Time-resolved 3D investigation of the ignition process of a methane diffusion impinging flame

• A methane diffusion impinging flame was studied during ignition experimentally.
• Flames in blue and yellow colour are identified and analysed seperately.
• The flame is blue colour dominated from ignition to 120 ms.
• The evolution of blue flame 3D structure correlates with fuel/air mixing conditions.
• The yellow flame development in space has been analysed.

The ignition process of a methane diffusion impinging flame was investigated experimentally, using high speed schlieren/stereo imaging and image processing techniques. Two types of flame can be identified during the ignition process: premixed like flame with weak blue colour and diffusion flame with yellow-reddish colour. The 3D structure of blue flame after enhancement and yellow flame has been reconstructed and analysed seperately. The ratio between green and blue colour intensity is used to provide indications of the global fuel/air mixture state of the blue flame, which is found to correlate well with the flow conditions and flame propagation characteristics.