Sonic choking occurs in a pipe system when at some location the gas attempts to accelerate to a velocity faster than the local sonic velocity. Being unable to accelerate any further, the gas reaches its maximum velocity at sonic velocity. Changes to the downstream conditions, such as lowering the pressure, produce no additional flow. In many pipe applications sonic choking is the dominant feature of the system behavior.
Predicting the flow rates under such sonic choking conditions can be very difficult depending on where the choking occurs. AFT Arrow is designed to identify sonic choking and predict the system behavior under such conditions.
Review of Compressible Flow Theory
Compressible Flow Theory in Single Pipes
Role of Pressure Junctions - Detailed Discussion (Long)
Chempak Technical Information - Detailed Discussion
Pipe Material Library References
Subsonic vs. Sonic Pressure Losses
Sonic Choking Detailed Description
Multiple Choking Points in Single Flow Path