IR Images of Direct-Injection Diesel Combustion by High-Pressure Fuel Injection 950605

Instantaneous successive spectral infrared (IR) images were obtained from a spray plume in a direct injection (DI) type compression-ignition (CI) engine during the compression and combustion periods. The engine equipped with a high pressure electronic-controlled fuel injector system was operated by using D-2 Diesel fuel.
In the new imaging system used for the present study, four high-speed IR cameras (with respective band filters in front) were lined up to a single optical arrangement containing three spectral beam splitters to obtain four spectral images at once. Two band filters were used for imaging the water vapor distribution and another two band filters were placed for capturing images of combustion chamber wall or soot formation.
The simultaneous imaging was successively triggered by signals from an encoder connected to the engine. The fuel injection parameters were precisely controlled and the pressure-time (p-t) history was obtained for individual sets of images. The start of fuel injection was varied through four different crank angle positions.
Mentioning some results from the study, the spectral IR images had no resemblance with the ones obtained using a visible-range camera from a comparable engine system as reported by others. In general, the present spectral images taken at the same crank angle were not mutually comparable.
A highly unexpected phenomenon was observed in the study, i.e., the images recorded during the ignition delay period exhibit some strong preflame reactions over the fuel spray plume. The preflame reactions appear to have started immediately after the fuel injection. This newly observed phenomenon is interpreted to represent strong chemiluminescence seemingly followed by exothermic reactions. The heat release during the ignition delay period is expected to be offset by the latent heat of evaporation to cause no measurable change in p-t history compared with the same measured from a hot-motoring condition.


Subscribers can view annotate, and download all of SAE's content. Learn More »


Members save up to 16% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:

Optical Investigation of Injection and Combustion Phases of a Fouled Piezoelectric Injector in a Transparent CR Diesel Engine


View Details


Study on the Double Injection Strategy of Gasoline Partially Premixed Combustion under a Light-Duty Optical Engine


View Details


Effects of High-Pressure Fuel Injection and a Micro-Hole Nozzle on Combustion in a Rapid Compression Machine


View Details