I am confused about the relation of mass flow rate with different mach numbers in a compressible flow. In wikipedia (http://en.wikipedia.org/wiki/Choked_flow), I read the following: "Although the gas velocity reaches a maximum and becomes choked, the mass flow rate is not choked. The mass flow rate can still be increased if the upstream pressure is increased as this increases the density of the gas entering the orifice." This makes me think that: - The maximum velocity will be mach 1 and won't increase (at the minimum tube area, or throat) - The mass flow rate will not be limited, because the higher the pressure, the higher the density, so mass flow rate will increase (mdot = mach1 * A * rho). But then I read from nasa (http://www.grc.nasa.gov/WWW/k-12/airplane/mflchk.html): "There is a maximum airflow limit that occurs when the Mach number is equal to one. The limiting of the mass flow rate is called choking of the flow." And: "If we have a tube with changing area, like the nozzle shown on the slide, the maximum mass flow rate through the system occurs when the flow is choked at the smallest area." This seems contradictory. I might be missing something.