Computational study of turbulent unconfined swirl flames

This study investigates the performance of Reynolds Averaged Navier-Stokes technique in predicting the behavior of swirl flames as well as a parametric study on the effects of fuel jet velocity and swirl number on the structure of the swirl flames. Two turbulence models which are realizable k-e and...

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Main Author:	Mohd. Azli, Anis Athirah
Format:	Thesis
Language:	English
Published:	2015
Subjects:	TJ Mechanical engineering and machinery
Online Access:	http://eprints.utm.my/id/eprint/53519/1/AnisAthirahMohdAzliMFKM2015.pdf
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spelling	my-utm-ep.535192020-07-16T07:55:00Z Computational study of turbulent unconfined swirl flames 2015-06 Mohd. Azli, Anis Athirah TJ Mechanical engineering and machinery This study investigates the performance of Reynolds Averaged Navier-Stokes technique in predicting the behavior of swirl flames as well as a parametric study on the effects of fuel jet velocity and swirl number on the structure of the swirl flames. Two turbulence models which are realizable k-e and standard k-? from RANS technique were chosen and applied as the closure model. Comparison of simulation results were done with the experimental evidence obtained from Sydney University database and it is found that both models show good performance in predicting the turbulent swirl flame near the vicinity of the burner exit plane. However, due to isotropic nature of the two-eddy viscosity model, turbulent swirl flows farther downstream were not accurately captured. Parametric studies on the effects of fuel jet velocity and swirl number on the swirl flame structure were done. Simulation of turbulent unconfined swirl flames shows that the structure of the swirl flames is consists of outer and inner recirculation zones. The outer recirculation zone occurs due to the bluff-body effect; meanwhile the inner recirculation zone occurs farther downstream due to reversed flow. For fuel jet velocity, an increase in the velocity causes suspension of the occurrence of secondary recirculation zone. In this case, for higher fuel jet velocity, longer time is required for the fuel jet to decay and recirculation zone to form. In addition to that, the flame height increases with increasing fuel jet velocity. On the other hand, an increase in swirl number causes an increase in flame width and flame height. Results from the simulation have also shown that for low swirl number of 0.3, recirculation zones were absent. As swirl number increases, the tangential momentum of air flow increase and therefore greater adverse pressure gradient will be produced. As a result, fuel jet is prohibited to travel farther downstream, and flow is reversed back into the recirculation zone. 2015-06 Thesis http://eprints.utm.my/id/eprint/53519/ http://eprints.utm.my/id/eprint/53519/1/AnisAthirahMohdAzliMFKM2015.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:84898 masters Universiti Teknologi Malaysia, Faculty of Mechanical Engineering Faculty of Mechanical Engineering
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	TJ Mechanical engineering and machinery
spellingShingle	TJ Mechanical engineering and machinery Mohd. Azli, Anis Athirah Computational study of turbulent unconfined swirl flames
description	This study investigates the performance of Reynolds Averaged Navier-Stokes technique in predicting the behavior of swirl flames as well as a parametric study on the effects of fuel jet velocity and swirl number on the structure of the swirl flames. Two turbulence models which are realizable k-e and standard k-? from RANS technique were chosen and applied as the closure model. Comparison of simulation results were done with the experimental evidence obtained from Sydney University database and it is found that both models show good performance in predicting the turbulent swirl flame near the vicinity of the burner exit plane. However, due to isotropic nature of the two-eddy viscosity model, turbulent swirl flows farther downstream were not accurately captured. Parametric studies on the effects of fuel jet velocity and swirl number on the swirl flame structure were done. Simulation of turbulent unconfined swirl flames shows that the structure of the swirl flames is consists of outer and inner recirculation zones. The outer recirculation zone occurs due to the bluff-body effect; meanwhile the inner recirculation zone occurs farther downstream due to reversed flow. For fuel jet velocity, an increase in the velocity causes suspension of the occurrence of secondary recirculation zone. In this case, for higher fuel jet velocity, longer time is required for the fuel jet to decay and recirculation zone to form. In addition to that, the flame height increases with increasing fuel jet velocity. On the other hand, an increase in swirl number causes an increase in flame width and flame height. Results from the simulation have also shown that for low swirl number of 0.3, recirculation zones were absent. As swirl number increases, the tangential momentum of air flow increase and therefore greater adverse pressure gradient will be produced. As a result, fuel jet is prohibited to travel farther downstream, and flow is reversed back into the recirculation zone.
format	Thesis
qualification_level	Master's degree
author	Mohd. Azli, Anis Athirah
author_facet	Mohd. Azli, Anis Athirah
author_sort	Mohd. Azli, Anis Athirah
title	Computational study of turbulent unconfined swirl flames
title_short	Computational study of turbulent unconfined swirl flames
title_full	Computational study of turbulent unconfined swirl flames
title_fullStr	Computational study of turbulent unconfined swirl flames
title_full_unstemmed	Computational study of turbulent unconfined swirl flames
title_sort	computational study of turbulent unconfined swirl flames
granting_institution	Universiti Teknologi Malaysia, Faculty of Mechanical Engineering
granting_department	Faculty of Mechanical Engineering
publishDate	2015
url	http://eprints.utm.my/id/eprint/53519/1/AnisAthirahMohdAzliMFKM2015.pdf
_version_	1747817571718004736

Computational study of turbulent unconfined swirl flames

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