Browsing by Subject "Ignition Delay"

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    A Characterization of Different Spark Regimes for Ignition Delay Comparison with Conventional Spark Plugs
    (Office of the Vice Chancellor for Research, 2016-04-08) Wozniak, Zachary M.; Burton, Jesse C.; Hedrick, Cameron J.; Deng, Qiuyu; Robinson, Daniel W.
    The introduction of plasma into combustion and ignition processes has continuously proved to be advantageous when compared to the conventional spark ignition in a wide range of categories. From the capability to ignite leaner mixtures and improve fuel economy to an effective reduction of hazardous emissions and ignition delay, the benefits of integrating non-equilibrium plasma can be utilized for numerous applications including hot jet ignition. Detailed design specifications for the electrode configuration, circuit schematic, and combustion rig are developed and presented. Using a CCD camera and high performance oscilloscope, this paper aims to identify, characterize, and compare the different effects of frequency and pulse width of a driver circuit on the plasma sparks quantitatively in terms of the current, voltage, and energy attributes. Four different plasma regimes are investigated with frequencies ranging from 5.44 Hz to 95.46 kHz and pulse energies ranging from 168 μJ to 14.42 J. The maximum voltage and current characteristics of the plasmas indicate a glow discharge referencing previous experiments. Future work is laid out for a comparison of the ignition progression between a non-thermal plasma system and a traditional spark with using Schlieren imaging.
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    Hot jet ignition delay characterization of methane and hydrogen at elevated temperatures
    (Pro Quest, 2017-08) Kojok, Ali Tarraf; Nalim, M. Razi; Larriba-Andaluz, Carlos; Zhu, Likhun
    This study contributes to a better understanding of ignition by hot combustion gases which finds application in internal combustion chambers with pre-chamber ignition as well as in wave rotor engine applications. The experimental apparatus consists of two combustion chambers: a pre chamber that generates the transient hot jet of gas and a main chamber which contains the main fuel air blend under study. Variables considered are three fuel mixtures (Hydrogen, Methane, 50\% Hydrogen-Methane), initial pressure in the pre-chamber ranging from 1 to 2 atm, equivalence ratio of the fuel air mixture in the main combustion chamber ranging from 0.4 to 1.5, and initial temperature of the main combustion chamber mixture ranging from 297 K to 500 K. Experimental data makes use of 4 pressure sensors with a recorded sampling rate up to 300 kHz, as well as high speed Schlieren imaging with a recorded frame rate up to 20,833 frame per seconds. Results shows an overall increase in ignition delay with increasing equivalence ratio. High temperature of the main chamber blend was found not to affect hot jet ignition delay considerably. Physical mixing effects, and density of the main chamber mixture have a greater effect on hot jet ignition delay.