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modelling of si engine

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  • December 23, 2014 at 4:16 am #337
    Leonktz LeonktzLeonktz Leonktz
    Member

    Hi,
    I am modelling a si engine.
    I used a MEP motor. And gave relative fuel-air ratio of 0.0714(1/14).
    1) can i give the same fuel-air ratio in the ducts?
    2) what mass of air and fuel should i enter in wiebe’s combustion model?
    3) inspite of changing all these parameters, i am getting the same air-fuel ratio(4.63) at the output.
    Is there any example model of si engine that i can refer?

    December 23, 2014 at 4:15 pm #503
    sreenathiit12sreenathiit12
    Member

    Traditionally spark ignition engines work with a relative fuel to air ratio of 1 (near the stoichiometric).
    I don’t understand the second question.
    Related with the wiebe, you must provide the operating conditions (fuel mass, air mass and engine speed) of the engine for each wiebe. If you give only one wiebe these parameters won’t be used. In case that you give more than than 2 wiebes the model will interpolate between them taking account the operating conditions of the wiebes and the operating conditions of the point that is being simulated.

    December 23, 2014 at 4:42 pm #504
    Leonktz LeonktzLeonktz Leonktz
    Member

    In the engine block, we are asked to give input for relative fuel-air ratio.
    let relative air-fuel ratio be 14
    When I simulate, the calculated air fuel ratio comes out to be 4.36…Why is it so??

    Also how to calculate the mass of fuel intake per cycle?

    February 10, 2016 at 4:55 pm #715
    Mateusz GandykMateusz Gandyk
    Participant

    Have you finally done SI engine?

    Is here anyone who have done SI engine and want to shear?

    I wanted to do that, but when I am changing motor type to spark ignited it is loosing all the power.

    When I additionaly want to run that model with single wiebe equation solver crashes.

    I received such an information: “The model is not validated for gasoline engines, then the code can contain bugs for this type of simulations. The only way to detect and correct the issue is to debug the code.”

    Maybe someone solved that problem or is able to solve.

    I attached my engine model conversion.

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    June 28, 2017 at 10:24 am #781
    Emil GuptaGupta
    Participant

    I am also trying to model SI engines from given CI engine models. Could anyone help me out?What are the parameters i have to consider while converting CI engine model to  SI engine models.Please help me out..

    June 28, 2017 at 11:14 am #782
    F. J. ArnauArnau F. J.
    Keymaster

    I’m not sure if the model is ready to simulate SI engines. You cannot inject fuel outside the chamber. Probably you need some tricks to model this type of engine.

    June 28, 2017 at 12:15 pm #783
    Emil GuptaGupta
    Participant

    what could be the possible trick?

    June 28, 2017 at 12:16 pm #784
    Emil GuptaGupta
    Participant

    and also which element will do the function of spark plug in si engine?

     

    June 28, 2017 at 12:29 pm #785
    Emil GuptaGupta
    Participant

    Could you please suggest me some papers or any reference documents related to this. It would be very helpful.

     

    June 28, 2017 at 2:22 pm #786
    F. J. ArnauArnau F. J.
    Keymaster

    I don’t know paper related with this. We never have modelled SI engines with openwam. But you use a wiebe function for combustión and inject in the chamber the corresponding fuel to get relative fuel to air ratio similar to one like SI engines. The main difference is the combustion process, the rest of elements are similar.

    July 5, 2017 at 9:16 am #787
    Emil GuptaGupta
    Participant

    Hey!!

    I have not found the information related to firing order.

    How can i know the order of firing  ?

    Thank you in advance

     

    July 14, 2017 at 8:13 am #792
    Emil GuptaGupta
    Participant

    My Question is that “ How can i enter these different valve lift in simulation model ?“

    I have 4 valves (2 inlet valves and 2 outlet valves) for each cylinder in Gasoline Engine:

    2 Inlet valves have
    • 7 mm lift for first inlet valve
    • 10,5 mm lift for second inlet valve

    2 outlet valves have
    • 9 mm lift for first outlet valve
    • 10 mm lift for second outlet valve

    September 1, 2017 at 9:53 am #800
    Emil GuptaGupta
    Participant

    In pressure vs Crank angle graph of my simulation result:

    ” Pressure drops from 12 bar to 1 bar directly (within 1 degree crank angle duration) in exhaust side of the graph ”

    Can any one knows the reason for that problem?

    Thank you in advance

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