Schlieren high speed videography

I was having fun shooting quarters with a jet of combusted methane air products. Interesting how the initial shock-wave propagates, and how the jet speed slows down gradually. The initially speed of the jet can be estimated by looking at the images noting the jet tip evolution versus time. It starts at around 300ms, or Mach 0.88 and drops down very quickly to 100m/s and steadily decay.

https://youtu.be/J_XsvjOH78s