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EFFECTS OF RADIATIVE HEAT TRANSFER ON THE TURBULENCE STRUCTURE IN REACTING AND INERT MIXING LAYERS

Somnath Ghosh
Lehrstuhl für Aerodynamik, Technische Universität München Boltzmannstrasse 15, D-85748 Garching, Germany; Department of Aerospace Engineering, Indian Institute of Technology, Kharagpur, India

Rainer Friedrich
Lehrstuhl für Aerodynamik, Technische Universität München Boltzmannstrasse 15, D-85748 Garching, Germany

Christian Stemmer
Lehrstuhl fur Aerodynamik, Technische Universitat Munchen Boltzmannstr. 15, D-85748 Garching, Germany

Benedicte Cuenot
Cerfacs

Mouna El Hafi
Centre Energetique-Environnement CNRS - Faculté des Sciences et Techniques; Laboratoire de Géenie des Procédés des Solides Divisés, Ecole des Mines d'Albi, Carmaux, France

Resumo

We use large-eddy simulation to study the interaction between turbulence and radiative heat transfer in low-speed inert and reacting plane temporal mixing layers. An explicit filtering scheme based on approximate deconvolution is applied to treat the closure problem arising from quadratic nonlinearities of the filtered transport equations. In the reacting case, the working fluid is a mixture of ideal gases where the low-speed stream consists of hydrogen and nitrogen and the high-speed stream of oxygen and nitrogen. Both streams are premixed in a way that the free-stream densities are the same and the stoichiometric mixture fraction is 0.3. The filtered heat release term is modelled using equilibrium chemistry. In the inert case the low-speed stream consists of nitrogen at a temperature of 1000 K and the high-speed stream is pure water vapour of 2000 K, when the radiation is turned off. Simulations assuming the gas mixtures as grey gases with artificially increased Planck mean absorption coefficients are performed in which the LES code and the radiation code PRISSMA are fully coupled. In both cases radiative heat transfer is found to clearly affect fluctuations of thermodynamic variables, Reynolds stresses and budget terms like pressure-strain correlations. Source terms in the transport equation for the variance of temperature fluctuations are used to explain the decrease of this variance in the reacting case and its increase in the inert case.