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hi my friends,
what should i do to reach high compression ratio in kivaTest? what's the role of the clearance and conRodLength ?
thanks in advance

----

hi nishio,
you can change stoichiometricAirFuelMassRatio stoichiometricAirFuelMassRatio [ 0 0 0 0 0 0 0 ] 15.0336; to any value that you want

hi ,
I want to run the blow case in kivaTest,
Engine Specifications
Engine
Bore=81 mm
Stroke=88 mm
Displaced Volume=453.46 cm 3
Clearance Volume=27.82 cm 3
Compression Ratio=17.3 : 1
but I receive Vmax = 0.000631297, Vmin = 4.65038e-05
Vmax/Vmin = 13.5752:(:confused:

and when I want to run i receive from log ,
Mean pressure:6.29685e+59 :confused:
Mean temperature:2847.02
Mean u':203.613
ExecutionTime = 125.73 s ClockTime = 126 s

Courant Number mean: 5.68007e+36 max: 1.72382e+40
Crank angle = -20.75 CA-deg
deltaZ = 8.60734e-05
clearance: 0.00125427
Piston speed = 3.30522 m/s
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
PIMPLE: iteration 1
DILUPBiCG: Solving for Ux, Initial residual = 0.15084, Final residual = 6.32512e-06, No Iterations 3
DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 1.529e-06, No Iterations 3
DILUPBiCG: Solving for Uz, Initial residual = 0.998471, Final residual = 3.86051e-06, No Iterations 3
DILUPBiCG: Solving for ft, Initial residual = 0.998068, Final residual = 2.16875e-06, No Iterations 2
PLEASE help me.

Quick answers:

Quote:

Originally Posted by kaveh19 (Post 559125)

what's the role of the clearance and conRodLength ?

Quoting from the source code: https://raw.githubusercontent.com/Op...e/engineTime.H

Code:

            //- Return the engines connecting-rod length

            const dimensionedScalar& conRodLength() const

            {

                return conRodLength_;

            }



            //- Return the engines bore

            const dimensionedScalar& bore() const

            {

                return bore_;

            }



            //- Return the engines stroke

            const dimensionedScalar& stroke() const

            {

                return stroke_;

            }



            //- Return the engines clearance-gap

            const dimensionedScalar& clearance() const

            {

                return clearance_;

            }

Units: https://raw.githubusercontent.com/Op...e/engineTime.C

Code:

    conRodLength_(dimensionedScalar("conRodLength", dimLength, 0)),

    bore_(dimensionedScalar("bore", dimLength, 0)),

    stroke_(dimensionedScalar("stroke", dimLength, 0)),

    clearance_(dimensionedScalar("clearance", dimLength, 0))

Namely, all are in metre (meter).

--------------

Quote:

Originally Posted by kaveh19 (Post 559989)

Questions:

What are the settings you used in "constant/engineGeometry"?
Did you change the mesh or are you using the same one from the tutorial?
If you changed the mesh, in what units was the original mesh generated in, because you might have converted incorrect the dimensions of the mesh, for example you might have in millimetre and have to convert to metre.

----
edit: duplicate question had been asked... will address the topic to here: http://www.cfd-online.com/Forums/ope...tml#post560504

hi wyldckat,
1)Bore=0.081 ,Stroke=0.088
2)no i didn't

Quote:

Originally Posted by kaveh19 (Post 560707)

1)Bore=0.081 ,Stroke=0.088

That didn't answer my question. But it doesn't matter, because your questions on this topic are being answered in this thread: http://www.cfd-online.com/Forums/ope...ilitities.html - and on that thread you provided more details, some of which answered my previous questions.

hi my friend,

Would you please send the 5-steps ch4/air mechanism to me? my email address:13903423r@connect.polyu.hk. Thank you so much!

Sean

Hi all,

I'm completely new on combustion, so I would like to apologize first for my lake of knowledge, and the stupidity I will probably write.

FIRST:
I was wondering if one of you has the documents posted by Mr. Weller at the very beginning of that topic. (Because of the age of this topic the links aren't still available sadly...).

SECOND:
Without any disrespect (on the contrary, I admire the work that has been done), because of the age of this model, is there nowadays any new model (usable in RANS simulation) that are now more efficient to model the turbulent flame speed than the Weller one ?

FIRD:
This question is more personal. In fact I'm a student in internship, and my tutor want me to simulate explosion on large scale simulation (on tunnel about 10 meters) (in order to compare the result to the FLACS code one). Do you think that XiFoam would be appropriate for that type of simulation ?

Thank you,
Adrien.