[s.chen8]

Hi all,



I wonder if anyone can share some information about this questions.

Recently I used Converge for some spray-modeling and in-cylinder DI simulation. The embedded spray calculator which offers fast calculation on max-pressure, discharge coefficient(Cd) and injection duration, is very helpful.

However, some quesitons were raised while applying this calculator, in which the simulation is closed to real-case or not.

for the same injector,
Q1 - While changing injection-mass and thus injection duration(based on supplier function report), under same max pressure(i.e 350 bar), does it need to update the Cd value?

Q2 - While changing max-pressure(i.e 350bar to 200bar), changing injection-duration for the same fuel amount, does it need to update the Cd value?

Q3 - Does the Cd value stick to injection pressure? or injector design? or fuel injection region(non-linear region and linear region)?

Q4 - Does the max-pressure mean fuel_rail pressure? or is it related to pressure drop crossing injector chamber and nozzle-zone?


You are more than welcome to share some paper-info or other experience. Thank you very much!

[awaikar]

Hello shanghua, thank you for your question.
For Q1 and Q2: you can check what input parameters have been used in the calculator, if CD is the input parameter, you will need to provide that/or not use CD model. If CD is instead an output parameter, then you would not need to worry about it as the calculator will output a value.

Q3: you should either directly provide a value, or the solver will calculate it based on the options for velocity coefficient CV.

Q4:you need to self-estimate the pressure drop between the rail and the injector, the formulations of calculating the pressure are in the Studio manual.

Let us know if you have any more questions.
Regards,