[mturcios777]

I'm trying to get the same behaviour of the commonRailInjector with the new lagrangian classes (almost repeated the thread title verbatim), and using it under something like sprayFoam. I was curious if the following section in the Properties file had anything to do with injection pressure:

constantProperties
{
     parcelTypeId    1;

     rhoMin          1e-15;
     TMin            200;
     pMin            1000;
     minParticleMass 1e-15;

     rho0            1000;
     T0              320;
     Cp0             4187;

     youngsModulus   1e9;
     poissonsRatio   0.35;

     epsilon0        1;
     f0              0.5;
     Pr              0.7;
     Tvap            273;
     Tbp             373;

    constantVolume  false;
}

Do these properties have anything to do with conditions at the injector? If not I'm having trouble seeing how to specify such conditions. Are there plans to implement that type of functionality in the library, or perhaps a utility to convert a combination of the old sprayProperties+injectorProperties = sprayCloudProperties? Either case sounds like the same amount of work...

[mturcios777]

Though I would still like to know the answer to this question, it appears that you can specify the flowType as:

flowRateAndDischarge <-- The default one from the tutorials
constantVelocity
pressureDrivenVelocity <-- The one I will try and use

So that would be enough for me for now, though specifying injection temperature as well would be nice too.

[arash1]

Hello Marco,

It seems to me that the parameters rho0, Tvap, Tbp, and Cp0 in constantProperties should not be specified by user because all these data are already included for different liquids in /src/thermophysicalModels/properties. In fact, the initial properties can be calculated by using special formulas (e.g. see H2OI.H) whose inputs are just T0 and (gas) pressure at the injection point.

So, I don't understand why the developer(s) should have written the code in the way that requires the mentioned initial injection properties, and risking the inconsistency between date inputed by user and date that are hardcoded.

Any idea?

[u22]

Hello Marco. Have you been succeed with converting old properties of common rail injector to new spraycloud properties?

[wadekar]

Originally Posted by mturcios777

Though I would still like to know the answer to this question, it appears that you can specify the flowType as:

flowRateAndDischarge <-- The default one from the tutorials
constantVelocity
pressureDrivenVelocity <-- The one I will try and use

So that would be enough for me for now, though specifying injection temperature as well would be nice too.

what's the actual difference between this flowTypes ??

i wonder which one should i use, either flowRateAndDischarge or pressureDrivenVelocity ?

Thanks in advance

[einstein_zee]

Originally Posted by wadekar

what's the actual difference between this flowTypes ??

i wonder which one should i use, either flowRateAndDischarge or pressureDrivenVelocity ?

Thanks in advance

Hey there,

the difference is in how he really calculates U. In flowRateAndDischarge it uses U = V_dot/(A*Cd) and in pressureDrivenVelocity it uses U = sqrt(2*(Pinj - Pamb)/rho).

hope this helps...

[wadekar]

Originally Posted by einstein_zee

Hey there,

the difference is in how he really calculates U. In flowRateAndDischarge it uses U = V_dot/(A*Cd) and in pressureDrivenVelocity it uses U = sqrt(2*(Pinj - Pamb)/rho).

hope this helps...

Thanks for reply!

that means
1. if i use pressureDrivenVelocity then i don't need to have flow rate profile (I have it from measurements).
2. whats the impact of this two different flowType on liquid penetration length ?

I did the simulation with both flowTypes and rest the settings are completely same.
results: The penetration with flowRateAndDischarge is very short as compared to pressureDrivenVelocity....

So i confused which one is correct.


Thanks in advance!

[JensenZHAI]

if I change the FlowType to be pressureDrivenVelocity, which part should be modified in sprayCloudProperties?

May I have a look at your sprayCloudProperties?