Overview
For these experiments, a conventional, part-load diesel operating point is studied with a pilot-main injection strategy. The piston has a conventional, re-entrant bowl and four valve cutouts (see CFD). The pilot quantity is held constant while the pilot-main energizing dwell (delay between the end of pilot solenoid energizing and the beginning of main solenoid energizing) is varied from 1200 microseconds to 80 microseconds. For each data point, the pilot and main are block-shifted to achieve a point of 50% mass fraction burned between 13 and 14 CAD ATDC. The main injection duration is adjusted to maintain load for this part-load, conventional diesel operating point. Both of the intake port throttles are fully open. Cylinder pressure data are obtained with a titanium piston, whereas the optical data are obtained with a fused silica piston. The table below shows which data are available for each dwell tested.
All imaging is performed through the bottom of the optical piston, which features a conventional, re-entrant bowl and valve cutouts. The complex geometry of the piston introduces distortion in the images. This distortion can be partially corrected with a raytracing-based algorithm, the details of which can be found in the references at the bottom of this page. The distortion correction is based on assumptions about the spatial origin of the measured signal that depend on the type of measurement. Images depicting these assumptions are included in the folders with the imaging data. All of the imaging data available on this website have been distortion corrected, and in some cases background subtracted.
The data files are stored in the .zip files found below. Cylinder pressure-based and injection rate data are available in .xlsx files and should be self-explanatory. Imaging data are stored in binary .mat files (created with MATLAB R2014a). Additional explanations of the data contained in the mat files are available via the “Explanation of data files” links, below. Details of each imaging experiment, including engine operation parameters and experiment settings are stored in .xlsx files in the folders containing each set of measurement results.
The following imaging data are available:
- High-speed Mie scattering data: these images show the liquid fuel injection event with a very high (120 kHz) time resolution. Liquid length evolution has been extracted from this dataset and are also included.
- High-speed natural luminosity (NL) and OH* chemiluminescence data: these images were taken simultaneously with a dual-camera setup. The natural luminosity images show the hot, sooty combustion behavior until approximately 30 CAD ATDC. The OH* chemiluminescence data were taken to provide more information about the combustion of the pilot and the ignition of the main, so the imaging data are available until 6 CAD ATDC. In addition, the natural luminosity images have been processed using combustion image velocimetry techniques to obtain semi-quantitative information about the flow near the piston surface during the mixing-controlled portion of the combustion event. The velocity data are included with the NL data.
Injector clocking for this experiment is as follows:
Experimental results
Intake runner pressure, cylinder pressure, and heat release rates for all dwells
Injection rates for all dwells
Mie scattering images and liquid length for dwells of 300, 140, and 90 microseconds, and for the main-injection-only case
High-speed natural luminosity (NL) images and combustion image velocimetry data for dwells of 1200, 500, 300, 140, and 80 microseconds
High-speed OH* chemiluminescence data for dwells of 1200, 500, 300, 140, and 80 microseconds
References
High-Speed Mie Scattering Imaging
Busch, S., Zha, K., Miles, P.C., “Investigations of Closely Coupled Pilot and Main Injections as a Means to Reduce Combustion Noise,” presented at THIESEL 2014, Valencia, Spain, September 9-12, 2014
Busch, S., Zha, K. and Miles, P. C., “Investigations of closely coupled pilot and main injections as a means to reduce combustion noise in a small-bore direct injection Diesel engine,” International Journal of Engine Research, 16(1):13-22, 2015, DOI: 10.1177/1468087414560776
High-Speed Natural Luminosity Imaging / CIV
Busch, S., Park, C., Warey, A., Pesce, F., Peterson, R., “A Study of the Impact of Pilot-Main Dwell on Late-Cycle Flow in the Piston Bowl of a Light-Duty Optical Diesel Engine,” presented at 12th International Symposium on Combustion Diagnostics, Baden-Baden, Germany, May 10-11, 2016
High-Speed OH* Chemiluminescence Imaging
Park, C., Busch, S., “The influence of pilot injection on high temperature ignition processes and early flame structure in a HSDI diesel engine”, International Journal of Engine Research, 2017, accepted for publication.
Injection Rate Profiles
Busch, S. and Miles, P. C., “Parametric Study of Injection Rates With Solenoid Injectors in an Injection Quantity and Rate Measuring Device,” Journal of Engineering for Gas Turbines and Power, 137(10):101503-101503, 2015, DOI: 10.1115/1.4030095
Busch, S., Zha, K., Miles, P.C., “Investigations of Closely Coupled Pilot and Main Injections as a Means to Reduce Combustion Noise,” presented at THIESEL 2014, Valencia, Spain, September 9-12, 2014
Busch, S., Zha, K. and Miles, P. C., “Investigations of closely coupled pilot and main injections as a means to reduce combustion noise in a small-bore direct injection Diesel engine,” International Journal of Engine Research, 16(1):13-22, 2015, DOI: 10.1177/1468087414560776
Image distortion correction
Busch, S., Zha, K., Miles, P. C., Warey, A., Pesce, F., Peterson, R. and Vassallo, A., “Experimental and Numerical Investigations of Close-Coupled Pilot Injections to Reduce Combustion Noise in a Small-Bore Diesel Engine,” SAE Int. J. Engines 8(2):660-678, 2015, DOI: 10.4271/2015-01-0796