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A computational and experimental investigation of film cooling effectiveness Zhou, Jian Ming
Abstract
Film cooling is a technique used to protect turbine blades or other surfaces from a high temperature gas stream. This thesis presents an experimental and computational study of film cooling effectiveness based on two film cooling models in which coolant is injected onto a flat plate from a uniform slot (2-D) and a row of discrete holes (3-D). The existing turbulence models and near-wall turbulence treatments are evaluated. The transport equations are solved by the control volume finite difference and multigrid formulation, and the flow and heat transfer near the injection orifices and the film cooled wall are resolved by grid refinement. To verify the numerical model, physical experiments based on the heat-mass transfer analogy were carried out. Film cooling effectiveness and flow fields were measured using a flame ionization detector and hot-wire anemometry. For the 2-D model, the turbulence is modelled by the multiple-time-scale (M-T-s) turbulence model combined with the low-Re k turbulence model in the viscosity-affected near-wall region. Comparisons of the film cooling effectiveness and flow fields between computations and experiments for mass flow rate (RM) of 0.2,0.4,0.6 show that the M-T S model provides better agreement than the k-E model especially at high RM. Also, the low-Re k turbulence model used in the near-wall region allows for grid refinement near the film cooled wall, giving better flow and heat transfer predictions downstream of injection than the wall function method. For the 3-D model, a non-isotropic k-E turbulence model is used in combination with the low-Re k turbulence model as the near-wall treatment. Comparison of the spanwise averaged film cooling effectiveness between computation and experiment shows good agreement for mass flow ratios of 0.2, 0.4; however, the numerical values are consistently lower than the measured results for RM = 0.8. Comparison of the mean velocity and turbulence kinetic energy shows good agreement, especially near the injection. Further work to extend the M-T-S model to the 3-D model is suggested. Parametric tests of film cooling by single and double-row injection were carried out computationally to investigate the effects of mass flow rate, injection direction, hole spacing and stagger on the film cooling effectiveness. The superior performance of the lateral injection at high mass flow ratio, mainly near the injection orifice, is demonstrated. For the double-row injection, consistently better performance of the arrangement with stagger factor A/d=3 is found for the range of parameters investigated.
Item Metadata
Title |
A computational and experimental investigation of film cooling effectiveness
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1994
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Description |
Film cooling is a technique used to protect turbine blades or other surfaces from a high
temperature gas stream. This thesis presents an experimental and computational study of
film cooling effectiveness based on two film cooling models in which coolant is injected
onto a flat plate from a uniform slot (2-D) and a row of discrete holes (3-D). The existing
turbulence models and near-wall turbulence treatments are evaluated. The transport
equations are solved by the control volume finite difference and multigrid formulation, and
the flow and heat transfer near the injection orifices and the film cooled wall are resolved
by grid refinement. To verify the numerical model, physical experiments based on the
heat-mass transfer analogy were carried out. Film cooling effectiveness and flow fields
were measured using a flame ionization detector and hot-wire anemometry.
For the 2-D model, the turbulence is modelled by the multiple-time-scale (M-T-s)
turbulence model combined with the low-Re k turbulence model in the viscosity-affected
near-wall region. Comparisons of the film cooling effectiveness and flow fields between
computations and experiments for mass flow rate (RM) of 0.2,0.4,0.6 show that the M-T
S model provides better agreement than the k-E model especially at high RM. Also, the
low-Re k turbulence model used in the near-wall region allows for grid refinement near the
film cooled wall, giving better flow and heat transfer predictions downstream of injection
than the wall function method.
For the 3-D model, a non-isotropic k-E turbulence model is used in combination
with the low-Re k turbulence model as the near-wall treatment. Comparison of the
spanwise averaged film cooling effectiveness between computation and experiment shows
good agreement for mass flow ratios of 0.2, 0.4; however, the numerical values are
consistently lower than the measured results for RM = 0.8. Comparison of the mean
velocity and turbulence kinetic energy shows good agreement, especially near the
injection. Further work to extend the M-T-S model to the 3-D model is suggested.
Parametric tests of film cooling by single and double-row injection were carried
out computationally to investigate the effects of mass flow rate, injection direction, hole
spacing and stagger on the film cooling effectiveness. The superior performance of the
lateral injection at high mass flow ratio, mainly near the injection orifice, is demonstrated.
For the double-row injection, consistently better performance of the arrangement with
stagger factor A/d=3 is found for the range of parameters investigated.
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Extent |
4524740 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-04-15
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0080884
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1994-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.