235
Views
28
CrossRef citations to date
0
Altmetric
Original Articles

LIF MEASUREMENTS AND CHEMICAL KINETIC ANALYSIS OF NITRIC OXIDE FORMATION IN HIGH-PRESSURE COUNTERFLOW PARTIALLY PREMIXED AND NONPREMIXED FLAMES

&
Pages 1809-1853 | Received 01 Jul 2003, Accepted 01 Mar 2004, Published online: 11 Aug 2010
 

Abstract

We report quantitative, spatially resolved, linear laser-induced fluorescence (LIF) measurements of nitric oxide concentration ([NO]) in laminar, methane/air counterflow partially premixed and nonpremixed flames at six pressures up to 15 atm using excitation near 226.03 nm in the γ(0,0) band of NO. For partially premixed flames, fuel-side equivalence ratios (φB) of 1.45, 1.6, and 2.0 are studied at a global strain rate of 20 s−1. For nonpremixed flames, a complete set of NO measurements at global strain rates of 20 s−1, 30 s−1, and 40 s−1 is presented to supplement previously reported data in such flames. The quantitative NO measurements are compared with predictions from an opposed-flow flame code utilizing two GRI chemical kinetic mechanisms (versions 2.11 and 3.0). The effect of radiative heat loss on NO predictions is assessed by using a modified version of the code that considers radiation in the optically thin limit. The linear LIF measurements of [NO] are corrected for variations in the electronic quenching rate coefficient by using major species and temperature profiles generated by the opposed-flow flame code plus quenching cross sections for NO available from the literature.

A pathway analysis provides the relative contribution of different NO formation mechanisms to the total amount of NO produced at various pressures. Quantitative reaction path diagrams are used to investigate pictorially species interactions during NO formation. Finally, we identify key reactions controlling NO concentrations in counterflow partially premixed and nonpremixed flames by using a sensitivity analysis. For the nonpremixed flames, NO measurements at pressures of 2–5 atm disagree substantially with predictions from either GRI mechanism. On the other hand, both mechanisms predict observed NO concentrations reasonably well beyond 6 atm. In general, for our nonpremixed flames, NO formation is dominated by the prompt route at lower pressures with an increasing contribution from the N2O pathway at higher pressures. For partially premixed flames, GRI 3.0 mimics the basic quantitative trends found in our LIF measurements at 1–15 atm. The kinetic analysis indicates that the prompt mechanism dominates at lower pressures, whereas the thermal and N2O pathways become more important at higher pressures. At any given pressure, a reduction in partial premixing results in kinetic behavior approaching that of the nonpremixed flames.

Notes

1All reaction numbers refer to the GRI mechanisms (versions 2.11 and 3.0).

Log in via your institution

Log in to Taylor & Francis Online

PDF download + Online access

  • 48 hours access to article PDF & online version
  • Article PDF can be downloaded
  • Article PDF can be printed
USD 61.00 Add to cart

Issue Purchase

  • 30 days online access to complete issue
  • Article PDFs can be downloaded
  • Article PDFs can be printed
USD 1,493.00 Add to cart

* Local tax will be added as applicable

Related Research

People also read lists articles that other readers of this article have read.

Recommended articles lists articles that we recommend and is powered by our AI driven recommendation engine.

Cited by lists all citing articles based on Crossref citations.
Articles with the Crossref icon will open in a new tab.