Numerical Simulations of Ozone Addition to Strained Flames

ABSTRACT

Due to its capacity to promote the flame speed of a mixture, ozone addition to freely-propagating flames has been investigated over a variety of conditions. Nonetheless, the understanding of how ozone addition enhances strained flames is limited. In the present study, numerical simulations are conducted in the counterflow twin premixed flame configuration to explore the effects of ozone addition on strained laminar flames. It is seen that ozone addition can cause difficulties in the extrapolation of the flame speed based on the local minimum velocity. However, the enhancement by ozone of the strained flame speed based on the point of maximum heat release rate rises consistently as the strain rate increases and accelerates as the extinction limit approaches. A major reason for this occurrence is that almost all of the most sensitive reactions are promoted more by ozone under higher strain rates. An investigation into the ozone consumption pathways is also conducted, and it is found that increased pressures and temperatures favor the ozone decomposition reaction and ozonolysis reactions over the ozone hydrogen-abstraction reaction. It is also seen that extended residence times decrease the sensitivity coefficients of ozonolysis reactions for strained flames but promote their sensitivity coefficients for freely-propagating flames, which is attributed to the differences in adiabaticity between the two.

KEYWORDS:

• Ozone
• counterflow premixed flame
• laminar flame speed
• extinction limit
• ozonolysis reactions

Acknowledgments

This research was performed while C. B. Reuter held a National Research Council (NRC) Research Associateship Award at the Air Force Research Laboratory.

Declaration of Competing Interest

None

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website.

Additional information

Funding

This research was performed while C. B. Reuter held a National Research Council (NRC) Research Associateship Award at the Air Force Research Laboratory.