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DGV flow field analysis and OH* chemiluminescence imaging in an industrial combustor operating under thermo-acoustic combustion oscillations

Stockhausen, Guido and Heinze, Johannes and Fischer, Michael and Müller, Martin and Blomeyer, Malte and Buch, Stefan and Terjung, Lars (2004) DGV flow field analysis and OH* chemiluminescence imaging in an industrial combustor operating under thermo-acoustic combustion oscillations. DLR/ONERA Annex II Meeting 2004, 2004-04-06 - 2004-04-07, Köln.

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Abstract

On the way towards a low emission combustion a possible solution seems to be the use of leaner fuel mixtures. But the main problem occurring at full power conditions are the thermo-acoustic combustion oscillations which can not be tolerated. In order to examine the reasons for that problem we applied two different measurement techniques – DGV and OH* imaging – to an industrial sized combustion chamber operating at atmospheric pressure conditions. For the DGV measurements in hot environments the biggest challenge is to overcome the strong background luminosity. Therefore we applied a self-developed pulse laser system with suitable DGV characteristics such as high power (~1mJ), narrow bandwidth (<1MHz) and frequency stability (single-mode operation) together with a gated camera system. To record phase resolved measurements we extracted a trigger signal from the output of a piezo pressure transducer placed in front of the burner outlet. Another important aspect of applying the DGV technique is the addition of seeding particles to the flow. Therefore we used AlO-powder in a solid particle seeding generator which contains a sintered glass filter and a stirring device. Three light sheets were guided through small slits from the sidewalls into the measurement area. A cooled endoscope was mounted inside the combustor looking directly onto the burner head. With this arrangement we obtained all three velocity components for stationary conditions and for different phase angles during an oscillation cycle. The results show that under stationary conditions the flow field is nearly rotational symmetrically with a distinct recirculation zone. In contrast to the stationary flow the phase resolved measurements revealed a drastic change from a combustion with recirculation to a complete forward directed flow depending on the phase angle. In addition to this flow field measurements we recorded heat release images. The underlying principle of this technique is the use of the chemical excitation of the OH-radical as an indicator of the heat release. This is a simple imaging technique which uses only an intensified CCD-camera together with a wavelength filter permeable for OH* fluorescence. We examined the transition from stationary conditions to combustion oscillations with the help of those heat release images. During combustion oscillations the maximum of the heat release is connected to the development of a maximum velocity gradient between the recirculation zone and the outer swirled flow. The minimum of the heat release corresponds to a complete forward directed flow with a vanishing recirculation zone.

Document Type:Conference or Workshop Item (Paper)
Title:DGV flow field analysis and OH* chemiluminescence imaging in an industrial combustor operating under thermo-acoustic combustion oscillations
Authors:
AuthorsInstitution or Email of Authors
Stockhausen, GuidoUNSPECIFIED
Heinze, JohannesUNSPECIFIED
Fischer, MichaelUNSPECIFIED
Müller, MartinUNSPECIFIED
Blomeyer, MalteSiemens PG, Mühlheim/Ruhr
Buch, StefanSiemens PG, Mühlheim/Ruhr
Terjung, LarsSiemens PG, Mühlheim/Ruhr
Date:2004
Refereed publication:No
In SCOPUS:No
In ISI Web of Science:No
Status:Published
Keywords:OH* fluorescence, DGV, flow field analysis, OH* chemiluminescence, thermo-acoustic combustion oscillations
Event Title:DLR/ONERA Annex II Meeting 2004
Event Location:Köln
Event Type:international Conference
Event Dates:2004-04-06 - 2004-04-07
Organizer:DLR Institut für Antriebstechnik, Abteilung Triebwerksmesstechnik
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Aeronautics
HGF - Program Themes:Propulsion Systems
DLR - Research area:Aeronautics
DLR - Program:L ER - Engine Research
DLR - Research theme (Project):L - Virtual Engine and Validation Methods
Location: Köln-Porz
Institutes and Institutions:Institute of Propulsion Technology > Engine Measurement Systems
Deposited By:INVALID USER
Deposited On:20 Mar 2006
Last Modified:14 Jan 2010 21:05

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