On premixed flame propagation in a curved constant volume channel

The objective of this study is to perform an experimental and numerical investigation of a stoichiometric methane/air premixed flame propagating in a curved constant volume channel. The mixture, initially at rest, had temperature 296 K and pressure 102.65 kPa. In the experimental study, a high speed camera and a pressure sensor captured the evolving flame shape and recorded the temporal pressure history during burning. In the numerical study, the commercial computational fluid dynamics package ANSYS Fluent was used to solve the two dimensional, compressible reacting flow and transport equations for 50 species using the San-Diego combustion mechanism under the same conditions as the experiments. It was found that the premixed flame propagating in the curved and converging channel exhibits different features than previously reported in straight or 90° bend channels. There was a definitive curvature effect on tulip flame development. The conversion of the convex tulip flame back into a concave flame revealed the influence of channel geometry on flame evolution: this conversion does not occur in straight channels. The experiments showed that the rate of pressure change eventually becomes negative mainly due to heat losses which engender correspondingly slower flame propagation during the final stage of the tests. The analysis of the numerical results revealed the effect of the interaction between flame front, pressure field and flame-induced flow on flame evolution during all five stages of flame evolution.