I'm currently conducting an experiment in an optical engine and capturing images using a high-speed camera. The primary objective is to determine the flame speed under various experimental conditions using the change rate of flame area.
The process involves analyzing a series of high-speed camera images to track the evolution of the flame front over time. I'm looking for insights or methodologies that could help in accurately calculating the flame speed.
The first most basic part of this is establishing your time base.
You say you have a high speed camera. What is the frame rate? Your time base will be one over whatever the frame rate is. i.e. if my frame rate is 5000 frames per second, then my time base is 1/5000 or 0.0002 seconds per frame. So, each sequential image will be 0.0002 seconds apart in time.
The next issue will be to figure out the dimensions are within the cylinder. If you are really good, you can figure this out mathematically, me, 25 years ago I put the circular equivalent of a ruler inside my engine, assembled everything and took a picture of the scale. I then used that scale as an overlay to measure fuel injection penetration and flame kernel growth between frames to judge both total penetration and fuel and flame front velocities.
So, say you measure a 0.1cm difference in flame front location between two frames. This works out to be 0.1cm/0.0002sec = 500 cm/sec or 5 m/s flame front velocity.
Whether you are coming down from the top of in from the side you may use this approach.
Depending on your equipment and amount of data you gather, you can start to estimate flame area and volume, that more involves integration and sometimes some clever transforms.
Good Luck and Have Fun
Paul
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