injection pressure

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 October 2, 2017, 15:46 injection pressure #1 Senior Member   amin u3fi Join Date: Feb 2013 Posts: 134 Rep Power: 7 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?

 October 2, 2017, 17:21 #2 Member     Tristan Burton Join Date: Sep 2017 Posts: 79 Rep Power: 3 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 __________________ Tristan Burton Senior Principal Engineer CONVERGECFD

October 2, 2017, 17:26
#3
Senior Member

amin u3fi
Join Date: Feb 2013
Posts: 134
Rep Power: 7
Quote:
 Originally Posted by tmburton 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.

 October 2, 2017, 17:50 #4 Member     Tristan Burton Join Date: Sep 2017 Posts: 79 Rep Power: 3 Amin, What is your injector nozzle diameter? Best regards, Tristan __________________ Tristan Burton Senior Principal Engineer CONVERGECFD

October 2, 2017, 17:56
#5
Senior Member

amin u3fi
Join Date: Feb 2013
Posts: 134
Rep Power: 7
Quote:
 Originally Posted by tmburton Amin, What is your injector nozzle diameter? Best regards, Tristan
It's 0.00023 m. I put this data in spray rate calculator and it gives me 86 bar.

 October 2, 2017, 18:06 #6 Member     Tristan Burton Join Date: Sep 2017 Posts: 79 Rep Power: 3 Amin, What value are you using for the nozzle discharge coefficient and how are you specifying the velocity coefficient? Best regards, Tristan __________________ Tristan Burton Senior Principal Engineer CONVERGECFD

October 2, 2017, 18:12
#7
Senior Member

amin u3fi
Join Date: Feb 2013
Posts: 134
Rep Power: 7
Quote:
 Originally Posted by tmburton 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.

 October 2, 2017, 18:22 #8 Member     Tristan Burton Join Date: Sep 2017 Posts: 79 Rep Power: 3 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. Best regards, Tristan __________________ Tristan Burton Senior Principal Engineer CONVERGECFD

 October 11, 2017, 07:14 #9 Member   Krishna Join Date: Apr 2012 Posts: 52 Rep Power: 8 Hi Trisan, Can you please suggest, where can i get CONVERGE Studio's Spray rate calculator. Thanks in advance. Best regards, Krishna

October 11, 2017, 12:21
#10
Member

Tristan Burton
Join Date: Sep 2017
Posts: 79
Rep Power: 3
Krishna,

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

Best regards,

Tristan
Attached Images
 SprayRateCalculator.jpg (109.3 KB, 16 views)
__________________
Tristan Burton
Senior Principal Engineer
CONVERGECFD

 October 12, 2017, 09:35 #11 Member   Krishna Join Date: Apr 2012 Posts: 52 Rep Power: 8 Thank you Trisan.

 November 6, 2017, 02:43 #12 New Member   shelleyvander Join Date: Nov 2017 Posts: 4 Rep Power: 2 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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