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Next: Rigid Tank with Nozzle Up: General Model and Non-dimensioned Previous: Isothermal Process in The   Index

## A Note on the Entrance Mach number

The value of Mach number, is a function of the resistance, and the ratio of pressure in the tank to the back pressure, . The exit pressure, is different from in some situations. As it was shown before, once the flow became choked the Mach number, is only a function of the resistance, . These statements are correct for both Fanno flow and the Isothermal flow models. The method outlined in Chapters 8 and 9 is appropriate for solving for entrance Mach number, .

Two equations must be solved for the Mach numbers at the duct entrance and exit when the flow is in a chokeless condition. These equations are combinations of the momentum and energy equations in terms of the Mach numbers. The characteristic equations for Fanno flow (9.50), are

and

where is defined by equation (9.49).

The solution of equations (11.18) and (11.19) for given and yields the entrance and exit Mach numbers. See advance topic about approximate solution for large resistance, or small entrance Mach number, .

Next: Rigid Tank with Nozzle Up: General Model and Non-dimensioned Previous: Isothermal Process in The   Index
Created by:Genick Bar-Meir, Ph.D.
On: 2007-11-21