Statistically significant data collection and ensemble averaging is achieved as a novel two-color pyrometry (2CP) system – benefiting from improved optical design – is used to acquire a spatially and temporally resolved dataset of reacting n-heptane fuel injections. The results describe soot concentration (KL), soot temperature (T), and the combustion regions for an ensemble of hundreds of single injection pulses and double injections with nominally the same total injected mass. Such a large data set of high pressure/temperature experiments was made possible by a constant pressure flow rig facility, which allows for multiple injection tests to be completed in quick succession. The large dataset ensures that mean values are converged, and variability between injections can effectively be quantified. Single-pulse injections are compared to the two-pulse injections to assess impact on the spatially resolved KL and T contours, combustion timing and locations, as well as soot mass calculations.  The 2CP data for single and two-pulse injections shows that combustion reactions initiated at nominally the same time after start of injection. However, the two-pulse injection had greater combustion recession (reactions occurred further upstream), and wall impingement generally did not occur. Additionally, mean KL was consistently lower throughout time, while mean T peaked at a higher temperature. Two-pulsed injections also produced lower soot mass, indicating that multi-pulse injections strategies may reduce soot production in engines.


Comparing Global Spray Combustion Characteristics and Local Shot-to-Shot Variations in a Reacting N-Heptane Spray

Division / Sponsors: 
Internal Combustion Engine Division (ICED)

Paper Proceedings: https://asmedigitalcollection.asme.org/ICEF/ICEF2020/volume/84034

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