Accelerating the Computation of Chemical Reaction Kinetics for Modeling Turbulent Reacting Flows PDF Download

Author: Sudip Adhikari
Publisher:
ISBN:
Category : Combustion
Languages : en
Pages : 111

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Book Description
Modeling of pollutants such as soot and other byproduct formation inside the practical combustion devices have become an increasingly important research topic over the past couple of decades. However, the accurate prediction of emission requires robust and efficient computational methods for modeling of turbulent reacting flows. One of the most computationally efficient modeling approaches is a combination of a Reynolds-averaged Navier Stokes (RANS) approach and eddy dissipation concept (EDC), where the former addresses the flow turbulence, while the latter accounts for the turbulence-chemistry interactions. EDC includes a fine structure of turbulence known as perfectly stirred reactors (PSRs). A PSR model based on the hybrid Newton/time integration methodology is developed and coupled to two state-of-the-art soot moment techniques, namely the method of moments with interpolative closure (MOMIC) and the hybrid method of moments (HMOM), with the latter coupling being implemented for the first time, for investigating soot formation and growth.The PSR algorithm employs a procedure of switching between steady-state and pseudo-transient calculations of the nonlinear algebraic steady PSR equations in order to achieve a more conditioned estimate of the initial guess. Soot moment equations are coupled with species conservation equations to obtain soot quantities such as soot volume fraction, particle number density, particle diameter and soot surface area density. The PSR algorithm based on hybrid Newton/time integration approach is extended and implemented in the context of two-dimensional (2D) eddy dissipation concept (EDC) simulations of turbulent flames. Furthermore, an efficient computational implementation of in situ adaptive tabulation (ISAT) approach for combustion chemistry in a network of perfectly stirred reactors (PSRs) is also presented, and the developed implementation is extended in two different contexts; for the EDC calculations of 2D turbulent flames, and for the acceleration of computation of soot formation and growth in a network of perfectly stirred reactors (PSRs). A step by step procedure is developed for the calculation of reaction mapping gradient matrix needed for ISAT calculations in the context of PSRs. A series of PSR calculations is carried out using the direct integration (DI) and ISAT approaches. Validation of DI is performed through comparisons with previous experiments. In addition, results from different test cases are presented and the speedup of ISAT over Direct Integration (DI) is also calculated. Finally, a highly parallelized GPU implementation is presented for a batched calculation of PSR model, using a robust and efficient non-linear solver for gas phase chemical reactions and is further coupled to one of the widely used moment methods of solutions of soot equations, the Method of Moment with Interpolative Closure (MOMIC).