Relationship Between Diesel Fuel Spray Vapor Penetration/Dispersion and Local Fuel Mixture Fraction

Diesel spray experiments at controlled high-temperature and high-pressure conditions offer the potential for an improved understanding of diesel combustion, and for the development of more accurate CFD models that will ultimately be used to improve engine design. Several spray chamber facilities capable of high-temperature, high-pressure conditions typical of engine combustion have been developed, but uncertainties about their operation exist because of the uniqueness of each facility. For the IMEM meeting, we describe results from comparative studies using constant-volume vessels at Sandia National Laboratories and IFP. Targeting the same ambient gas conditions (900 K, 60 bar, 22.8 kg/m{sup 3}, 15% oxygen) and sharing the same injector (common rail, 1500 bar, KS1.5/86 nozzle, 0.090 mm orifice diameter, n-dodecane, 363 K), we describe detailed measurements of the temperature and pressure boundary conditions at each facility, followed by observations of spray penetration, ignition, and combustion using high-speed imaging. Performing experiments at the same high-temperature, high-pressure operating conditions is an objective of the Engine Combustion Network (http://www.ca.sandia.gov/ECN/), which seeks to leverage the research capabilities and advanced diagnostics of all participants in the ECN. We expect that this effort will generate a high-quality dataset to be used for advanced computational model development at engine conditions.

Comparison of Diesel Spray Combustion in Different High-Temperature, High-Pressure Facilities

Sprays are among the most intellectually challenging and practically important topics in fluid mechanics. This paper reviews needs, milestones, challenges, and a broad array of techniques for spray measurement. In addition, tabular summaries provide cross-referenced entry points to the vast literature by organizing over 300 citations according to key spray phenomena, physical parameters and measurement techniques for each of the principal spray regions (nozzle internal flow, near-field spray-formation region, far-field developed spray, and spray-wall interaction). The article closes with perspectives on some current issues in spray research, including the cost and complexity of apparatus for spray physics and spray engineering, the need for simultaneous diagnostic measurements under application-relevant conditions, and the effective comparison of spray measurements and numerical simulations.

https://iopscience.iop.org/article/10.1088/0957-0233/26/1/012002/pdf

Spray measurement technology: a review

Experimental characterization of diesel ignition and lift-off length using a single-hole ECN injector

To investigate the effects of oxygenated biofuels on soot formation, oxidation, and distribution, a detailed comparative study using the forward illumination light extinction method was conducted in an optical constant volume combustion chamber. Various ambient temperatures (800 and 1000 K) and ambient oxygen concentrations (21, 16, and 10.5%) were investigated to mimic both conventional diesel combustion and low-temperature combustion conditions. Five oxygenated biofuels were used, including neat soybean biodiesel S100, neat butanol B100, and three alcohol–biodiesel blends that contained by volume 20% ethanol E20S80, 20% butanol B20S80, and 50% butanol B50S50. It is found that the composition of the biofuel has a larger effect on soot suppression efficiency at 800 K ambient temperature than that at 1000 K. Soot distribution is observed at larger distances from the injector, and less soot is located near the wall region with the additional oxygen content of biofuels at 21% ambient oxygen concentration. Wi...

Soot Emissions of Various Oxygenated Biofuels in Conventional Diesel Combustion and Low-Temperature Combustion Conditions

This paper first compares strengths and weaknesses of different options for performing optical diagnostics on HD diesel sprays. Then, practical experiences are described with the design and operation of a constant volume test cell over a period of more than five years. In this test rig, pre-combustion of a lean gas mixture is used to generate realistic gas mixture conditions prior to fuel injection. Spray growth, vaporization are studied using Schlieren and Mie scattering experiments. The Schlieren set-up is also used for registration of light emitted by the combustion process; this can also provide information on ignition delay and on soot lift-off length. The paper further describes difficulties encountered with image processing and suggests methods on how to deal with them. Results are presented that illustrate the wide range of capabilities of this test-rig when combined with high speed video registration, in particular its potential for studying issues related to vaporizing fuel spray dynamics.

http://www.mate.tue.nl/mate/pdfs/10123.pdf

Wout de Boer

Papers

Design and operation of a high pressure, high temperature cell for HD diesel spray diagnostics: guidelines and results