燃燒仿真軟件OpenFOAM教程：燃燒模型與化學(xué)反應(yīng)機(jī)理

燃燒仿真軟件OpenFOAM教程：燃燒模型與化學(xué)反應(yīng)機(jī)理1燃燒仿真基礎(chǔ)1.1燃燒的基本概念燃燒是一種化學(xué)反應(yīng)過(guò)程，其中燃料與氧化劑（通常是空氣中的氧氣）反應(yīng)，產(chǎn)生熱能和光能，以及一系列的化學(xué)產(chǎn)物。燃燒過(guò)程可以分為三個(gè)主要階段：預(yù)熱階段、燃燒階段和后燃階段。預(yù)熱階段燃料被加熱至其著火點(diǎn)；燃燒階段燃料與氧化劑反應(yīng)，釋放大量能量；后燃階段，反應(yīng)產(chǎn)物繼續(xù)冷卻并最終達(dá)到環(huán)境溫度。燃燒的特性可以通過(guò)幾個(gè)關(guān)鍵參數(shù)來(lái)描述，包括燃燒速度、火焰溫度、燃燒效率等。燃燒速度是指燃料與氧化劑反應(yīng)的速率，它受到燃料類型、溫度、壓力和反應(yīng)物濃度的影響?；鹧鏈囟仁侨紵^(guò)程中產(chǎn)生的最高溫度，通常與燃燒效率和產(chǎn)物的組成有關(guān)。燃燒效率衡量了燃料中化學(xué)能轉(zhuǎn)化為熱能的比例。1.2燃燒模型的分類燃燒模型用于描述和預(yù)測(cè)燃燒過(guò)程中的物理和化學(xué)行為。根據(jù)其復(fù)雜性和應(yīng)用范圍，燃燒模型可以分為以下幾類：零維模型：假設(shè)燃燒在無(wú)限小的體積內(nèi)進(jìn)行，忽略空間變化，僅考慮時(shí)間變化。適用于描述燃燒室內(nèi)的整體燃燒過(guò)程。一維模型：考慮燃燒過(guò)程在單一方向上的變化，如火焰?zhèn)鞑?。適用于描述層流火焰的特性。二維和三維模型：考慮燃燒過(guò)程在兩個(gè)或三個(gè)方向上的變化，能夠更準(zhǔn)確地模擬實(shí)際燃燒環(huán)境中的復(fù)雜流動(dòng)和傳熱現(xiàn)象。適用于描述湍流燃燒和多相燃燒。在OpenFOAM中，常用的燃燒模型包括：層流燃燒模型：假設(shè)燃燒過(guò)程在層流條件下進(jìn)行，適用于低速燃燒和預(yù)混燃燒。湍流燃燒模型：考慮湍流對(duì)燃燒過(guò)程的影響，適用于高速燃燒和非預(yù)混燃燒。多相燃燒模型：考慮燃燒過(guò)程中不同相態(tài)（如氣相、液相、固相）之間的相互作用，適用于描述噴霧燃燒和固體燃料燃燒。1.3化學(xué)反應(yīng)機(jī)理簡(jiǎn)介化學(xué)反應(yīng)機(jī)理描述了化學(xué)反應(yīng)的詳細(xì)步驟，包括反應(yīng)物之間的相互作用、中間產(chǎn)物的形成以及最終產(chǎn)物的生成。在燃燒仿真中，化學(xué)反應(yīng)機(jī)理是模擬燃燒過(guò)程的關(guān)鍵，它決定了燃燒的速率、產(chǎn)物的組成以及能量的釋放。OpenFOAM支持多種化學(xué)反應(yīng)機(jī)理，包括：簡(jiǎn)單反應(yīng)機(jī)理：如一步反應(yīng)模型，適用于快速燃燒過(guò)程的簡(jiǎn)化模擬。詳細(xì)反應(yīng)機(jī)理：如GRI-Mech3.0，包含數(shù)百個(gè)反應(yīng)步驟，能夠更準(zhǔn)確地描述復(fù)雜燃料的燃燒過(guò)程。1.3.1示例：使用OpenFOAM進(jìn)行層流燃燒仿真以下是一個(gè)使用OpenFOAM進(jìn)行層流燃燒仿真的簡(jiǎn)單示例。我們將使用層流燃燒模型和一個(gè)簡(jiǎn)化的一步反應(yīng)機(jī)理來(lái)模擬甲烷在空氣中的燃燒。1.3.1.1準(zhǔn)備仿真環(huán)境首先，確保OpenFOAM已經(jīng)安裝在你的系統(tǒng)上。然后，創(chuàng)建一個(gè)新的案例目錄，并在其中設(shè)置物理屬性和初始條件。#創(chuàng)建案例目錄

mkdirmethaneAirCombustion

cdmethaneAirCombustion

#初始化案例

foamDictionary-cloneconstant/thermophysicalProperties1.3.1.2設(shè)置化學(xué)反應(yīng)機(jī)理在constant目錄下創(chuàng)建一個(gè)chemistryProperties文件，用于定義化學(xué)反應(yīng)機(jī)理。這里我們使用一個(gè)簡(jiǎn)化的一步反應(yīng)機(jī)理：echo"

typeoneStep;

chemistryTypefiniteRate;

">constant/chemistryProperties1.3.1.3定義燃料和氧化劑的物理屬性在constant/thermophysicalProperties文件中，定義甲烷和空氣的物理屬性：thermoType

{

typehePsiThermo;

mixturemixture;

transportconst;

thermohConst;

equationOfStateperfectGas;

speciespecie;

energysensibleInternalEnergy;

}

mixture

{

specie

{

species(CH4O2N2H2OCO2);

equationOfState

{

speciespecie;

energysensibleInternalEnergy;

}

}

thermodynamics

{

CH4

{

molWeight16.04;

CpCoeffs(1.664E+031.17E-02-2.195E-061.432E-09-9.817E-14);

Hf-5.092E+04;

}

O2

{

molWeight32.00;

CpCoeffs(1.035E+030.0);

Hf0.0;

}

N2

{

molWeight28.01;

CpCoeffs(1.042E+030.0);

Hf0.0;

}

H2O

{

molWeight18.015;

CpCoeffs(1.333E+030.0);

Hf-2.418E+05;

}

CO2

{

molWeight44.01;

CpCoeffs(1.333E+030.0);

Hf-3.935E+05;

}

}

transport

{

CH4

{

As4.265E-20;

Cs1.0;

Pr0.72;

}

O2

{

As2.66E-19;

Cs1.0;

Pr0.72;

}

N2

{

As2.66E-19;

Cs1.0;

Pr0.72;

}

H2O

{

As6.419E-20;

Cs1.0;

Pr0.72;

}

CO2

{

As5.474E-20;

Cs1.0;

Pr0.72;

}

}

}1.3.1.4設(shè)置初始和邊界條件在0目錄下，設(shè)置初始和邊界條件。這里我們假設(shè)一個(gè)簡(jiǎn)單的二維燃燒室，其中甲烷從左側(cè)進(jìn)入，空氣從右側(cè)進(jìn)入：#設(shè)置速度場(chǎng)

echo"

(

(000)

(000)

)

">0/U

#設(shè)置壓力場(chǎng)

echo"

(

101325

101325

)

">0/p

#設(shè)置溫度場(chǎng)

echo"

(

300

300

)

">0/T

#設(shè)置化學(xué)組分場(chǎng)

echo"

(

(10000)

(00.210.7900)

)

">0/Y1.3.1.5運(yùn)行仿真使用OpenFOAM的層流燃燒求解器laminarFoam來(lái)運(yùn)行仿真：laminarFoam1.3.1.6分析結(jié)果仿真完成后，可以使用OpenFOAM自帶的后處理工具，如paraFoam，來(lái)可視化和分析仿真結(jié)果：paraFoam在paraFoam中，可以查看溫度分布、化學(xué)組分濃度、燃燒速度等關(guān)鍵參數(shù)，以評(píng)估燃燒過(guò)程的特性。通過(guò)以上步驟，我們展示了如何使用OpenFOAM進(jìn)行層流燃燒仿真的基本流程。這僅為燃燒仿真的一小部分，實(shí)際應(yīng)用中可能需要更復(fù)雜的模型和更詳細(xì)的化學(xué)反應(yīng)機(jī)理來(lái)準(zhǔn)確預(yù)測(cè)燃燒過(guò)程。2OpenFOAM入門2.1OpenFOAM概述OpenFOAM（OpenFieldOperationandManipulation）是一個(gè)開(kāi)源的CFD（計(jì)算流體動(dòng)力學(xué)）軟件包，由OpenCFD有限公司開(kāi)發(fā)并維護(hù)，現(xiàn)由SINTEFDigital的FoamFoundation管理。它提供了一系列的工具和求解器，用于模擬復(fù)雜的流體流動(dòng)、傳熱、燃燒等現(xiàn)象。OpenFOAM的核心優(yōu)勢(shì)在于其高度的靈活性和可擴(kuò)展性，允許用戶自定義模型和方程，以適應(yīng)特定的研究或工程需求。2.2OpenFOAM的安裝與配置2.2.1安裝步驟下載OpenFOAM安裝包：訪問(wèn)OpenFOAM官方網(wǎng)站，下載適合你操作系統(tǒng)的安裝包。安裝依賴庫(kù)：在Ubuntu系統(tǒng)中，可以使用以下命令安裝所需的依賴庫(kù)：sudoapt-getupdate

sudoapt-getinstallbuild-essentialcmakelibopenmpi-devopenmpi-binlibblas-devliblapack-devlibfftw3-devlibboost-all-dev解壓并編譯OpenFOAM：解壓下載的安裝包，并進(jìn)入解壓后的目錄，運(yùn)行./Allwmake進(jìn)行編譯。配置環(huán)境變量：編輯.bashrc文件，添加以下行：exportWM_PROJECT_DIR=<OpenFOAM安裝目錄>

source$WM_PROJECT_DIR/etc/bashrc測(cè)試安裝：運(yùn)行test-all命令，確保所有測(cè)試通過(guò)。2.2.2配置步驟設(shè)置求解器路徑：在.bashrc中，確保$WM_PROJECT_DIR指向正確的OpenFOAM安裝目錄。更新環(huán)境變量：運(yùn)行source~/.bashrc，使更改的環(huán)境變量生效。安裝額外庫(kù)：根據(jù)需要，安裝額外的庫(kù)或模塊，如化學(xué)反應(yīng)庫(kù)chemkin。2.3OpenFOAM案例運(yùn)行流程2.3.1創(chuàng)建案例目錄OpenFOAM使用案例目錄來(lái)組織和運(yùn)行模擬。每個(gè)案例目錄包含所有必要的輸入文件，如網(wǎng)格、邊界條件、物理屬性和控制參數(shù)。創(chuàng)建案例目錄的基本步驟如下：復(fù)制模板案例：使用foamCloneCase命令從OpenFOAM的$FOAM_TUTORIALS目錄中復(fù)制一個(gè)模板案例。foamCloneCase$FOAM_TUTORIALS/<應(yīng)用>/<案例名>2.3.2編輯輸入文件案例目錄中的輸入文件需要根據(jù)模擬需求進(jìn)行編輯。主要的輸入文件包括：系統(tǒng)文件：如controlDict（控制模擬的參數(shù)）、fvSchemes（離散方案）、fvSolution（求解策略）。邊界條件文件：如0目錄下的U（速度）、p（壓力）、T（溫度）等。物理屬性文件：如constant目錄下的transportProperties（傳輸屬性）、thermophysicalProperties（熱物理屬性）。2.3.3運(yùn)行求解器編輯完輸入文件后，使用相應(yīng)的求解器運(yùn)行模擬。例如，對(duì)于穩(wěn)態(tài)燃燒模擬，可以使用simpleFoam求解器。simpleFoam2.3.4后處理和可視化模擬完成后，使用paraFoam或foamToVTK將結(jié)果轉(zhuǎn)換為ParaView或VTK格式，以便于可視化和分析。foamToVTKtime=<時(shí)間步>2.3.5示例：簡(jiǎn)單燃燒模擬假設(shè)我們想要模擬一個(gè)簡(jiǎn)單的燃燒過(guò)程，可以使用chemReactFoam求解器。下面是一個(gè)簡(jiǎn)化的案例目錄結(jié)構(gòu)和輸入文件示例：2.3.5.1案例目錄結(jié)構(gòu)<案例目錄>

|--0

||--U

||--p

||--T

||--Y

|--constant

||--polyMesh

||--transportProperties

||--thermophysicalProperties

||--chemistryProperties

|--system

||--controlDict

||--fvSchemes

||--fvSolution2.3.5.2controlDict示例startFromstartTime;

startTime0;

stopAtendTime;

endTime10;

deltaT0.01;

writeControltimeStep;

writeInterval1;

purgeWrite0;

writeFormatascii;

writePrecision6;

writeCompressionoff;

timeFormatrunTime;

timePrecision6;2.3.5.3thermophysicalProperties示例thermoType

{

typehePsiThermo;

mixturespecies;

transportconst;

thermohConst;

equationOfStateperfectGas;

speciespecie;

energysensibleInternalEnergy;

}

mixture

{

specie

{

species(O2N2CO2COH2O);

}

thermodynamics

{

path$FOAM_THERMOS/75Components;

file75ComponentsH2O_CO2_N2_O2_CO_Pr.dat;

}

}2.3.5.4運(yùn)行求解器chemReactFoam2.3.5.5后處理和可視化foamToVTKtime=10以上步驟和示例提供了OpenFOAM入門的基本流程和操作，通過(guò)這些步驟，用戶可以開(kāi)始探索和使用OpenFOAM進(jìn)行復(fù)雜的燃燒仿真。3OpenFOAM中的燃燒模型3.1非預(yù)混燃燒模型3.1.1原理非預(yù)混燃燒模型（Non-premixedcombustionmodel）適用于燃料和氧化劑在燃燒前未充分混合的場(chǎng)景，如柴油發(fā)動(dòng)機(jī)中的燃燒過(guò)程。在非預(yù)混燃燒中，燃燒速率由燃料和氧化劑的擴(kuò)散速率決定，因此，模型需要解決燃料和氧化劑的擴(kuò)散以及反應(yīng)速率問(wèn)題。OpenFOAM中的非預(yù)混燃燒模型通常基于EddyDissipationModel(EDM)或者EddyDissipationConcept(EDC)。3.1.2內(nèi)容在OpenFOAM中，非預(yù)混燃燒模型通過(guò)解決湍流擴(kuò)散和化學(xué)反應(yīng)速率來(lái)模擬燃燒過(guò)程。模型中需要定義燃料和氧化劑的物理和化學(xué)性質(zhì)，包括擴(kuò)散系數(shù)、反應(yīng)速率常數(shù)等。此外，還需要定義湍流模型，如k-ε模型或k-ω模型，以計(jì)算湍流對(duì)燃燒的影響。3.1.2.1示例代碼#在OpenFOAM中設(shè)置非預(yù)混燃燒模型的示例

#配置文件：constant/turbulenceProperties

simulationTypeRAS;

RAS

{

RASModelkEpsilon;

turbulenceon;

printCoeffson;

}#配置文件：constant/thermophysicalProperties

thermodynamics

{

thermoType

{

typehePsiThermo;

mixturemixture;

transportconst;

thermohConst;

equationOfStateidealGas;

speciespecie;

energysensibleInternalEnergy;

}

mixture

{

typereactingMixture;

transportModelconst;

thermoModelhConst;

equationOfStateidealGas;

specieModelspecie;

energyModelsensibleInternalEnergy;

mixtureairFuel;

}

}#配置文件：constant/reactingMixtureProperties

thermodynamics

{

...

}

transport

{

...

}

species

{

nSpecies2;

species(airfuel);

}

equationOfState

{

...

}

thermo

{

...

}

transportModel

{

...

}

reactionModel

{

typefiniteRate;

chemistryReaderCHEMKIN;

chemistry(chem.inpspeciesData);

}3.1.3解釋上述代碼示例展示了如何在OpenFOAM中配置非預(yù)混燃燒模型。首先，在constant/turbulenceProperties文件中，我們定義了湍流模型為k-ε模型。然后，在constant/thermophysicalProperties文件中，我們定義了熱物理屬性，包括使用hePsiThermo類型和reactingMixture混合物類型。最后，在constant/reactingMixtureProperties文件中，我們定義了反應(yīng)模型為finiteRate類型，使用CHEMKIN格式讀取化學(xué)反應(yīng)機(jī)理文件。3.2預(yù)混燃燒模型3.2.1原理預(yù)混燃燒模型（Premixedcombustionmodel）適用于燃料和氧化劑在燃燒前已經(jīng)充分混合的場(chǎng)景，如天然氣燃燒。預(yù)混燃燒模型通常基于火焰?zhèn)鞑ダ碚?，考慮火焰鋒面的傳播速度和化學(xué)反應(yīng)速率。3.2.2內(nèi)容在OpenFOAM中，預(yù)混燃燒模型通過(guò)解決火焰鋒面的傳播速度和化學(xué)反應(yīng)速率來(lái)模擬燃燒過(guò)程。模型中需要定義燃料和氧化劑的物理和化學(xué)性質(zhì)，包括火焰?zhèn)鞑ニ俣?、化學(xué)反應(yīng)速率等。此外，還需要定義湍流模型，以計(jì)算湍流對(duì)火焰鋒面的影響。3.2.2.1示例代碼#在OpenFOAM中設(shè)置預(yù)混燃燒模型的示例

#配置文件：constant/thermophysicalProperties

thermodynamics

{

thermoType

{

typehePsiThermo;

mixturemixture;

transportconst;

thermohConst;

equationOfStateidealGas;

speciespecie;

energysensibleInternalEnergy;

}

mixture

{

typereactingMixture;

transportModelconst;

thermoModelhConst;

equationOfStateidealGas;

specieModelspecie;

energyModelsensibleInternalEnergy;

mixturepremixed;

}

}#配置文件：constant/reactingMixtureProperties

thermodynamics

{

...

}

transport

{

...

}

species

{

nSpecies2;

species(airfuel);

}

equationOfState

{

...

}

thermo

{

...

}

transportModel

{

...

}

reactionModel

{

typelaminar;

chemistryReaderCHEMKIN;

chemistry(chem.inpspeciesData);

}3.2.3解釋上述代碼示例展示了如何在OpenFOAM中配置預(yù)混燃燒模型。在constant/thermophysicalProperties文件中，我們定義了熱物理屬性，包括使用hePsiThermo類型和reactingMixture混合物類型，特別指出混合物類型為premixed。在constant/reactingMixtureProperties文件中，我們定義了反應(yīng)模型為laminar類型，使用CHEMKIN格式讀取化學(xué)反應(yīng)機(jī)理文件。3.3詳細(xì)化學(xué)反應(yīng)機(jī)理模型3.3.1原理詳細(xì)化學(xué)反應(yīng)機(jī)理模型（Detailedchemicalkineticsmodel）考慮了化學(xué)反應(yīng)的每一個(gè)步驟，包括中間產(chǎn)物和副反應(yīng)。這種模型能夠提供更準(zhǔn)確的燃燒過(guò)程描述，但計(jì)算成本較高。3.3.2內(nèi)容在OpenFOAM中，詳細(xì)化學(xué)反應(yīng)機(jī)理模型通過(guò)解決復(fù)雜的化學(xué)反應(yīng)網(wǎng)絡(luò)來(lái)模擬燃燒過(guò)程。模型中需要定義燃料和氧化劑的物理和化學(xué)性質(zhì)，包括詳細(xì)的化學(xué)反應(yīng)機(jī)理文件。此外，還需要定義反應(yīng)速率常數(shù)、活化能等參數(shù)。3.3.2.1示例代碼#在OpenFOAM中設(shè)置詳細(xì)化學(xué)反應(yīng)機(jī)理模型的示例

#配置文件：constant/reactingMixtureProperties

reactionModel

{

typefiniteRate;

chemistryReaderCHEMKIN;

chemistry(chem.inpspeciesData);

}#化學(xué)反應(yīng)機(jī)理文件：chem.inp

ELEMENTS

CHON

SPECIES

CO2COH2H2OHO2N2NO

EQUATIONS

H2+0.5O2=H2O

CO+0.5O2=CO2

...3.3.3解釋在constant/reactingMixtureProperties文件中，我們定義了反應(yīng)模型為finiteRate類型，使用CHEMKIN格式讀取化學(xué)反應(yīng)機(jī)理文件?；瘜W(xué)反應(yīng)機(jī)理文件chem.inp中定義了參與反應(yīng)的元素、物種以及化學(xué)反應(yīng)方程式。這種模型能夠更精確地模擬燃燒過(guò)程，但需要更復(fù)雜的化學(xué)反應(yīng)機(jī)理文件和更高的計(jì)算資源。通過(guò)以上示例，我們可以看到在OpenFOAM中如何配置非預(yù)混燃燒模型、預(yù)混燃燒模型以及詳細(xì)化學(xué)反應(yīng)機(jī)理模型。每種模型都有其適用場(chǎng)景和配置方法，選擇合適的模型對(duì)于準(zhǔn)確模擬燃燒過(guò)程至關(guān)重要。4化學(xué)反應(yīng)機(jī)理在OpenFOAM中的應(yīng)用4.1化學(xué)反應(yīng)機(jī)理文件格式在OpenFOAM中，化學(xué)反應(yīng)機(jī)理通常以擴(kuò)展名為.cti的文件格式存儲(chǔ)，這是Chemkin格式的文件。Chemkin是一個(gè)廣泛使用的化學(xué)動(dòng)力學(xué)軟件包，用于描述和模擬化學(xué)反應(yīng)。OpenFOAM通過(guò)讀取Chemkin格式的文件來(lái)解析化學(xué)反應(yīng)機(jī)理，包括反應(yīng)物、產(chǎn)物、反應(yīng)速率常數(shù)等信息。4.1.1示例：Chemkin格式的化學(xué)反應(yīng)機(jī)理文件#以下是一個(gè)簡(jiǎn)單的Chemkin格式的化學(xué)反應(yīng)機(jī)理文件示例

#物種定義

SPECIES

O2,O,O2+,O+,O2-,O-,O2(4S),O(3P),O(1D)

END

#反應(yīng)定義

REACTIONS

UNITSMOLESYES

O2+M=O2(4S)+M1.000E+000.000E+00-1.170E+04

O2(4S)+M=O2+M2.000E+000.000E+000.000E+00

END

#熱力學(xué)數(shù)據(jù)

THERMALL

O2(4S)25.0000001000.0000006000.000000

1.000000E+000.000000E+000.000000E+000.000000E+00

0.000000E+000.000000E+000.000000E+000.000000E+00

0.000000E+000.000000E+000.000000E+000.000000E+00

0.000000E+000.000000E+000.000000E+000.000000E+00

0.000000E+000.000000E+000.000000E+000.000000E+00

0.000000E+000.000000E+000.000000E+000.000000E+00

0.000000E+000.000000E+000.000000E+000.000000E+00

0.000000E+000.000000E+000.000000E+000.000000E+00

0.000000E+000.000000E+000.000000E+000.000000E+00

END在這個(gè)示例中，我們定義了幾個(gè)物種（O2,O,O2+,等）和兩個(gè)反應(yīng)。每個(gè)反應(yīng)都有其特定的速率常數(shù)，這些常數(shù)在不同溫度下可能有所不同。熱力學(xué)數(shù)據(jù)部分提供了物種的熱力學(xué)屬性，這對(duì)于計(jì)算反應(yīng)速率和平衡狀態(tài)至關(guān)重要。4.2導(dǎo)入化學(xué)反應(yīng)機(jī)理要將化學(xué)反應(yīng)機(jī)理導(dǎo)入OpenFOAM，需要將.cti文件轉(zhuǎn)換為OpenFOAM可讀的格式。OpenFOAM提供了chemkinToOpenFOAM工具來(lái)完成這一轉(zhuǎn)換。4.2.1示例：使用chemkinToOpenFOAM導(dǎo)入化學(xué)反應(yīng)機(jī)理chemkinToOpenFOAM-chemkinFilepath/to/your/chemkinFile.cti-speciesFilepath/to/your/speciesFile.txt-thermoFilepath/to/your/thermoFile.dat在這個(gè)命令中，-chemkinFile參數(shù)指定了Chemkin格式的化學(xué)反應(yīng)機(jī)理文件路徑，-speciesFile參數(shù)指定了物種定義文件路徑，而-thermoFile參數(shù)指定了熱力學(xué)數(shù)據(jù)文件路徑。執(zhí)行此命令后，OpenFOAM將生成一系列文件，包括物種屬性、反應(yīng)速率和熱力學(xué)數(shù)據(jù)，這些文件將被存儲(chǔ)在constant目錄下的thermophysicalProperties文件中。4.3設(shè)置燃燒模型參數(shù)在OpenFOAM中，燃燒模型參數(shù)是在constant目錄下的thermophysicalProperties文件中設(shè)置的。這個(gè)文件包含了流體的物理和化學(xué)屬性，以及燃燒模型的詳細(xì)配置。4.3.1示例：thermophysicalProperties文件配置thermodynamics

{

thermoType

{

typehePsiThermo;

mixtureperfectGas;

transportconst;

thermoHSD;

equationOfStateyes;

speciespecie;

energysensibleInternalEnergy;

}

}

transport

{

transportModelconst;

}

species

{

nSpecies3;

speciesList(O2OO2(4S));

}

equationOfState

{

p0101325;

T0300;

}

thermodynamics

{

Tinf298.15;

}

reactionModel

{

typefiniteRate;

chemistryReaderchemistry;

chemistrychemistry.cti;

chemistryFormatchemkin;

chemistryTypegas;

chemistrySolverimplicit;

chemistryTol1e-6;

chemistryRes1e-3;

chemistryMaxIter100;

}在這個(gè)示例中，我們定義了熱力學(xué)模型、運(yùn)輸模型、物種列表、反應(yīng)模型等參數(shù)。reactionModel部分特別重要，它指定了反應(yīng)模型的類型（finiteRate表示有限速率模型），以及化學(xué)反應(yīng)機(jī)理文件的路徑（chemistry.cti）。此外，還設(shè)置了化學(xué)反應(yīng)求解器的參數(shù)，如容差（chemistryTol）、殘差（chemistryRes）和最大迭代次數(shù)（chemistryMaxIter）。通過(guò)以上步驟，我們可以將復(fù)雜的化學(xué)反應(yīng)機(jī)理集成到OpenFOAM中，從而進(jìn)行詳細(xì)的燃燒仿真。這不僅包括了化學(xué)反應(yīng)的動(dòng)態(tài)模擬，還涵蓋了熱力學(xué)和運(yùn)輸屬性的計(jì)算，為燃燒過(guò)程的全面理解提供了強(qiáng)大的工具。5OpenFOAM燃燒仿真案例分析5.1非預(yù)混燃燒案例設(shè)置5.1.1原理與內(nèi)容非預(yù)混燃燒（DiffusionBurning）是指燃料和氧化劑在燃燒前未充分混合，燃燒過(guò)程主要發(fā)生在燃料和氧化劑的界面處。在OpenFOAM中，模擬非預(yù)混燃燒通常采用reactingMultiphaseFoam或laminarReactingMultiphaseFoam等求解器，這些求解器能夠處理多相流和化學(xué)反應(yīng)。5.1.1.1案例設(shè)置步驟定義物理模型：選擇適當(dāng)?shù)奈锢砟Ｐ?，如湍流模型（k-epsilon或k-omega）和燃燒模型（如EDC或PDF）。網(wǎng)格劃分：使用blockMesh或snappyHexMesh生成網(wǎng)格。邊界條件：設(shè)置燃料和氧化劑的入口邊界條件，以及出口和壁面條件。初始化條件：設(shè)置初始溫度、壓力、組分濃度等?；瘜W(xué)反應(yīng)機(jī)理：選擇合適的化學(xué)反應(yīng)機(jī)理，如GRI-Mech3.0。運(yùn)行仿真：使用求解器進(jìn)行仿真，監(jiān)控收斂情況。5.1.1.2代碼示例在constant/thermophysicalProperties文件中定義化學(xué)反應(yīng)機(jī)理：thermodynamics

{

thermoType

{

typehePsiThermo;

mixturemixture;

transportconst;

thermohConst;

equationOfStateperfectGas;

speciespecie;

energysensibleInternalEnergy;

}

mixture

{

typereactingMixture;

transportModellaminar;

thermoTypehConst;

equationOfStateperfectGas;

speciespecie;

energysensibleInternalEnergy;

mixtureGRI30;

}

}

transport

{

transportModellaminar;

}

reaction

{

reactionModelconstant;

chemistryReader

{

typeCHEMKIN;

mechanismFile"GRI-Mech301.cti";

speciesFile"speciesDict";

thermodynamicsFile"GRI-Mech301.Therm";

}

}在0目錄下初始化溫度和組分：T

{

typevolScalarField;

Time0;

classthermophysical;

location"0";

objectT;

dimensions[0001000];

internalFielduniform300;

boundaryField

{

fuelInlet

{

typefixedValue;

valueuniform300;

}

oxidizerInlet

{

typefixedValue;

valueuniform300;

}

outlet

{

typezeroGradient;

}

walls

{

typefixedValue;

valueuniform300;

}

}

}

Y

{

typevolScalarField;

Time0;

classthermophysical;

location"0";

objectY;

dimensions[0000100];

internalFieldnonuniformList<scalar>

(

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0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,

0.0,0.0,0.0,

#高