Title: Assumed PDF modelling and PDF structure investigation using finite-rate chemistry

Authors: Peter Gerlinger, Berthold Noll, Manfred Aigner

Addresses: Institute of Aerospace Combustion Technology, University of Stuttgart, Pfaffenwaldring 38-40, Stuttgart 70569, Germany. ' Institute of Combustion Technology, DLR Stuttgart, Pfaffenwaldring 38-40, Stuttgart 70569, Germany. ' Institute of Combustion Technology, DLR Stuttgart, Pfaffenwaldring 38-40, Stuttgart 70569, Germany

Abstract: An assumed probability density function (PDF) approach is used for the simulation of turbulent high speed combustion with finite-rate chemistry. The PDFs employed are a clipped Gaussian distribution for temperature and a joint multi-variate β-distribution for an arbitrary number of species mass fractions. The definition of both PDFs is based on higher order moments obtained from additional transport equations. In the present work, a transport equation for the variance of temperature and the sum of species mass fraction variances is solved. The numerical approach is compared with experimental data of a Mach 2 supersonic hydrogen-air diffusion flame. The focus of this paper is on the investigation of the marginal PDFs of temperature and species molar fractions at representative spatial positions. Moreover, two-dimensional marginal PDFs of pairs of species mass fractions are compared with experimental results. It is shown that the assumed PDF approach achieves a good agreement with experimental data concerning first and second moments and that even the shape of the PDF is met relatively well.

Keywords: assumed PDF modelling; turbulent diffusion flame; combustion modelling; supersonic flow; probability density function; PDF structure; finite-rate chemistry; simulation.

DOI: 10.1504/PCFD.2005.007066

Progress in Computational Fluid Dynamics, An International Journal, 2005 Vol.5 No.6, pp.334 - 344

Available online: 17 May 2005 *

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