Title page for ETD etd-12192003-144627


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.

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  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

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