Structure of the Compressible Turbulent Shear Layer
Structure of the Compressible Turbulent Shear Layer

Author: Dimitri Papamoschou

Publisher:

Published: 1989

Total Pages: 13

ISBN-13:

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The large-scale structure of the turbulent compressible shear layer is investigated in a two-stream supersonic wind tunnel through a series of experiments. Double-exposure schlieren photography reveals that the two convective Mach numbers, corresponding to each side of the shear layer, are very different, one sonic or supersonic and the other low subsonic. This contradicts, the current isentropic model of the structure which predicts them to be equal or very close. It is shown that addition of shock-wave effects to that model allows for the asymmetric trends observed in the experiments. An inclined view of the flow provides sketchy information about the spanwise orientation of the large-scale structure and does not reveal any pronounced obliquity. Attempts to enhance mixing by modifying the trailing edge were unsuccessful. (AW).

An Experimental Investigation of Structure, Mixing and Combustion in Compressible Turbulent Shear Layers [microform]
An Experimental Investigation of Structure, Mixing and Combustion in Compressible Turbulent Shear Layers [microform]

Author: Hall, Jeffery L

Publisher: Ann Arbor, Mich. : University Microfilms International

Published: 1991

Total Pages: 139

ISBN-13:

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Two-dimensional, compressible, turbulent shear layers are studied in a new wind tunnel facility. Both reacting and non-reacting flows are investigated, with one free stream velocity supersonic and the other subsonic. The combustion experiments are based on use of low concentrations of hydrogen, nitric oxide and fluorine gases. Side-view Schlieren photographs of these reacting and non-reacting flows appear devoid of the 2-D, large scale structures seen in incompressible flow. Comparison with all-subsonic flows produced in the same facility suggests that this lack of two-dimensional structure is due to the presence of the supersonic high-speed free stream velocity. Travelling shock and expansion waves are observed in the high compressibility flows, evidently created by turbulent structures convecting at supersonic velocities. Such waves are seen only in the low-speed fluid, with apparent convection velocities much higher than those predicted on the basis of isentropic pressure-matching arguments. The measured shear layer growth rates agree with previous results by other experiments, except for a few cases at low compressibility and low density ratio. The fast chemistry regime is attained in some of the high compressibility flows tested. 'Flip' experiments conducted in this regime indicated that the volume fraction of mixed fluid in the layer is substantially reduced as compared to previous incompressible results. These same flip experiments also reveal that compressibility significantly alters the entrainment ratio.

An Experimental Investigation of Structure, Mixing and Combustion in Compressible Turbulent Shear Layers
An Experimental Investigation of Structure, Mixing and Combustion in Compressible Turbulent Shear Layers

Author: Jeffery Lawrence Hall

Publisher:

Published: 1991

Total Pages: 139

ISBN-13:

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Two-dimensional, compressible, turbulent shear layers are studied in a new wind tunnel facility. Both reacting and non-reacting flows are investigated, with one free stream velocity supersonic and the other subsonic. The combustion experiments are based on use of low concentrations of hydrogen, nitric oxide and fluorine gases. Side-view Schlieren photographs of these reacting and non-reacting flows appear devoid of the 2-D, large scale structures seen in incompressible flow. Comparison with all-subsonic flows produced in the same facility suggests that this lack of two-dimensional structure is due to the presence of the supersonic high-speed free stream velocity. Travelling shock and expansion waves are observed in the high compressibility flows, evidently created by turbulent structures convecting at supersonic velocities. Such waves are seen only in the low-speed fluid, with apparent convection velocities much higher than those predicted on the basis of isentropic pressure-matching arguments. The measured shear layer growth rates agree with previous results by other experiments, except for a few cases at low compressibility and low density ratio. The fast chemistry regime is attained in some of the high compressibility flows tested. 'Flip' experiments conducted in this regime indicated that the volume fraction of mixed fluid in the layer is substantially reduced as compared to previous incompressible results. These same flip experiments also reveal that compressibility significantly alters the entrainment ratio.

Turbulent Shear Layers in Supersonic Flow
Turbulent Shear Layers in Supersonic Flow

Author: Alexander J. Smits

Publisher: Springer Science & Business Media

Published: 2006-05-11

Total Pages: 418

ISBN-13: 0387263055

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A good understanding of turbulent compressible flows is essential to the design and operation of high-speed vehicles. Such flows occur, for example, in the external flow over the surfaces of supersonic aircraft, and in the internal flow through the engines. Our ability to predict the aerodynamic lift, drag, propulsion and maneuverability of high-speed vehicles is crucially dependent on our knowledge of turbulent shear layers, and our understanding of their behavior in the presence of shock waves and regions of changing pressure. Turbulent Shear Layers in Supersonic Flow provides a comprehensive introduction to the field, and helps provide a basis for future work in this area. Wherever possible we use the available experimental work, and the results from numerical simulations to illustrate and develop a physical understanding of turbulent compressible flows.

Turbulent Shear Layers in Supersonic Flow
Turbulent Shear Layers in Supersonic Flow

Author: Alexander J. Smits

Publisher: A I P Press

Published: 1996

Total Pages: 384

ISBN-13:

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Using the most recent data, this text describes the physical mechanisms of turbulent supersonic flows, emphasizing the similarities and differences between compressible and incompressible flows. DLC: Aerodynamics, Supersonic.

The Structure of Turbulent Shear Flow
The Structure of Turbulent Shear Flow

Author: A. A. R. Townsend

Publisher: Cambridge University Press

Published: 1976

Total Pages: 450

ISBN-13: 9780521298193

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Develops a physical theory from the mass of experimental results, with revisions to reflect advances of recent years.

Compressibility, Turbulence and High Speed Flow
Compressibility, Turbulence and High Speed Flow

Author: Thomas B. Gatski

Publisher: Academic Press

Published: 2013-03-05

Total Pages: 343

ISBN-13: 012397318X

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Compressibility, Turbulence and High Speed Flow introduces the reader to the field of compressible turbulence and compressible turbulent flows across a broad speed range, through a unique complimentary treatment of both the theoretical foundations and the measurement and analysis tools currently used. The book provides the reader with the necessary background and current trends in the theoretical and experimental aspects of compressible turbulent flows and compressible turbulence. Detailed derivations of the pertinent equations describing the motion of such turbulent flows is provided and an extensive discussion of the various approaches used in predicting both free shear and wall bounded flows is presented. Experimental measurement techniques common to the compressible flow regime are introduced with particular emphasis on the unique challenges presented by high speed flows. Both experimental and numerical simulation work is supplied throughout to provide the reader with an overall perspective of current trends. - An introduction to current techniques in compressible turbulent flow analysis - An approach that enables engineers to identify and solve complex compressible flow challenges - Prediction methodologies, including the Reynolds-averaged Navier Stokes (RANS) method, scale filtered methods and direct numerical simulation (DNS) - Current strategies focusing on compressible flow control

An Experimental Investigation of Organized Structure and Mixing in Compressible Turbulent Free Shear Layers
An Experimental Investigation of Organized Structure and Mixing in Compressible Turbulent Free Shear Layers

Author: Nathan Lee Messersmith

Publisher:

Published: 1992

Total Pages: 474

ISBN-13:

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The large scale structure and scalar transport characteristics of compressible turbulent mixing layers have been experimentally investigated at various levels of compressibility in order to study the fundamental effects of compressibility on the nature of the mixing layer. Nonintrusive optical diagnostic techniques were employed to image the large structures. Both Mie scattering from condensed ethanol droplets and laser-induced fluorescence from seeded nitric oxide were used. The LIF experiments were utilized to avoid potential particle dynamics effects associated with the Mie scattering experiments. Sizeable ensembles of digital images were collected for a variety of seeding styles, image planes and at three distinct flow conditions. Analysis of the samples provided mean and standard deviation profiles, two-dimensional spatial covariance fields and passive scalar probability density functions. In the transverse image plane, the dimensionless structure size and eccentricity increased, while the angular orientation of the structures with respect to the streamwise flow direction decreased, as the relative Mach number increased. Oblique views revealed significant three-dimensionality, and the structures imaged in this view also increased in dimensionless size with compressibility. Very little difference in the total probabilities of finding mixed fluid within the shear layer was found for flows with relative Mach numbers of 0.63 and 1.49. A relative Mach number 0.98 flow, however, demonstrated substantially lower mixed fluid probabilities, concomitant with a very high peak standard deviation. Instability mode interactions may be the cause of the disturbed nature of the mixing layer at this condition. The results from the Mie scattering and laser-induced fluorescence experiments for similar shear layer conditions were very comparable.

Eddy Structure Identification in Free Turbulent Shear Flows
Eddy Structure Identification in Free Turbulent Shear Flows

Author: J.P. Bonnet

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 504

ISBN-13: 9401120986

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The existence and crucial role played by large-scale, organized motions in turbulent flows are now recognized by industrial, applied and fundamental researchers alike. It has become increasingly evident that coherent structures influence mixing, noise, vibration, heat transfer, drag, etc... The accelera tion of the development of both experimental and computational programs devoted to this topic has been evident at several recent international meet ings. One of the first questions which experimentalists or numerical analysts are faced with is: how can these structures be separated from the background turbulence? This is a nontrivial task because the coherent structures are gen erally embedded in a random field and the technique used to determine when and where certain structures are passing, or their averaged characteristics (in the more probable or dominant role sense) is directly related to the definition of the coherent structure. Several methods or approaches are available and the choice of a particular one is generally dependent on the desired informa tion. This choice depends not only on the definition of the structure, but also on the experimental and numerical capabilities available to the researcher.