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Supersonic Branch

In Chapter (8) it was shown that the isothermal model cannot describe adequately the situation because the thermal entry length is relatively large compared to the pipe length and the heat transfer is not sufficient to maintain constant temperature. In the Fanno model there is no heat transfer, and, furthermore, because the very limited amount of heat transformed it is closer to an adiabatic flow. The only limitation of the model is its uniform velocity (assuming parabolic flow for laminar and different profile for turbulent flow.). The information from the wall to the tube center^9.6 is slower in reality. However, experiments from many starting with 1938 work by Frossel^9.7has shown that the error is not significant. Nevertheless, the comparison with reality shows that heat transfer cause changes to the flow and they need/should to be expected. These changes include the choking point at lower Mach number.

Next: Maximum Length for the Up: Fanno Flow Previous: Examples of Fanno Flow Index

Created by:Genick Bar-Meir, Ph.D.
On: 2007-11-21