AN INVESTIGATION ON THERMAL CHARACTERISTICS OF PREMIXED COUNTERFLOW FLAMES USING MICRO-THERMOCOUPLES

Abstract

Hydrogen addition is known to improve the stability of highly strained hydrocarbon premixed flames. Since the flame temperature is an important factor associated with extinction, it is of interest to study the thermal characteristics of the hydrogen-doped flames near extinction. Temperature profiles of highly strained lean-premixed pure CH4 and CH4/H2 flames were measured in a counterflow configuration at strain rates far from and close to extinction. Point temperature measurements were made utilizing a micro-thermocouple probe. To improve the measurements, the thermocouple support design was enhanced and corrections were made for measurement errors where appropriate. Trends observed in experimental and modeling temperature profiles with changes in fuel composition and strain rate, agree favorably. However, there are some discrepancies between the measured and predicted absolute temperatures. Factors contributing to these discrepancies and the methods to reduce the thermocouple measurement errors are discussed.