Entropy noise caused by combustors increases rapidly with rising Mach number in the nozzle downstream of the combustion chamber. This is experimentally shown with a dedicated test facility, in which entropy waves are generated in a controlled way by unsteady electrical heating of fine platinum wires immersed in the flow. Downstream of the heating module called entropy wave generator (EWG), the pipe flow is accelerated through a convergent-divergent nozzle with a maximum Mach number of 1.2 downstream of the nozzle throat. Parameters like mass flux of the flow, nozzle Mach number, amount of heating energy, excitation mode (periodic, pulsed, or continuously), and propagation length between EWG and nozzle have been varied for the analysis of the generated entropy noise. The results are compared with the results of a one-dimensional theory found in early literature.
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January 2008
Research Papers
Fundamental Mechanism of Entropy Noise in Aero-Engines: Experimental Investigation
Friedrich Bake,
Friedrich Bake
Department of Engine Acoustics, Institute of Propulsion Technology,
e-mail: friedrich.bake@dlr.de
German Aerospace Center (DLR)
, Mueller-Breslau-Strasse 8, 10623 Berlin, Germany
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Nancy Kings,
Nancy Kings
Department of Engine Acoustics, Institute of Propulsion Technology,
German Aerospace Center (DLR)
, Mueller-Breslau-Strasse 8, 10623 Berlin, Germany
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Ingo Roehle
Ingo Roehle
Department of Engine Acoustics, Institute of Propulsion Technology,
German Aerospace Center (DLR)
, Mueller-Breslau-Strasse 8, 10623 Berlin, Germany
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Friedrich Bake
Department of Engine Acoustics, Institute of Propulsion Technology,
German Aerospace Center (DLR)
, Mueller-Breslau-Strasse 8, 10623 Berlin, Germanye-mail: friedrich.bake@dlr.de
Nancy Kings
Department of Engine Acoustics, Institute of Propulsion Technology,
German Aerospace Center (DLR)
, Mueller-Breslau-Strasse 8, 10623 Berlin, Germany
Ingo Roehle
Department of Engine Acoustics, Institute of Propulsion Technology,
German Aerospace Center (DLR)
, Mueller-Breslau-Strasse 8, 10623 Berlin, GermanyJ. Eng. Gas Turbines Power. Jan 2008, 130(1): 011202 (6 pages)
Published Online: January 9, 2008
Article history
Received:
May 4, 2007
Revised:
May 7, 2007
Published:
January 9, 2008
Citation
Bake, F., Kings, N., and Roehle, I. (January 9, 2008). "Fundamental Mechanism of Entropy Noise in Aero-Engines: Experimental Investigation." ASME. J. Eng. Gas Turbines Power. January 2008; 130(1): 011202. https://doi.org/10.1115/1.2749286
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