Page 153 - 48Fundamentals of Compressible Fluid Mechanics

This chapter is under heavy construction. Please ignore. If you want to
contribute and add any results of experiments, to this chapter, please do so.
You can help especially if you have photos showing these effects.

In the previous chapters a simple model describing the flow in nozzle was
explained. In cases where more refined calculations have to carried the gravity or
other forces have to be taken into account. Flow in a vertical or horizontal nozzle
are different because the gravity. The simplified models that suggests them–self
are: friction and adiabatic, isothermal, seem the most applicable. These models
can served as limiting cases for more realistic flow.

The effects of the gravity of the nozzle flow in two models isentropic and
isothermal is analyzed here. The isothermal nozzle model is suitable in cases
where the flow is relatively slow (small Eckert numbers) while as the isentropic
model is more suitable for large Eckert numbers. Insert dimensional analysis,
and point out that Ec num-
ber is relatively small and, for
example, Ec=0.1 is already
The two models produces slightly different equations. The equations re- large number
sults in slightly different conditions for the chocking and different chocking speed.
Moreover, the working equations are also different and this author isn’t aware of
material in the literature which provides any working table for the gravity effect.

115