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April 6, 2020, 13:16 |
How to slow down the parcels?
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#1 |
Senior Member
LT
Join Date: Dec 2010
Posts: 104
Rep Power: 16 |
Hi, everyone, I am simulating a high injection pressure spray at different ambient pressures with sprayFoam solver. The case is running smoothly, but some predicted results do not agree with the experimental data very well. Therefore, I list some questions here and look for the possible answers or clues.
Questions #1: the parcels goes too fast after they come out of the nozzle exit, i.e. the penetration increases too fast. I have set the pressure at "uniform 2.0e6", the density is about 20kg/m^3, the predicted spray reaches the bottom of the domain (0.08m) at 0.001s while the experimental spray penetration is only 0.065m at 0.002s. Question #2: if the parameter "parcelBasisType" in sprayCloudProperties is mass, how to config "flowRateProfile table"? Then what's the unit of "flowRateProfile table"? Question #3: when the simulated fuel is decane(nC10H22), will OpenFoam give the properties itself or look for them in the therm.dat, if "defaultCoeffs" is yes? Thanks in advance! |
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April 6, 2020, 13:19 |
thermophysicalProperties file
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#2 |
Senior Member
LT
Join Date: Dec 2010
Posts: 104
Rep Power: 16 |
FoamFile
{ version 2.0; format binary; class dictionary; location "constant"; object SprayCloudProperties; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // solution { active true; coupled true; transient yes; cellValueSourceCorrection on; maxCo 0.3; sourceTerms { schemes { rho explicit 1; U explicit 1; Yi explicit 1; h explicit 1; radiation explicit 1; } } interpolationSchemes { rho cell; U cellPoint; thermo:mu cell; T cell; Cp cell; kappa cell; p cell; } integrationSchemes { U Euler; T analytical; } } constantProperties { T0 300; // place holders for rho0 and Cp0 // - reset from liquid properties using T0 rho0 798.13;//1000; Cp0 4187; constantVolume false; } subModels { particleForces { sphereDrag; } injectionModels { model1 { type coneNozzleInjection; SOI 0; massTotal 2.38e-5;//5.85e-6;//6.0e-6; parcelBasisType mass; injectionMethod disc; flowType pressureDrivenVelocity;//flowRateAndDischarge; Pinj 70e+6; outerDiameter 0.15e-3;//1.9e-4; innerDiameter 0; duration 2e-3; position (0 0 0);//(0 0.0995 0); direction (0 0 -1); parcelsPerSecond 40000000; flowRateProfile table//unit is m^3/s ( (0 1.49e-5)//(0 1) (0.002 1.49e-5)//(0.002 1) ); Cd constant 0.9; thetaInner constant 0.0; thetaOuter constant 18.0;//10.0; sizeDistribution { type RosinRammler; RosinRammlerDistribution { minValue 1e-06; maxValue 0.00013; d 0.00013; n 3; } } } } dispersionModel none;//stochasticDispersionRAS;//gradientDispersionRAS;//none; patchInteractionModel standardWallInteraction; heatTransferModel RanzMarshall; compositionModel singlePhaseMixture; phaseChangeModel liquidEvaporationBoil; surfaceFilmModel none; atomizationModel blobsSheetAtomization;//none; breakupModel ReitzKHRT; // ReitzDiwakar; stochasticCollisionModel trajectory;//none; radiation off; standardWallInteractionCoeffs { type rebound; } RanzMarshallCoeffs { BirdCorrection true; } singlePhaseMixtureCoeffs { phases ( liquid { C10H22 1; } ); } liquidEvaporationBoilCoeffs { enthalpyTransfer enthalpyDifference; activeLiquids ( C10H22 ); } ReitzDiwakarCoeffs { solveOscillationEq yes; Cbag 6; Cb 0.785; Cstrip 0.5; Cs 10; } ReitzKHRTCoeffs { solveOscillationEq yes; B0 0.61; B1 40; Ctau 1; CRT 0.1; msLimit 0.2; WeberLimit 6; } TABCoeffs { y0 0; yDot0 0; Cmu 10; Comega 8; WeCrit 12; } trajectoryCoeffs { cSpace 1; cTime 0.3; coalescence on; } blobsSheetAtomizationCoeffs { B 1.0; angle 30.0; } } cloudFunctions {} // ************************************************** *********************** // |
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April 6, 2020, 13:20 |
p in 0 fold
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#3 |
Senior Member
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Join Date: Dec 2010
Posts: 104
Rep Power: 16 |
FoamFile
{ version 2.0; format ascii; class volScalarField; object p; } // ************************************************** *********************** // dimensions [1 -1 -2 0 0 0 0]; internalField uniform 2e+06; boundaryField { Outlet { type zeroGradient; } Walls { type zeroGradient; } Inlet { type zeroGradient; } } // ************************************************** *********************** // |
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April 6, 2020, 13:25 |
Another point
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#4 |
Senior Member
LT
Join Date: Dec 2010
Posts: 104
Rep Power: 16 |
Another point is the parameters "massTotal" and "parcelsPerSecond", do they make the predicted penetration longer if I increase the former and decrease the latter? And how do they affect the computation?
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Tags |
parcels, penetration, sprayfoam |
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