An experimental study of near wall flow parameters in the blade end-wall corner region.
Item
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Title
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An experimental study of near wall flow parameters in the blade end-wall corner region.
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Identifier
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AAI9000015
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identifier
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9000015
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Creator
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Bhargava, Rakesh Kumar.
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Contributor
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Adviser: Rishi Raj
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Date
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1989
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Language
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English
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Publisher
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City University of New York.
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Subject
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Engineering, Mechanical
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Abstract
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The objective of the present study was to experimentally investigate the near wall flow parameters in the blade end-wall corner region. The blade end-wall corner region was simulated by mounting an airfoil section (NACA 65-015 base profile) symmetric blades on both sides of the flat plate with semi-circular leading edge. An experimental investigation was also extended to study the combined effect of initial roughness and increased level of free stream turbulence on the development of a two-dimensional turbulent boundary layer in the absence of the blade.;The changes in the initial flow conditions significantly influenced the development of a two-dimensional turbulent boundary layer. The increase in free stream turbulence level, in the presence of initial roughness, had an opposite effect on the variation of different mean flow characteristics relative to the case when initial roughness was absent.;At different streamwise stations, in the blade end-wall corner region, the mean values of surface static pressure varied more on the end-wall surface than on the blade surface. The magnitude of the wall shear stress in the blade end-wall corner region increased significantly in the close vicinity of the corner line. The maximum value of the wall shear stress and its location from the corner line, on both the surfaces forming the corner region, were observed to change along the corner. These observed changes in the maximum values of the wall shear stress and its location from the corner line could be associated with the stretching and attenuation of the horseshoe vortex. The wall shear stress vectors in the blade end-wall corner region were observed to be more skewed on the end-wall surface as compared to that on the blade surface.;The values of wall pressure fluctuation intensity in the blade end-wall corner region were found to be influenced by the changes in the strength of the horseshoe vortex. The spectral content of the wall pressure fluctuation increased, at any streamwise station, as the blade surface was approached. The correlation of the wall pressure fluctuation with the velocity fluctuation indicated, in general, higher values of correlation coefficient in the inner region as compared to the outer region of the shear layer. Also, the values of wall pressure-velocity correlation coefficient in the blade end-wall corner region decreased and increased in the presence of favorable and adverse pressure gradients, respectively, in the streamwise direction.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
