A Generic Gas Radiative Property Model Applicable to CFD Simulations of all Combustion Processes
Author
Sanchez Romero, Sergio
Term
4. term
Education
Publication year
2016
Submitted on
2016-05-24
Pages
130
Abstract
This thesis presents the development and testing of a generic gas radiative property model for CFD simulations of combustion. The model is a computationally efficient Exponential Wide Band Model (E-EWBM) implemented in C++ to calculate emissivity of gas mixtures. The code is validated and embedded in Fluent to evaluate its applicability under both air-fuel and oxy-fuel conditions. The study contrasts the proposed approach with established radiative property models and also examines the influence of different global reaction mechanisms and mesh sensitivity. Across 12 simulations, the E-EWBM notably alters the predicted absorption coefficient, while its impact on temperature, axial velocity, and major species fields is small; by contrast, the choice of reaction mechanism strongly affects combustion and flow outcomes. A 3D mesh is also constructed for an oxy-fuel furnace, where the model again yields pronounced differences in the absorption coefficient. The results indicate that an efficient, generic spectral model can be coupled to industrial CFD tools, that radiative property selection chiefly affects radiation-related quantities, and that combustion chemistry has greater leverage on thermofluid predictions; avenues for future work are outlined.
Denne afhandling beskriver udviklingen og afprøvningen af en generisk model for gasers strålingsegenskaber til CFD-simuleringer af forbrænding. Modellen bygger på en beregningsmæssigt effektiv Exponential Wide Band Model (E-EWBM) skrevet i C++ til beregning af emissivitet i gasblandinger. Koden er valideret og indlejret i Fluent for at vurdere dens anvendelighed under både luft-brændsel- og oxy-fuel-betingelser. Arbejdet sammenligner den foreslåede model med etablerede radiative egenskabsmodeller og undersøger også betydningen af forskellige globale reaktionsmekanismer samt maskefølsomhed. På tværs af 12 simuleringer påvirker E-EWBM især den forudsagte absorptionskoefficient, mens indflydelsen på temperatur, aksial hastighed og nøglearter er begrænset; omvendt har valget af reaktionsmekanisme en markant effekt på forbrændings- og strømningsegenskaberne. Der er desuden opbygget et 3D-gitter til en oxy-fuel-ovn, hvor modellen igen giver tydelige forskelle i absorptionskoefficienten. Resultaterne viser, at en effektiv, generisk spektralmodel kan kobles til industrielle CFD-værktøjer, at radiative egenskabsvalg primært påvirker strålingsrelaterede størrelser, og at kemimekanismer i højere grad styrer termofluidiske forudsigelser; rapporten skitserer også perspektiver for fremtidigt arbejde.
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