A Numerical Investigation of Mixing Models in LES-FMDF for Compressible Reactive Flows
The filtered mass density function (FMDF) model has been employed for large-eddy simulations (LES) of compressible high-speed turbulent mixing and reacting flows. However, the mixing model remains a pressing challenge for FMDF methods, especially for compressible reactive flows. In this work, a temp...
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doaj-e07e6637a9aa4681a81cdba3fcd35d712021-08-26T13:43:43ZengMDPI AGEnergies1996-10732021-08-01145180518010.3390/en14165180A Numerical Investigation of Mixing Models in LES-FMDF for Compressible Reactive FlowsWenwu Chen0Jianhan Liang1Lin Zhang2Qingdi Guan3College of Aerospace Science and Engineering, National University of Defense Technology, No.109 Deya Road, Changsha 410073, ChinaCollege of Aerospace Science and Engineering, National University of Defense Technology, No.109 Deya Road, Changsha 410073, ChinaCollege of Aerospace Science and Engineering, National University of Defense Technology, No.109 Deya Road, Changsha 410073, ChinaCollege of Aerospace Science and Engineering, National University of Defense Technology, No.109 Deya Road, Changsha 410073, ChinaThe filtered mass density function (FMDF) model has been employed for large-eddy simulations (LES) of compressible high-speed turbulent mixing and reacting flows. However, the mixing model remains a pressing challenge for FMDF methods, especially for compressible reactive flows. In this work, a temporal development mixing layer with two different convective Mach numbers, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi mathvariant="normal">M</mi><mi mathvariant="normal">c</mi></msub><mrow><mo>=</mo><mn>0.4</mn></mrow></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi mathvariant="normal">M</mi><mi mathvariant="normal">c</mi></msub><mrow><mo>=</mo><mn>0.8</mn></mrow></mrow></semantics></math></inline-formula>, is used to investigate the mixing models. A simplified one-step reaction and a real hydrogen/air reaction are employed to study the mixing and turbulence-chemistry interaction. Two widely used mixing models, interaction by exchange with the mean (IEM) and Euclidean minimum spanning tree (EMST), are studied. Numerical results indicate that no difference is observed between the IEM and EMST models in simple reaction flows. However, for hydrogen/air reactions, the EMST model can predict the reaction more accurately in high-speed flow. For mixing models in compressible reactive flows, the requirement of localness preservation tends to be more essential as the convective Mach number increases. With the increase of compressibility, the sensitivity of the mixing model coefficient is reduced significantly. Therefore, the appropriate mixing model coefficient has a wider range. Results also indicate that a large error may result when using a fixed mixing model coefficient in compressible flows.https://www.mdpi.com/1996-1073/14/16/5180LES-FMDFmixing modelscompressible reactive flows |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Wenwu Chen Jianhan Liang Lin Zhang Qingdi Guan |
spellingShingle |
Wenwu Chen Jianhan Liang Lin Zhang Qingdi Guan A Numerical Investigation of Mixing Models in LES-FMDF for Compressible Reactive Flows Energies LES-FMDF mixing models compressible reactive flows |
author_facet |
Wenwu Chen Jianhan Liang Lin Zhang Qingdi Guan |
author_sort |
Wenwu Chen |
title |
A Numerical Investigation of Mixing Models in LES-FMDF for Compressible Reactive Flows |
title_short |
A Numerical Investigation of Mixing Models in LES-FMDF for Compressible Reactive Flows |
title_full |
A Numerical Investigation of Mixing Models in LES-FMDF for Compressible Reactive Flows |
title_fullStr |
A Numerical Investigation of Mixing Models in LES-FMDF for Compressible Reactive Flows |
title_full_unstemmed |
A Numerical Investigation of Mixing Models in LES-FMDF for Compressible Reactive Flows |
title_sort |
numerical investigation of mixing models in les-fmdf for compressible reactive flows |
publisher |
MDPI AG |
series |
Energies |
issn |
1996-1073 |
publishDate |
2021-08-01 |
description |
The filtered mass density function (FMDF) model has been employed for large-eddy simulations (LES) of compressible high-speed turbulent mixing and reacting flows. However, the mixing model remains a pressing challenge for FMDF methods, especially for compressible reactive flows. In this work, a temporal development mixing layer with two different convective Mach numbers, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi mathvariant="normal">M</mi><mi mathvariant="normal">c</mi></msub><mrow><mo>=</mo><mn>0.4</mn></mrow></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi mathvariant="normal">M</mi><mi mathvariant="normal">c</mi></msub><mrow><mo>=</mo><mn>0.8</mn></mrow></mrow></semantics></math></inline-formula>, is used to investigate the mixing models. A simplified one-step reaction and a real hydrogen/air reaction are employed to study the mixing and turbulence-chemistry interaction. Two widely used mixing models, interaction by exchange with the mean (IEM) and Euclidean minimum spanning tree (EMST), are studied. Numerical results indicate that no difference is observed between the IEM and EMST models in simple reaction flows. However, for hydrogen/air reactions, the EMST model can predict the reaction more accurately in high-speed flow. For mixing models in compressible reactive flows, the requirement of localness preservation tends to be more essential as the convective Mach number increases. With the increase of compressibility, the sensitivity of the mixing model coefficient is reduced significantly. Therefore, the appropriate mixing model coefficient has a wider range. Results also indicate that a large error may result when using a fixed mixing model coefficient in compressible flows. |
topic |
LES-FMDF mixing models compressible reactive flows |
url |
https://www.mdpi.com/1996-1073/14/16/5180 |
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