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Study of the Structure of Turbulence in Accelerating Transitional Boundary Layers

1987
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Release : 1987
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Book Synopsis Study of the Structure of Turbulence in Accelerating Transitional Boundary Layers by : Michael F. Blair

Download or read book Study of the Structure of Turbulence in Accelerating Transitional Boundary Layers written by Michael F. Blair. This book was released on 1987. Available in PDF, EPUB and Kindle. Book excerpt: A combined experimental and analytical program has been conducted to examine transitional, accelerating boundary layer flows with high levels of freestream turbulence. An earlier program focused on measurement of transitional heat transfer distributions for four combinations of streamwise acceleration and freestream turbulence. The present program was designed to document the boundary layer turbulence structure and spectral distributions for the same four test conditions. The results from the present program have shown that transition in accelerating flows consists of an acceleration dominated stage of slowly developing intermittency followed by a second stage with the same general characteristics as zero-pressure-gradient transition. Conditionally sampled fluctuating velocity profile measurements indicated that the boundary layer turbulence was highly anisotropic in the early stages of transition. Conditionally sampled mean velocity measurements showed that within the intermittent turbulent patches the mean velocity profiles were very similar to those of an equilibrium turbulent boundary layer. Spectral distribution data indicated that preferred amplification of the most unstable (as predicted by linear stability theory) frequencies occurred upstream of the onset of transitional bursting. In addition to the experimental portion of this investigation, numerical experiments were undertaken to assess the ability of currently existing methods to predict heat transfer during transition in accelerating flows.

On the Three-Dimensional Structure of Boundary Layers Undergoing Transition to Turbulence

1985
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Release : 1985
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Book Synopsis On the Three-Dimensional Structure of Boundary Layers Undergoing Transition to Turbulence by : William S. Saric

Download or read book On the Three-Dimensional Structure of Boundary Layers Undergoing Transition to Turbulence written by William S. Saric. This book was released on 1985. Available in PDF, EPUB and Kindle. Book excerpt: Detailed experiments were performed for boundary layers undergoing transition to turbulence. The experiments utilized multiple hot wire anemometer techniques in combination with recently developed flow visualization and computational techniques. The use of a phase-correlated and conditionally sampled measurements permitted the study of the origin and evolution of the characteristic of transitional boundary layers. Fundamental transition mechanisms and the receptivity of the boundary layer to external disturbances that led to transition were studied.

Scientific and Technical Aerospace Reports

1995 Aeronautics
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Release : 1995
Genre : Aeronautics
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Book Synopsis Scientific and Technical Aerospace Reports by :

Download or read book Scientific and Technical Aerospace Reports written by . This book was released on 1995. Available in PDF, EPUB and Kindle. Book excerpt:

Experimental Investigation of Turbulent Prandtl Number and Reynolds Analogy in Transitional and Post-Transitional Boundary Layers

1993
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Release : 1993
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Book Synopsis Experimental Investigation of Turbulent Prandtl Number and Reynolds Analogy in Transitional and Post-Transitional Boundary Layers by :

Download or read book Experimental Investigation of Turbulent Prandtl Number and Reynolds Analogy in Transitional and Post-Transitional Boundary Layers written by . This book was released on 1993. Available in PDF, EPUB and Kindle. Book excerpt: The effects of elevated free-stream turbulence and streamwise acceleration on flow and thermal structures in transitional boundary layers have been investigated experimentally on a heated flat plate. The effects on the turbulent Prandtl number and Reynolds analogy were included in this study. The free-stream turbulence levels ranged from 0.5 to 7%, and the acceleration strengths, based on K, ranged from 0.39xl0 to the minus 6th power to 4.lxl0 to the minus 6th power. A three-wire probe was used to measure the detailed momentum and thermal boundary layer structures, including the streamwise and cross-stream velocity fluctuations, the temperature fluctuation, the Reynolds stresses, the Reynolds heat fluxes, the eddy viscosity, the turbulent thermal diffusivity and the turbulent Prandtl number. The results show that elevated free-stream turbulence values result in an earlier onset of transition and reduced length of transition, whereas streamwise acceleration delays the onset of transition and lengthens the transition region, even at elevated FSTI. Compared to streamwise acceleration, FSTI is the more dominant factor on flow and thermal structure in transitional boundary layers; however, streamwise acceleration significantly reduces the turbulent spot formation rate.

Elements of Transitional Boundary-Layer Flowlements

2018 Science
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Release : 2018
Genre : Science
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Book Rating : 980/5 ( reviews)

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Book Synopsis Elements of Transitional Boundary-Layer Flowlements by : Robert Edward Mayle

Download or read book Elements of Transitional Boundary-Layer Flowlements written by Robert Edward Mayle. This book was released on 2018. Available in PDF, EPUB and Kindle. Book excerpt: Second Enhanced Edition Suitable for advanced-level courses or an independent study in fluid mechanics, this text by an expert in the field provides the basic aspects of laminar-to-turbulent flow transition in boundary layers. Logically organized into three major parts, the book covers pre- and post-transitional flow, transitional flow, and several advanced topics in periodically disturbed transitional flow. Some of the subjects covered within the book include high-frequency unsteady laminar flow, turbulent flow, natural transition, bypass transition, turbulent spot theory, turbulent spot kinematics and production, correlations for the onset and rate of transition, global and conditional averaging, transitional flow models, wakeinduced transition, multimode transition, and separated-flow transition. Containing some 202 figures (all drawn by the author), 28 tables, 12 appendices, a supplement on tensors, and an extensive bibliography, the 415 page book provides a wealth of data and information about the subject.

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