178. CRITICAL LIMITS OF EXTINCTION AND AUTOIGNITION IN DIMETHYL ETHER / AIR FLAMES IN THE COUNTERFLOW CONFIGURATION

Department: Mechanical & Aerospace Engineering
Faculty Advisor(s): Kalyanasundaram Seshadri

Primary Student
Name: Ryan Kyle Gehmlich
Email: rgehmlic@ucsd.edu
Phone: 858-534-6505
Grad Year: 2013

Abstract
A numerical and experimental investigation is carried out to characterize the critical limits of extinction and autoignition of dimethyl ether (DME)/air flames in a counterflow burner. The fuel stream consists of a diluted stream of dimethyl ether, at mass fractions ranging from 0.15-0.40. The oxidizer stream consists of air. The two counterflowing streams are momentum balanced such that the stagnation plane rests at the midpoint between the two ducts. Numerical calculations corresponding to the experimental conditions are performed using a chemical mechanism developed for DME at Lawrence Livermore National Laboratory which consists of 79 species and 351 reversible reactions. This detailed mechanism is reduced to a skeletal mechanism composed of 47 species and 215 reversible reactions. An additional mechanism is proposed as a good candidate for the development of model surrogates for renewable jet fuels which combines the proposed skeletal DME mechanism with a more general mechanism published by Narayanaswamy et al., and which has been used successfully for the simulation of high temperature oxidation of a wide variety of hydrocarbons. All three mechanisms predict the critical limits of extinction very well. All three mechanisms also predict the autoignition limits within the bounds of experimental uncertainty.

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