water vapour properties
 

hi all i am modelling the steam flow though converging diverging nozzle. Pocess parameter are inlet condition pressure 41 bar and saturated steam outlet condotion 15 bar density variation as ideal gas it is expected that there will be chock flow at throat. During post processing i found that the density which fluent consider is much lower that the density from steam table. because of above reasn i am getting less flow rate . Please impart information relatted to above topic thanks a lot.

Re: water vapour properties
 

What are you using to calculate your density? If you are using ideal gas then it is likely obvious since steam tables represent another "model" of steam hich may not be ideal under your conditions.Since steam table data is experimental you should believe more in them. Have you checked whether ideal gas predictions match with steam table data?

Swarup

Re: water vapour properties
 

hi Swarup thanks foe your relpy You have understood my problem . See my pressure difference is more so i can not use the density as a constant, so i have given density variation as a ideal gas but the idea as gas density is less then steam table. I would like to know which model or UDF i should use to predict variation properties nearer to steam stable. second problem i faced ,i used WET STEAM in fluent 6.2 which predicts properties same as steam table but but this model is available for only couple solver . and when i used this model for my problen it gave error as memory is not sufficient . i want to know if there is any way to increase the memory allocation in fluent thanks once again

Re: water vapour properties
 

A solution would perhaps be a UDF that returns the density as corresponding to the steam table (i.e. a fitted curve)?

/Henrik

Re: water vapour properties
 

Maybe the steam tables you are referring to are not correct . try this link

http://www.lulu.com/content/278487

It has steam tables you can view online for free