Optical instrumentation for fluid flow in gas turbines
Burnett, Mark (2000) Optical instrumentation for fluid flow in gas turbines. PhD thesis, University of Warwick.
WRAP_THESIS_Burnett_2000.pdf - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader
Official URL: http://webcat.warwick.ac.uk/record=b1371240~S15
Both a novel shearing interferometer and the first demonstration of particle image velocimetry
(PIV) to the stator-rotor gap of a spinning turbine cascade are presented. Each of these
techniques are suitable for measuring gas turbine representative flows.
The simple interferometric technique has been demonstrated on a compressor representative
flow in a 2-D wind tunnel. The interferometer has obvious limitations, as it requires a clear line
of sight for the integration of refractive index along an optical path. Despite this, it is a credible
alternative to schlieren or shadowgraph in that it provides both qualitative visualisation and a
quantitative measurement of refractive index and the variables to which it is dependent without
the vibration isolation requirements of beam splitting interferometry.
The 2-D PIV measurements have been made in the stator-rotor gap of the MTI high-pressure
turbine stage within DERA's Isentropic Light Piston Facility (lLPF). The measurements were
made at full engine representative conditions adjacent to a rotor spinning at 8200 rpm. This is a
particularly challenging application due to the complex geometry and random and periodic
effects generated as the stator wake interacts with the adjacent spinning rotor. The application is
further complicated due to the transient nature of the facility. The measurements represent a 2-
D, instantaneous, quantitative description of the unsteady flow field and reveal evidence of
shocks and wakes. The estimated accuracy after scaling, timing, particle centroid and particle
lag errors have been considered is ± 5%. Non-smoothed, non-time averaged measurements are
qualitatively compared with a numerical prediction generated using a 2-D unsteady flow solver
(prediction supplied by DERA). A very close agreement has been achieved.
A novel approach to characterising the third component of velocity from the diffraction rings of
a defocusing particle viewed through a single camera has been explored. This 3-D PIV
technique has been demonstrated on a nozzle flow but issues concerning the aberrations of the
curved test section window of the turbine cascade could not be resolved in time for testing on
the facility. Suggestions have been made towards solving this problem.
Recommendations are also made towards the eventual goal of revealing a temporally and
spatially resolved 3-D velocity distribution of the stator wake impinging on the passing rotor.
|Item Type:||Thesis or Dissertation (PhD)|
|Subjects:||T Technology > TJ Mechanical engineering and machinery|
|Library of Congress Subject Headings (LCSH):||Gas-turbines, Fluid dynamics, Interferometers, Particle image velocimetry|
|Official Date:||September 2000|
|Institution:||University of Warwick|
|Theses Department:||School of Engineering|
|Sponsors:||Engineering and Physical Sciences Research Council (EPSRC) ; City of London (England). Corporation|
|Extent:||xxiv, 288 p.|
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