Development and mixing of Diesel sprays are long known to be key factors for combustion and pollutant
emissions but the related measurements in a real engine is not an easy task. This fact led researchers
to simulate engine conditions in special facilities that allow the use of high-fidelity diagnostics. The
Engine Combustion Network (ECN) has focused on overcoming the variability from one institution
to the next by testing nominally identical Diesel injectors in four different facilities for the first time,
including constant-pressure flow and constant-volume preburn chambers. Liquid- and vapor-phase
penetration, ignition delay, and lift-off length measurements are compared with similar experimental
setups and processing methodologies. The consistency of the data obtained indicates a good level of repeatability
between the test rigs employed, and no deviation of the results can be associated with the
facility type. Comparison of liquid length measurements via Mie scattering shows that this diagnostic
is sensitive to the orientation of the light source. For more repeatable results between facilities, diffused
back-illumination imaging is recommended. A novel image processing method has been employed to
detect spray boundaries obtained in high-speed schlieren imaging: the method showed high accuracy
and robustness to the different schlieren setups employed by the institutions. High-speed broadband
chemiluminescence, as schlieren imaging, shows the onset of cool flame, and moreover when the combustion
is stabilized, it provides an important reference to define ignition delay and lift-off length. The
methodology put in place by the ECN participants in this work allows an important step forward in
two directions. The first is to understand the repeatability related to experimental data in high-pressure,
high-temperature environments. The second is to advance the understanding of the different diagnostics
applied, thereby providing more quantitative measurements that yield to a more suitable datasets
for computational fluid-dynamic model evaluation.Bardi, M.; Payri Marín, R.; Malbec, LM.; Bruneaux, G.; Pickett, LM.; Manin, J.; Bazyn, T.... (2012). Engine combustion network: comparison of spray development, vaporization, and combustion in different combustion vessels. Atomization and Sprays. 22(10):807-842. doi:10.1615/AtomizSpr.2013005837S807842221
