From Spark Ignition to Flame Initiation

Kravchik, T.; Sher, Eran; Heywood, John B.

doi:10.1080/00102209508960387

Cited by 54 publications

(31 citation statements)

References 12 publications

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“…For a time period of 100 µs, glow energies of 1.75 mJ, 2.8 mJ, and 5 mJ were given as inputs to the computational model and the results obtained are provided in Figure 50. The results show reasonably good agreement with those presented by Kravchik et al (1995). Increasing energy input results in an increased rate of flame kernel expansion that also can be attributed to higher reaction rates caused by higher temperatures.…”

Section: 3a3 Results (Model 1)supporting

confidence: 81%

“…Power delivered during the glow phase is approximately 30 W. It should be noted that the flame radius is defined in the following results as the region where the temperature is above 1000 K. This threshold was used because high temperature kinetics (flame chemistry) begins to dominate at this temperature. The temperature distribution at different times is shown in Figure 47 for a glow power input of 28 W. Similar to Kravchik et al (1995), the model presented here predicts temperatures ranging from 5500 K to 6500 K near the core of the plasma kernel for a time period of 10 µs to 100 µs. Higher temperatures than those computed by Kravchik et al are shown at a time of 1 µs.…”

Section: 3a3 Results (Model 1)supporting

confidence: 50%

“…As compared to the model by Kravchik et al (1995), the reaction mechanism used is extremely simple, which provides computational simplicity and a reduced computational time burden. The reaction rate for dissociation of nitrogen was taken from Sloane (1990).…”

Section: 3a2 Chemical Kinetics Mechanism and Ionization (Model 1)mentioning

confidence: 99%

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Railplug Ignition System for Enhanced Engine Performance and Reduced Maintenance

Ezekoye¹,

Hall²,

Matthews³

2005

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This Final Technical Report discusses the progress that was made on the experimental and numerical tasks over the duration of this project. The primary objectives of the project were to 1) develop an improved understanding of the spark ignition process, and 2) develop the railplug as an improved ignitor for large bore stationary natural gas engines.We performed fundamental experiments on the physical processes occurring during spark ignition and used the results from these experiments to aid our development of the most complete model of the spark ignition process ever devised. The elements in this model include 1) the dynamic response of the ignition circuit, 2) a chemical kinetics mechanism that is suitable for the reactions that occur in the plasma, 3) conventional flame propagation kinetics, and 4) a multi-dimensional formulation so that bulk flow through the spark gap can be incorporated. This model (i.e., a Fortran code that can be used as a subroutine within an engine modeling code such as KIVA) can be obtained from Prof. Ron Matthews at rdmatt@mail.utexas.edu or Prof. DK Ezekoye at dezekoye@mail.utexas.edu.Fundamental experiments, engine experiments, and modeling tasks were used to help develop the railplug as a new ignitor for large bore natural gas engines. As the result of these studies, we developed a railplug that could extend the Lean Stability Limit (LSL) of an engine operating at full load on natural gas from φ = 0.59 for operation on spark plugs down to φ = 0.53 using railplugs with the same delivered energy (0.7 J). However, this delivered energy would rapidly wear out the spark plug. For a conventional delivered energy (<0.05 J), the LSL is φ = 0.63 for a spark plug. Further, using a permanent magnet to aid the plasma movement, the LSL was extended to φ = 0.54 for a railplug with a delivered energy of only 0.15 J/shot, a typical discharge energy for commercial capacitive discharge ignition systems. Here, it should be noted that railplugs and the associated ignition circuit should not cost much more than a conventional spark ignition system. Additionally, it is believed that the railplug performance can be further improved via continued research and development.iii TABLE OF CONTENTS Abstract iii EXECUTIVE SUMMARYThis Final Technical Report discusses the progress that was made on the experimental and numerical tasks over the duration of this project. The primary objectives of the project were to 1) develop an improved understanding of the spark ignition process, and 2) develop the railplug as an improved ignitor for large bore stationary natural gas engines.Due to these two objectives, the experimental subtasks involved 1) detailed measurements regarding the physical processes occurring during spark ignition, and 2) measurements of the factors that affect railplug performance. Similarly, the modeling subtasks involved developing an improved model for the conventional spark ignition process and developing a model for railplug performance and ignition.The four phases of spark ignition are ...

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Section: 3a3 Results (Model 1)supporting

confidence: 81%

Section: 3a3 Results (Model 1)supporting

confidence: 50%

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Railplug Ignition System for Enhanced Engine Performance and Reduced Maintenance

Ezekoye¹,

Hall²,

Matthews³

2005

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“…In general, the agreement with the experimental data trend is considered to be satisfactory. The calculated radius is also compared with the work of Kravchik et al [3], which was obtained using the PHOENICS and CHEMKIN codes. It can be seen from Fig.…”

Section: Combustion Vessel With Ch 4 -Air Mixturementioning

confidence: 99%

“…Much research has been done to numerically and experimentally study the ignition process [3][4][5]. In engine CFD simulations, it is not practical to resolve the process in detail, because practical numerical grid sizes and time steps are larger 0010 than those needed to describe the early stage of ignition precisely.…”

Section: Introductionmentioning

confidence: 99%