Modelling Pressure vessel in FLUENT 1

[mtaffish]

HI all

I want to know if there is any information on modelling a pressure air vessel.I want to able to know how long it will take for the pressure to decrease to the atmospheric pressure through an outlet.

thx

 

[btrueblood]

Why would you use something as complex as Fluent for this calculation?

 

[mtaffish]

btrueblood

Well i looked into some fluid mechanics books and found thats most equations assume incompressible flow so , but do you have any information on how to do this uwing fluid mechanics basics

thx

 

[btrueblood]

"Blowdown" of an air-filled pressure vessel, assuming compressible, supersonic- or subsonic-flow, or incompressible subsonic flow, are elementary problems. I've even modelled the free-molecular flow regime for this type of problem, and found excellent agreement to test results (pump-down of a vacuum vessel).

This type of problem is typically dealt with in the examples in most fluid mechanics flow texts. The basic assumption is that the outlet flow area is much smaller than the tank cross section. Calculate the flow rate through the outlet area as a function of upstream pressures, construct differential equation of tank conditions (P, T) use known starting volume/pressure/temp. of vessel to provide an initial condition. Integrate, numerically or classically, to find time when tank pressure drops to ambient.

 

[mohnos]

I need an elliptical pressure vessel volume calculations

 

[btrueblood]

You mean ellipsoidal?

Volume of an ellipsoid = (4/3)(pi)abc

where a b and c are the lengths of the semiaxes.