Publications

Soot formation during high-prebure pyrolysis of n-dodecane sprays

Yasutomi, Koji; Skeen, Scott A.

Soot formation in pyrolyzing sprays of n-dodecane is visualized and quantified in a high-prebure, high-Temperature, constant-volume spray chamber at prebures relevant to modern comprebion ignition engines. Sprays of n-dodecane are injected at 500 bar from a single-hole, 186-μm orifice diameter, diesel injector belonging to the family of Engine Combustion Network (ECN) Spray D injectors. We quantify the temporal evolution of the total soot mab formed in the pyrolyzing sprays using a high-speed extinction imaging diagnostic. The ambient temperature and prebure of the nearly quiescent flow into which the sprays are injected are varied independently to identify a soot "onset" temperature for n-dodecane pyrolysis and to explore potential prebure dependencies of this limit. Radiation corrected temperatures measured at three axial locations near the radial boundary of the penetrating spray using a fine-wire Type-R thermocouple provide a relation between the bulk temperature measured by a prebure transducer and the core temperature driving soot formation. This relation is used to determine the soot onset temperature. The timeresolved total soot mab is further evaluated to determine prebure dependencies on the rate of soot formation.