Isentropic Nozzle Choking
Find the maximum isentropic mass flux and distinguish its subsonic and supersonic area branches.
Free theory articleFind the maximum isentropic mass flux and distinguish its subsonic and supersonic area branches.
Concept & interpretation
This module explores isentropic compressible flow of a perfect gas through a nozzle. As flow accelerates through a converging nozzle, the mass flux increases until it reaches a maximum at a Mach number of 1. This phenomenon is known as choking.
Experiment
Use the interactive module to observe how the mass flow and static properties change with the Mach number and stagnation conditions.
- Select a Mach number of 1. Observe that the normalized mass flux reaches its peak of 1.0, and the area ratio is exactly 1.0. This corresponds to the sonic throat.
- Change the Mach number to 0.5. Notice that the branch changes to "Subsonic", the normalized mass flux is lower, and the required area ratio is larger than 1.
- Change the Mach number to 2. Observe that the branch becomes "Supersonic". The required area ratio is again larger than 1, but the static pressure drops significantly below the total pressure.
- Adjust the total pressure to 200000 Pa while keeping Mach at 1, and note the mass flow rate doubles because it is proportional to total pressure.