skip to main content

Title: Measurements of fuel mixture fraction oscillations of a turbulent jet non-premixed flame

This work describes new type of combustion instability for which the 3-way coupling between mixing, flame heat release, and acoustics is modified by local buoyancy effects. Measurements of fuel mixture fraction are made for a non-premixed jet flame in a combustion chamber to assess the dynamics of mixing under imposed acoustic oscillations (22-55 Hz). Infrared laser absorption and phase resolved acetone-planar laser induced fluorescence are used to measure the fuel mixture fraction and then the degree of fuel/air mixing is calculated by determining the unmixedness. Results show acoustic excitation causes oscillations in the degree of fuel/air mixing at the driving frequency, which results in oscillatory flame behavior. This oscillatory flame behavior couples to the buoyancy and this in turn affects the mixing. Results also show that the mixing becomes less effective when the excitation frequency is increased or when the flame is present, compared to the non-reacting case. This work describes a key coupling mechanism that occurs when buoyancy is a significant factor in the flow field. (author)
Authors:
 [1] ; ;  [2] ;  [3]
  1. LG Chem Research Park, Dajeon 305-380 (Korea)
  2. Department of Mechanical Engineering, California Institute of Technology, Pasadena, CA 91125 (United States)
  3. Department of Mechanical and Industrial Engineering, University of Iowa, Iowa City, IA 52242 (United States)
Publication Date:
OSTI Identifier:
21227386
Resource Type:
Journal Article
Resource Relation:
Journal Name: Combustion and Flame; Journal Volume: 156; Journal Issue: 1; Other Information: Elsevier Ltd. All rights reserved
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; MIXTURES; FLAMES; AIR; FUELS; MIXING; OSCILLATIONS; EXCITATION; JETS; COMBUSTION INSTABILITY; COUPLING; HEAT LOSSES; COMBUSTION CHAMBERS; ACOUSTICS; HZ RANGE; FREQUENCY DEPENDENCE