Wall Jet Turbulence And Mixing Control By Way Of A Pulsed Inlet Velocity
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Wall Jet Turbulence And Mixing Control By Way Of A Pulsed Inlet Velocity
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Author : Cristale D. Garnica Vallejo
language : en
Publisher:
Release Date : 2019
Wall Jet Turbulence And Mixing Control By Way Of A Pulsed Inlet Velocity written by Cristale D. Garnica Vallejo and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with Aerospace engineering categories.
"Understanding wall-jet-induced turbulence and mixing is an important challenge in modern engineering, as drag reduction and mixing enhancement are attainable by modifying the flow development. Simulations are performed to investigate the effect on skin friction and flow mixing due to introducing controlled perturbations, at the initial shear layer of a planar wall-jet using jet inlet cyclic pulsing. The billow production by the Kelvin-Helmholtz instability, the instability that drives turbulence in a wall-jet, is modified by the excitation of the inlet velocity profile by a sine wave perturbation. Two types of wall-jet simulations are carried out, a two-dimensional compressible case at Rein = 5000 using the PyFR solver and a three-dimensional incompressible case at Rein = 6000 using the Nek5000 solver. The compressible wall-jet simulation indicates that the addition of a sine wave perturbation of 1% on the inlet velocity, at the initial shear layer, increases the wall-normal turbulence intensity at a Strouhal number (Sr) of 0.05 and reduces the turbulence intensity in all directions at a Sr of 0.25. The incompressible wall-jet simulations show that a perturbation of magnitude 40% of the inlet velocity at a low Sr number of 0.0048 damps turbulence and leads to skin friction reduction. The forced wall-jet experiences a repetitive re-laminarization process that delays transition as well as separation from the wall. A qualitative parametric analysis of the perturbation of the global behavior of the flow development on a plane wall-jet under forced velocity profiles is also presented. Cases at Sr = 0.0048 experience a reduction in the number of turbulent structures while becoming more stable, indicating potential drag reduction. Cases at Sr = 0.02 experience a frequent energy re-supply from the inlet that helps maintain large turbulent structures at further downstream locations, useful for mixing related applications."--Abstract.
Manipulation And Control Of Jets In Crossflow
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Author : Ann R. Karagozian
language : en
Publisher: Springer
Release Date : 2014-05-04
Manipulation And Control Of Jets In Crossflow written by Ann R. Karagozian and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-05-04 with Technology & Engineering categories.
Fundamental Non-Reactive Jets in Crossflow and Other Jet Systems; Background on Modeling, Dynamical Systems, and Control; Reactive Jets in Crossflow and Multiphase Jets; Controlled Jets in Crossflow and Control via Jet Systems;
An Experimental Investigation Of A Non Isothermal Turbulent Wall Jet
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Author : Jack Duane Wilson
language : en
Publisher:
Release Date : 1968
An Experimental Investigation Of A Non Isothermal Turbulent Wall Jet written by Jack Duane Wilson and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1968 with Air ducts categories.
Steady And Pulsating Two Dimensional Turbulent Wall Jets In A Uniform Stream
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Author : August Verhoff
language : en
Publisher:
Release Date : 1970
Steady And Pulsating Two Dimensional Turbulent Wall Jets In A Uniform Stream written by August Verhoff and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1970 with Jets categories.
For the case of the steady, plane turbulent wall jet, the growth of the jet and decay of maximum velocity are predicted based upon the assumption that the shear stress distribution as well as the velocity distribution across the jet remain similar over the useful range of downstream positions. A suggested form for the velocity distribution is compared with the experimental results of this investigation and with the results of several previous investigators. The approach used in the analysis of the plane turbulent wall jet is then extended to the more general case of a steady turbulent wall jet beneath a secondary uniform stream. The experimental results of this investigation and other previous investigations are compared with the velocity profiles as predicted by the analysis. The case of a pulsating wall jet flow field was also analyzed; a simplified theoretical model is presented based upon the experimentally observed discrete vortex pattern produced by the unsteady jet. The analysis for both zero and nonzero secondary flow velocity relies to a large extent on many of the results of potential flow theory and the known characteristics of turbulent vortex structure. Experimental data consisting of instantaneous velocity measurements obtained by means of a hot-wire anemometer system and information obtained from visual flow field studies are compared with the results of the theoretical analysis. (Author).
Injection And Mixing In Turbulent Flow
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Author : Joseph A. Schetz
language : en
Publisher:
Release Date : 1980
Injection And Mixing In Turbulent Flow written by Joseph A. Schetz and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1980 with Science categories.
Good,No Highlights,No Markup,all pages are intact, Slight Shelfwear,may have the corners slightly dented, may have slight color changes/slightly damaged spine.
Analysis Of An Axisymmetrical Turbulent Pulsating Jet
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Author : D. Olivari
language : en
Publisher:
Release Date : 1974
Analysis Of An Axisymmetrical Turbulent Pulsating Jet written by D. Olivari and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1974 with Jets categories.
An Experimental Investigation Of Ducted Reactive Turbulent Jet Mixing With Recirculation
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Author : D. E. Chriss
language : en
Publisher:
Release Date : 1977
An Experimental Investigation Of Ducted Reactive Turbulent Jet Mixing With Recirculation written by D. E. Chriss and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1977 with Gas flow categories.
An experimental investigation of ducted, two stream, subsonic, reactive, turbulent jet mixing with recirculation was conducted. A primary jet of air at a mass flow rate of 0.075 lb/sec and velocity of 700 ft/sec was surrounded by an outer, low velocity, hydrogen stream. Data were obtained with hydrogen-air ratios of 0.143 and 0.107. The duct-to-inner nozzle diameter ratio was ten. Radial distributions of hydrogen mass fraction, mean axial velocity, turbulence intensity, and total pressure as well as axial distributions of wall hydrogen mass fraction and wall static pressure are presented for axial stations from one-half to five duct diameters from the nozzle exit plane. Comparison of the experimental data with calculations assuming frozen or equilibrium chemistry indicate that he measured velocity, pressure, and composition data are, in general, self-consistent. The maximum turbulent intensities which occurred in the center of the mixing layer and within the recirculation eddy were very high having values of 20 percent of the jet exit velocity. The velocity and composition field indicate that, while and mixing in the reactive flow field is slower than for the nonreactive case, the reaction had little effect on the size and location of the recirculation zone within the mixing duct.
Large Eddy Simulation Of Heated Pulsed Jets In High Speed Turbulent Crossflow
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Author : Venkata-Ramya Pasumarti
language : en
Publisher:
Release Date : 2010
Large Eddy Simulation Of Heated Pulsed Jets In High Speed Turbulent Crossflow written by Venkata-Ramya Pasumarti and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with Eddies categories.
The jet-in-crossflow problem has been extensively studied, mainly because of its applications in film cooling and injector designs. It has been established that in low-speed flows, pulsing the jet significantly enhances mixing and jet penetration.: This work investigates the effects of pulsing on mixing and jet trajectory in high speed (compressible) flow, using Large Eddy Simulation. Jets with different density ratios, velocity ratios and momentum ratios are pulsed from an injector into a crossflow.
The Turbulent Wall Jet
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Author :
language : en
Publisher:
Release Date : 1993
The Turbulent Wall Jet written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with categories.
The flow of a wall jet embedded in an external stream or in a quiescent surrounding fluid was investigated experimentally. It was determined that the flow scales with the excess momentum injected into the stream and the viscosity of the fluid rather than the jet efflux velocity and the dimension of the nozzle. In the presence of an external stream, a velocity ratio parameter R = (U i - U.)/(Uj + U) had to be added in order to obtain a universal scaling of this flow. Low-amplitude external excitation, of the wall jet resulted in a reduction of skin friction and therefore a reduction of drag. The only possible cause for this behavior observed is the enhancement of the two-dimensionality of the large eddies as expressed by spanwise coherence and correlation measurements ... Turbulence, Control of Shear Flows, Wall Jet, Boundary Layer Control.
Scientific And Technical Aerospace Reports
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Author :
language : en
Publisher:
Release Date : 1995
Scientific And Technical Aerospace Reports written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with Aeronautics categories.
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.