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Old   October 2, 2017, 15:46
Default injection pressure
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amin u3fi
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Hello,

I know there is no injection pressure input when simulating diesel engine combustion. So, I entered the mass (3e-6) and injection duration (6 deg) based on experimental data. CONVERGE gave me the injection pressure of 70 bar. However, in experiments, the injection pressure of common rail system is 520 bar. So, I was wondering why converge underpredicts the injection pressure?
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Old   October 2, 2017, 17:21
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Amin,

What is your engine speed? I guessed 1800 rpm and used 3e-05 kg of IC8H18 in 6 CAD and got an injection pressure of 593 bar from CONVERGE Studio's Spray rate calculator. Are you certain your injected mass is 3 mg and not 30 mg?

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Old   October 2, 2017, 17:26
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Quote:
Originally Posted by tmburton View Post
Amin,

What is your engine speed? I guessed 1800 rpm and used 3e-05 kg of IC8H18 in 6 CAD and got an injection pressure of 593 bar from CONVERGE Studio's Spray rate calculator. Are you certain your injected mass is 3 mg and not 30 mg?

Best regards,

Tristan
Hello,

I'm simulating dual-fuel engine and it's 1/6 of the combustion chamber. The total amount of diesel is 18 mg/cycle c7h16 and for 1/6 sector should be 3 mg/cycle. The engine rpm is 910 and injection duration is 6 deg.
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Old   October 2, 2017, 17:50
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Amin,

What is your injector nozzle diameter?

Best regards,

Tristan
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Old   October 2, 2017, 17:56
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Quote:
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Amin,

What is your injector nozzle diameter?

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Tristan
It's 0.00023 m. I put this data in spray rate calculator and it gives me 86 bar.
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Old   October 2, 2017, 18:06
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Amin,

What value are you using for the nozzle discharge coefficient and how are you specifying the velocity coefficient?

Best regards,

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Old   October 2, 2017, 18:12
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Quote:
Originally Posted by tmburton View Post
Amin,

What value are you using for the nozzle discharge coefficient and how are you specifying the velocity coefficient?

Best regards,

Tristan
We don't have data for the discharge coefficient. However, it is mostly between 0.6-0.8. I've used 0.7.
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Old   October 2, 2017, 18:22
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Amin,

Ok, I get something similar to your value. However, it seems unlikely that the pressure just upstream of the nozzle holes (what CONVERGE reports) is 520 bar for this combination of parameters.

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Old   October 11, 2017, 07:14
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Hi Trisan,

Can you please suggest, where can i get CONVERGE Studio's Spray rate calculator.

Thanks in advance.

Best regards,
Krishna
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Old   October 11, 2017, 12:21
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Krishna,

It's under the Spray modeling -> Injectors -> Tools button in Studio.

Best regards,

Tristan
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File Type: jpg SprayRateCalculator.jpg (109.3 KB, 13 views)
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Old   October 12, 2017, 09:35
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Thank you Trisan.
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Old   November 6, 2017, 03:43
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My engien speed is 1500 rmp/s but the injector is not like that. Maybe there is something wrong on othe parts
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