Type of Document	Master's Thesis
Author	Hendricks, Adam Gerald
Author's Email Address	agh@vt.edu
URN	etd-12192003-144627
Title	Determination of Flame Dynamics for Unsteady Combustion Systems using Tunable Diode Laser Absorption Spectroscopy
Degree	Master of Science
Department	Mechanical Engineering
Advisory Committee	Advisor Name Title Vandsburger, Uri Committee Chair Baumann, William T. Committee Member Khanna, Vivek K. Committee Member Saunders, William R. Committee Member
Keywords	Flame Dynamics Tunable Diode Laser Absorption Spectroscopy Combustion Thermoacoustic Instabilities
Date of Defense	2003-12-15
Availability	unrestricted
Abstract Lean, premixed combustion has enjoyed increased application due to the need to reduce pollutant emissions. Unfortunately, operating the flame at lean conditions increases susceptibility to thermoacoustic (TA) instability. Self-excited TA instabilities are a result of the coupling of the unsteady heat release rate of the flame with the acoustics of the combustion chamber. The result is large pressure oscillations that degrade performance and durability of combustion systems. Industry currently has no reliable tool to predict instabilities a priori. CFD simulations of full-scale, turbulent, reacting flows remain unrealizable. The work in this paper is part of a study that focuses on developing compact models of TA instabilities, i.e. acoustics and flame dynamics. Flame dynamics are defined as the response in heat release to acoustic perturbations. Models of flame dynamics can be coupled with models of combustor enclosure acoustics to predict TA instabilities. In addition, algorithms to actively control instabilities can be based on these compact models of flame dynamics and acoustics. The work outlined in this thesis aims at determining the flame dynamics model experimentally. Velocity perturbations are imparted on laminar and turbulent flames via a loudspeaker upstream of the flame. The response of the flame is observed through two measurements. Hydroxyl radical (OH*) chemiluminescence indicates the response in chemical reaction rate. Tunable Diode Laser Absorption Spectroscopy (TDLAS), centered over two water absorption features, allows a dynamic measurement of the product gas temperature. The response in product gas temperature directly relates to the enthalpy fluctuations that couple to the acoustics. Experimental frequency response functions of a laminar, flat-flame burner and a turbulent, swirl-stabilized combustor will be presented as well as empirical low-order models of flame dynamics.
Files	Filename       Size       Approximate Download Time (Hours:Minutes:Seconds)     28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access    front_matter.pdf 208.01 Kb 00:00:57 00:00:29 00:00:26 00:00:13 00:00:01   MS_A1_error.pdf 131.18 Kb 00:00:36 00:00:18 00:00:16 00:00:08 < 00:00:01   MS_B1_spectdat.pdf 206.06 Kb 00:00:57 00:00:29 00:00:25 00:00:12 00:00:01   MS_B2_wavescan.pdf 105.43 Kb 00:00:29 00:00:15 00:00:13 00:00:06 < 00:00:01   MS_ch1_introduction.pdf 225.59 Kb 00:01:02 00:00:32 00:00:28 00:00:14 00:00:01   MS_ch2_litreview.pdf 221.24 Kb 00:01:01 00:00:31 00:00:27 00:00:13 00:00:01   MS_ch3_expsetup.pdf 830.21 Kb 00:03:50 00:01:58 00:01:43 00:00:51 00:00:04   MS_ch4_LFD.pdf 2.15 Mb 00:09:56 00:05:06 00:04:28 00:02:14 00:00:11   MS_ch5_TFD.pdf 634.23 Kb 00:02:56 00:01:30 00:01:19 00:00:39 00:00:03   MS_ch6_future.pdf 130.67 Kb 00:00:36 00:00:18 00:00:16 00:00:08 < 00:00:01   MS_C_equipment.pdf 62.07 Kb 00:00:17 00:00:08 00:00:07 00:00:03 < 00:00:01   MS_D_drwg.pdf 468.87 Kb 00:02:10 00:01:06 00:00:58 00:00:29 00:00:02   MS_E_circuits.pdf 172.17 Kb 00:00:47 00:00:24 00:00:21 00:00:10 < 00:00:01   MS_F_TDLASmanual.pdf 249.85 Kb 00:01:09 00:00:35 00:00:31 00:00:15 00:00:01   vita.pdf 107.53 Kb 00:00:29 00:00:15 00:00:13 00:00:06 < 00:00:01

If you have questions or technical problems, please Contact DLA.