Events Calendar

AME Department Seminar

Speaker: Sandro Gomez , Professor, Yale University

Talk Title: Highly Turbulent Strained Premixed Flames in the Distributed Reaction Regime

Abstract: Turbulent lean-to-stoichiometric premixed flames were experimentally studied in a counterflow configuration at turbulent Reynolds numbers on the order of one thousand. The primary objective is to examine conditions of departure from the flamelet regime and analyze the turbulent premixed flame structure under conditions in which disrupted and locally-extinguished flame fronts are expected.

A turbulent stream of fresh premixed reactants was opposed to a second stream of hot products of combustion. By varying temperature and composition of the combustion product stream, the “realities” of practical flames, such as heat losses and composition stratification, could be studied systematically in a well-defined system. These effects are not accounted for by the commonly used Borghi diagram of regimes of turbulent premixed combustion. Diagnostic techniques included PIV and simultaneous CO/OH-LIF to probe the structure of the oxidation layer.

It was found that the boundary between the flamelet regime and the distributed reaction zone was lowered significantly to turbulent Karlovitz numbers, Kat, of unity order. The oxidation layer was found to be sensitive to the turbulence intensity and the hot product composition. In fact, the quenching of the oxidation layer, that is not currently accounted for in turbulent combustion models, appeared to be a critical element of departure from the flamelet regime.

The interpretation of the experimental results was aided by ancillary numerical calculations of strained laminar premixed flames that showed two distinct extinction modes, an abrupt one and a smooth one, the latter being favored by an excess of oxidizing species in the combustion product stream.

The highly turbulent opposed jet system is shown to offer several advantages by comparison with the more common jet flames and is proposed as a benchmark for turbulent combustion studies.


Host: Prof. P. Ronney

More Info: http://ame-www.usc.edu/seminars/index.shtml#upcoming

Location: Seaver Science Library (SSL) - 150

Audiences: Everyone Is Invited

Contact: April Mundy

Event Link: http://ame-www.usc.edu/seminars/index.shtml#upcoming