Accession Number:

ADA411692

Title:

PDF Modelling of Turbulent Combustion

Descriptive Note:

Final technical rept. 15 Feb 2000-30 Sep 2002

Corporate Author:

CORNELL UNIV ITHACA NY DEPT OF MECHANICAL AND AEROSPACE ENGINEERING

Personal Author(s):

Report Date:

2002-09-01

Pagination or Media Count:

59.0

Abstract:

Significant advances have been made in several aspects of the computational modelling of turbulent combustion. PDF model calculations have been performed of turbulent piloted-jet non-premixed flames. The results demonstrated the ability of the methodology to account, accurately, for the local extinction and reignition observed experimentally in these flames. It was shown that these flames can be sensitive to the temperature of the pilot and to radiative heat loss. A new approach has been developed for the efficient computational implementation of combustion chemistry. The rate controlled constrained equilibrium method has been combined with the in Situ adaptive tabulation algorithm to produce a unified dimension-reductionstorage-retrieval methodology for the computationally-efficient implementation of combustion chemistry. Test calculations demonstrated that this methodology has comparable accuracy to augmented reduced mechanisms. Ideas from the conditional moment closure and the mapping closure have been combined to produce a new approach for modeling molecular mixing in turbulent reactive flows. The new methodology has been shown to describe accurately for the first time the mixing of two scalars. A methodology has been developed for obtaining stochastic models for Lagrangian velocity and acceleration based on DNS data from homogeneous turbulent shear flow. It has been shown that the acceleration model provides a remarkably accurate representation of the observed Lagrangian velocity-acceleration two-time correlations. In collaboration with the group of Prof. P. Givi, advances have been made in the implementation of a combined LESPDF methodology for modeling turbulent reactive flows. The approach based on the velocity filtered density function has been applied to a spatially developing mixing layer and shown to account well for the major processes in this flow.

Subject Categories:

  • Physical Chemistry
  • Numerical Mathematics
  • Combustion and Ignition

Distribution Statement:

APPROVED FOR PUBLIC RELEASE