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satish March 5, 2008 14:56

how to give pressure as an input in spray modeling
 
hi, enybody who is working on spray modeling pls help me.

in the spray modeling for injection definition how to give injection pressure as an input parameter if i know the hole diameter and input pressure instead of mass flow rate? how to find the cone angle for the different injection pressure?

thanks and regards, satish

Andrea March 7, 2008 21:23

Re: how to give pressure as an input in spray mode
 
Hi
to model an injectio you really need to know the mass flow rate. if you know the pressure difference across your injector you can calculate the injection velocity (teorically). Then if you refer to the density of the liquid at your injection temperature you can calculate your mass flow rate, if you suppose a discarghe coeff. and you know the injector diameter. Even if you could define only the pressure difference, you need to suppose a discarghe coeff...so the first way is not so different for this second one.
With my experiment I've seen that Star calculate the injection velocity with reference on mass flow rate and geometrical data only...the effective injection velocity is function of cavitation and of injector model (MPI-1, MPI-2, effective)...

Andrea March 7, 2008 21:30

Re: how to give pressure as an input in spray mode
 
Excuse me,
for the question about the spray angle: use the Huh's atomization model (you'll choose injection with atomizatio I suppose...). With that you don't need to specify any spray angle because it is determined internally by the model (refer to the metodology for details)
Regards

Andrea March 7, 2008 21:33

Re: how to give pressure as an input in spray mode
 
...third thing: you can define an injection with an injection velocity independent of the mass flow rate...I don't know it it is useful for you but if it is I can tell you how to setup that sim...
Bye!


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