[hamedc]

Hi,

I've entered the shape values from the laboratory injector data that was tested with the Bosch test.
I've imported this values by scaling only the positive values of ROI(g/s) with the desired duration(ms), into the shape rate profile.
I also have considered a dwell time between two injection timing.
In contrast to the main injector pressure, more pressure is obtained (or Cd) using spray calculator.
My main question is how to obtain the shape values from the ROI(g/s) data?

Thank you in advance
Regards,

[tmburton]

Hamed,

The rate shape you enter in CONVERGE Studio during spray setup is just a way of prescribing the shape of the mass flow rate vs. time profile for your injection event. CONVERGE will shift the x-axis (time or CA) to begin at inject_start_time, scale the x-axis (time or CA) to fit into your specified inject_duration, and scale the y-axis (mass flow rate or velocity) to achieve the required inject_mass.

Best regards,

Tristan

[hamedc]

Originally Posted by tmburton

Hamed,

The rate shape you enter in CONVERGE Studio during spray setup is just a way of prescribing the shape of the mass flow rate vs. time profile for your injection event. CONVERGE will shift the x-axis (time or CA) to begin at inject_start_time, scale the x-axis (time or CA) to fit into your specified inject_duration, and scale the y-axis (mass flow rate or velocity) to achieve the required inject_mass.

Best regards,

Tristan

Thank you for your reply.

I have an injector that injects the iso-octane in two stages and at a pressure of 1000 bar.
I used a trapezoidal profile as rate shape and set the axis. however, the spray calculator determined over-predicted value for injection pressure.

I have attached these rate values.

Best regards,
Hamed

[tmburton]

Hamed,

Is your engine speed 1250 RPM? When I plug this into the spray rate calculator with your rate shape, I get peak pressures around 890 bar.

Best regards,

Tristan

[hamedc]

Originally Posted by tmburton

Hamed,

Is your engine speed 1250 RPM? When I plug this into the spray rate calculator with your rate shape, I get peak pressures around 890 bar.

Best regards,

Tristan

My engine speed is 1300 RPM.
Are the rate values I entered wrong?

Best regards,
Hamed

[tmburton]

Hamed,

I plugged your rate shape into our PFI example case and used the spray rate calculator as a quick check (see attached). Our example case has 4 nozzles each of 250 micron diameter. Your injector may be different.

Best regards,

Tristan

[hamedc]

Originally Posted by tmburton

Hamed,

I plugged your rate shape into our PFI example case and used the spray rate calculator as a quick check (see attached). Our example case has 4 nozzles each of 250 micron diameter. Your injector may be different.

Best regards,

Tristan

My injector has 7 nozzles each of 141 micron diameter
Thank you for your response

Best regards,
Hamed

[tmburton]

Hamed,

Under those conditions, I see peak pressures of 2085 bar for C_D=0.8, and 1334 bar for C_D=1.0. If these values are too high then you should check your injection duration, injected mass, and nozzle diameter values.

Best regards,

Tristan