Investigation of pressure and the Lewis number effects in the context of algebraic flame surface density closure for LES
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O R I G I NA L A RT I C L E
Usman Allauddin Michael Pfitzner
· Sai Ranjith Reddy Lomada ·
Investigation of pressure and the Lewis number effects in the context of algebraic flame surface density closure for LES of premixed turbulent combustion Received: 2 November 2019 / Accepted: 25 June 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Large scale industrial combustion devices, for example, internal combustion engines, gas turbine combustors, etc., operate under high-pressure conditions and utilize a variety of fuels. Unfortunately, the majority of the current numerical combustion modelling approaches are not fully validated for high-pressure and the non-unity Lewis number (Le = thermal diffusivity/mass diffusivity) effects in premixed turbulent combustion. In any case, a numerical model needs to be checked for the effects of these parameters to guarantee generality of the model. In the present study, these two critical features of the models are numerically explored utilizing fundamental elements of several algebraic flame surface density reaction rate closure models accessible in the open literature. The Lewis number impact is likewise examined utilizing LES of recently published subgrid scale fractal flame surface density model, which indicated acceptable results for high and low-pressure methane fuelled applications. The computed numerical results are compared with an extensive experimental dataset for lean methane and propane fuels featuring various flow and turbulence conditions at operating pressures in the range of 1–10 bar. The quantitative results from most of the selected models do not show the experimentally observed trends at high-pressures and for non-unity Le number fuels. Modifications to the models are incorporated to reflect effects of these two important parameters utilizing a broad parametric investigation resulting in a satisfactory agreement with the experimental data. Keywords Large Eddy simulation · Turbulent premixed combustion · Flame surface density · High-pressure flames · Lewis number
List of symbols c CA CD CK CZ D Da
Reaction progress variable Angelberger model constant Keppeler model constant Keppeler model constant Zimont model constant Fractal dimension Damköhler number
Communicated by Patrick Jenny. U. Allauddin · S. R. R. Lomada · M. Pfitzner Institut für Thermodynamik, Fakultät für Luft-und Raumfahrttechnik, Universität der Bundeswehr München, 85579 Neubiberg, Germany U. Allauddin (B) Department of Mechanical Engineering, NED University of Engineering and Technology, Karachi 75270, Pakistan E-mail: [email protected]
U. Allauddin et al.
k Ka l Le Ma p Re sT sL0 sL Si j Sct t T u u ui U xi
Turbulent kinetic energy (m2 /s2 ) Subgrid Karlovitz number Integral length scale of turbulence (m) Lewis number Markstein number Pressure, Pa Reynolds number Turbulent flame speed (m/s) Un-stretched laminar flame speed (m/s) Stretched laminar flame speed (m/s) Shear stress tensor (1/s) Schmidt number Time (s) Temperature (K) RMS turbulent
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