Numerical Simulations of Low Temperature Ignition Chemistry with Flow, Temperature, and Species Fluctuations in High Pressure Counterflow Flames

Shan, Fanli; Piao, Yun-Song; Dooley, Stephen; Ju, Yiguang

doi:10.2514/6.2012-168

Cited by 1 publication

(1 citation statement)

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“…However, only a few studies focused on the NTC characteristics manifested by the transient ignition process of large hydrocarbon fuels in non-premixed counterflow. For nonpremixed n-heptane/air counterflow, Liu et al 12 investigated the transient ignition process below, within and above the NTC regime; Shan et al 19 examined the effects of H 2 O 2 concentration and strain rate perturbations on low-temperature and high-temperature ignition processes. In non-premixed counterflow, the NTC characteristics are expected to be dominated by both kinetics (including low-and hightemperature chemistries) and transport, which are affected by different factors including strain rate, fuel/air temperature, and pressure.…”

Section: Introductionmentioning

confidence: 99%

A Computational Study on the Transient Ignition and NTC Behavior of Non-Premixed Dimethyl Ether/Air Counterflow under Elevated Pressure

Wang

Lee

et al. 2020

Energy Fuels

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For large hydrocarbon fuels with low-temperature chemistry, the non-premixed ignition and negative temperature coefficient (NTC) are affected by the coupling effects of chemical kinetics and transport. In this study, the transient non-premixed ignition process in dimethyl ether (DME)/air counterflow at low temperature and elevated pressure is studied numerically with detailed chemistry and transport. The emphasis is on the effects of strain rate, fuel/air temperature, and pressure on the nonpremixed ignition and the corresponding NTC characteristics. Similar to homogeneous ignition, the non-premixed ignition process consists of three stages, which are dominated by low-, intermediate-, and high-temperature chemistries, respectively. Multiple reaction zones are identified in these ignition stages. An increase in strain rate and a decrease in fuel temperature are both found to greatly inhibit the intermediate-temperature ignition stage while only marginally affecting the low-and high-temperature ignition stages. As a result, the non-premixed NTC behavior manifested by the global ignition delay time is reduced by either increasing the strain rate or decreasing the fuel temperature. However, while an increase of the strain rate greatly enhances the inhibitive effect of transport on the intermediate-temperature ignition stage, change of the fuel temperature has a minor influence on the reaction− transport interaction during the ignition process. Besides, by significantly promoting the kinetic effect over the transport effect, elevation of pressure greatly accelerates the intermediate-temperature ignition stage and weakens the inhibitive effect of increasing strain rate on the non-premixed ignition and the corresponding NTC behavior.

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Section: Introductionmentioning

confidence: 99%