Hi all
I have been studying Coulson & Richardson Volume 1 part 1 chapter 4 (Flow of compressible fluids).
In section 4.6 it talks about shock waves where the Mach number can exceed 1. Unfortunately I have read through this section 3 or 4 times and I do not understand it
This concept seems alien to me and it seems to conflict with earlier chapters which explain how flow through a nozzle/Orifice is maximised when throat velocity is equal to speed of sound in the fluid and the pressure wave cannot propagate upstream any faster (4.2 & 4.3) and also maximum flow through a pipe (4.5) where flow does not increase at outlet pressure below a critical value.
I was always under the thought process that once we hit choked flow - that's it and you cannot increase velocity beyond the speed of sound. (I guess maybe the fluid can continue to expand downstream and the velocity will increase as density drops?)
Is anyone able to explain how we can exceed Mach 1 in simple terms? or do you have any more simplified resources to explain it from the perspective of a chemical engineer interested in pipe flow? I have looked online at some resources from NASA etc; but they are more relating to an object moving through a gas rather than flow of compressible fluids in pipes.
Many thanks in advance