An Experimental Investigation of Shear Layer Mixing in Supersonic Flows PDF Download

Author: Gary Alan Sullins
Publisher:
ISBN:
Category : Aerodynamics, Supersonic
Languages : en
Pages : 228

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 29

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A shear layer formed by the merging of two different mass density and velocity, supersonic, inert gas streams (Ar and He) was investigated using both intrusive (probes) and non-intrusive (laser-based) techniques. Interpretations based upon mean pitot pressure surveys, namely shear layer growth rate and compressibility agree with established data. An aspirating probe in conjunction with a mass spectrometer comprised a gas sampling system for ultimately obtaining concentration profiles. Rapid scanning of such flows is possible with such a technique but additional efforts are required to make quantitative concentration assignments. The technique does, however, provide a means of qualitatively assessing mixing rates. Finally planar laser-induced fluorescence (PLIF) was used to establish spatially and temporally resolved images of the shear layer. Obtained images demonstrate the usefulness of PLIF to qualitatively monitor turbulent mixing phenomena in supersonic flows. 17 refs., 14 figs.

Author: Noel T. Clemens
Publisher:
ISBN:
Category :
Languages : en
Pages : 470

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Author: Steven William Vavrik
Publisher:
ISBN:
Category :
Languages : en
Pages : 274

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Author: Hideo Ikawa
Publisher:
ISBN:
Category :
Languages : en
Pages : 39

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The effect of compressibility on the mixing layer was investigated at Mach number 2.47. Pitot pressure, static pressure and hot-wire surveys were made to investigate the mean flow and the fluctuation quantities. Similarities between supersonic and incompressible mixing layers are observed in normalized velocity profile, normalized power spectral density distribution and convection velocity distribution. Spreading rate, normalized shear stress and velocity fluctuation were found to be appreciably smaller than the respective incompressible results; e.g., the momentum thickness growth rates are 0.0073 and 0.035 for supersonic and incompressible flows, respectively. The difference between free and wall-bounded mixing layers is discussed. Development of turbulence structure of mixing layer with increasing Reynolds number was also investigated. (Author).

Author: Hall, Jeffery L
Publisher: Ann Arbor, Mich. : University Microfilms International
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 139

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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.

Author: Jeffery Lawrence Hall
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 139

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Book Description
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.

Author: P. J. Wantuck
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Ning Zhuang
Publisher:
ISBN:
Category :
Languages : en
Pages : 176

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The study of supersonic cavity flows is of interest both from fundamental fluid dynamics and practical perspectives. The complex nature of this flowfield, consisting of compressible shear layers, compression/expansion waves, and fluid-acoustic interactions, makes it a rich problem to study. A detailed experimental study of supersonic flow (M=1.5 to 2) over a range of three-dimensional rectangular cavities (L/D=1 to 5.2) was conducted. The measurements included unsteady surface pressure measurements, particle image velocimetry, and flow visualization using shadowgraph and schlieren. Large-scale structures in the shear layer and a large recirculation zone in the cavity was observed. Spatial and temporal mode switching was also observed, the nature being different for short and long cavities. The shear layer characteristics of the two cavities are very different in term of curvature and growth. Supersonic microjets were used at the leading edge of the cavities to suppress the resonance in the flow. With a minimal mass flux (0.15%), the activation of microjets led to a large reduction in cavity tones (20 dB) and overall sound pressure levels (9dB). In addition, the microjet injection enhanced the shear layer mixing and reduced the velocity fluctuation in the cavities. The significant reductions together with the low mass flux requirements make this a potentially viable technique for full-scale, practical applications.

Author: Riccardo Bonazza
Publisher:
ISBN: 9783319168395
Category :
Languages : en
Pages :

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This proceedings present the results of the 29th International Symposium on Shock Waves (ISSW29) which was held in Madison, Wisconsin, U.S.A., from July 14 to July 19, 2013. It was organized by the Wisconsin Shock Tube Laboratory, which is part of the College of Engineering of the University of Wisconsin-Madison. The ISSW29 focused on the following areas: Blast Waves, Chemically Reactive Flows, Detonation and Combustion, Facilities, Flow Visualization, Hypersonic Flow, Ignition, Impact and Compaction, Industrial Applications, Magnetohydrodynamics, Medical and Biological Applications, Nozzle Flow, Numerical Methods, Plasmas, Propulsion, Richtmyer-Meshkov Instability, Shock-Boundary Layer Interaction, Shock Propagation and Reflection, Shock Vortex Interaction, Shock Waves in Condensed Matter, Shock Waves in Multiphase Flow, as well as Shock Waves in Rarefield Flow. The two Volumes contain the papers presented at the symposium and serve as a reference for the participants of the ISSW 29 and individuals interested in these fields.