Hi, As I understand, it is theoretically impossible to have a Mach No. higher than one at the throat of a Convergent Divergent Nozzle. I'm currently working on some calculations, and while i've been told the calculations are correct, I'm getting abnormally high Mach Numbers at the throat. For example, pressure i'm reading at the throat (4.31 Diameter) is 3.3Bar, temperature is 9 degrees celcius. Using Velocity/Speed of Sound, I'm coming away with a Mach Number of over 1.2... I'm assuming it's something to do with Shock Waves, but I really have no knowledge of why?