Jet noise : aeroacoustic distribution of a subsonic co-axial jet
Kiran, Amit (2008) Jet noise : aeroacoustic distribution of a subsonic co-axial jet. PhD thesis, University of Warwick.
WRAP_THESIS_Kiran_2008.pdf - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader
Official URL: http://webcat.warwick.ac.uk/record=b2341129~S15
The noise generated by aircraft can be easily heard by those living under the flight path of passenger or cargo carriers. It is considered an environmental pollutant
and is treated as such by the International Civil Aviation Organization
(ICAO) who monitor and review noise levels. The ICAO imposes substantial
fines on those carriers who do not adhere to the decibel limitations. With the
new limit or `stage' enforced in 2006, aircraft manufacturers (including jet engine
manufacturers) are seeking ways to reduce the noise created by an aircraft.
A 1/150th scale model, based on the exit geometry typically found on commercial
jet engines, was designed and manufactured at Warwick. The laboratory
jet flow conditions operated at 0.7 Mach. The work presented in this thesis
looks at the noise generated in a subsonic, co-
owing jet, with particular focus
given to the distribution sound sources from 5 kHz to 80 kHz (0.375 St to 6.0 St).
An acoustic mirror mounted on a motorized 3-way traverse measured radiated
sound in the co-flowing jet to produce 2D sound source maps. This is done using
combinations of smooth cowl and chevrons for the core and bypass nozzles. For
frequencies less than 30 kHz, a reduction of noise was observed using the bypass
chevron nozzle compared with the bypass smooth cowl nozzle.
Laser Doppler Anemometry (LDA) was used to reveal the 2D
flow dynamics of
the jet, supporting the acoustic distribution results with velocity profiles of the flow. The change in the flow dynamics with different nozzle combinations is discussed
and different regions of the flow were identified.
|Item Type:||Thesis or Dissertation (PhD)|
|Subjects:||T Technology > TL Motor vehicles. Aeronautics. Astronautics|
|Library of Congress Subject Headings (LCSH):||Airplanes -- Noise, Jet engines, Jets -- Fluid dynamics, Jet nozzles, Nozzles -- Fluid dynamics|
|Institution:||University of Warwick|
|Theses Department:||School of Engineering|
|Extent:||xxviii, 305 leaves : ill., charts|
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