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Title: Turbulent combustion of premixed flames in closed vessels

An extensive series of experiments on spark-ignited explosion of propane-air mixtures in both turbulent and quiescent conditions in a cubic closed vessel is described. Turbulence was produced by a moving grid, and the development with time of pressure and of flame area (from light emission) recorded. The effects of grid-hole diameter, grid velocity, spark timing after passage of the grid, equivalence ratio, and initial pressure were investigated. Estimates of the rate of strain in the unburnt gases were derived from hot-wire anemometry. Results indicated that rate of strain was a major factor governing the rate of combustion. Theoretical simulations of explosions with a simple model were made, in which turbulence was characterized solely by the rate of strain, and in which the decay of turbulence during explosions and the effect of changes in pressure on both burning velocity and flow field were taken into account. The simulations were compared with experimental results, and reinforced the idea that turbulence has the dual effect of causing wrinkling of flames and, especially for weaker mixtures, reducing the burning velocity. An empirical relationship was found in which the logarithmic rate of wrinkling was proportional to the square root of the rate of strain. Somemore » simple conclusions are drawn regarding practical application of the results.« less
Authors:
 [1] ;  [2]
  1. (Univ. of Alberta, Edmonton (Canada). Mechanical Engineering)
  2. (Univ. of Liverpool (United Kingdom). Mechanical Engineering)
Publication Date:
OSTI Identifier:
5211098
Resource Type:
Journal Article
Resource Relation:
Journal Name: Combustion and Flame; (United States); Journal Volume: 96:4
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; 33 ADVANCED PROPULSION SYSTEMS; PROPANE; COMBUSTION KINETICS; SPARK IGNITION ENGINES; MATHEMATICAL MODELS; TURBULENT FLOW; ALKANES; CHEMICAL REACTION KINETICS; ENGINES; FLUID FLOW; HEAT ENGINES; HYDROCARBONS; INTERNAL COMBUSTION ENGINES; KINETICS; ORGANIC COMPOUNDS; REACTION KINETICS 034000* -- Natural Gas-- Combustion; 330101 -- Internal Combustion Engines-- Spark-Ignition