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Effect Of Swirl On Turbulent Structures In Supersonic Jets
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Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722192457 Total Pages :36 pages Book Rating :4.1/5 (924 download)
Book Synopsis Effect of Swirl on Turbulent Structures in Supersonic Jets by : National Aeronautics and Space Administration (NASA)
Download or read book Effect of Swirl on Turbulent Structures in Supersonic Jets written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-02 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Direct Numerical Simulation (DNS) is used to study the mechanism of generation and evolution of turbulence structures in a temporally evolving supersonic swirling round jet and also to examine the resulting acoustic radiations. Fourier spectral expansions are used in the streamwise and azimuthal directions and a 1-D b-spline Galerkin representation is used in the radial direction. Spectral-like accuracy is achieved using this numerical scheme. Direct numerical simulations, using the b-spline spectral method, are carried out starting from mean flow initial conditions which are perturbed by the most unstable linear stability eigenfunctions. It is observed that the initial helical instability waves evolve into helical vortices which eventually breakdown into smaller scales of turbulence. 'Rib' structures similar to those seen in incompressible mixing layer flow of Rogers and Moserl are observed. The jet core breakdown stage exhibits increased acoustic radiations. Rao, Ram Mohan and Lundgren, Thomas S. Ames Research Center NCC2-5221...
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722333546 Total Pages :34 pages Book Rating :4.3/5 (335 download)
Book Synopsis Large Scale Turbulent Structures in Supersonic Jets by : National Aeronautics and Space Administration (NASA)
Download or read book Large Scale Turbulent Structures in Supersonic Jets written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-05 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Jet noise is a major concern in the design of commercial aircraft. Studies by various researchers suggest that aerodynamic noise is a major contributor to jet noise. Some of these studies indicate that most of the aerodynamic jet noise due to turbulent mixing occurs when there is a rapid variation in turbulent structure, i.e. rapidly growing or decaying vortices. The objective of this research was to simulate a compressible round jet to study the non-linear evolution of vortices and the resulting acoustic radiations. In particular, to understand the effect of turbulence structure on the noise. An ideal technique to study this problem is Direct Numerical Simulations (DNS), because it provides precise control on the initial and boundary conditions that lead to the turbulent structures studied. It also provides complete 3-dimensional time dependent data. Since the dynamics of a temporally evolving jet are not greatly different from those of a spatially evolving jet, a temporal jet problem was solved, using periodicity in the direction of the jet axis. This enables the application of Fourier spectral methods in the streamwise direction. Physically this means that turbulent structures in the jet are repeated in successive downstream cells instead of being gradually modified downstream into a jet plume. The DNS jet simulation helps us understand the various turbulent scales and mechanisms of turbulence generation in the evolution of a compressible round jet. These accurate flow solutions will be used in future research to estimate near-field acoustic radiation by computing the total outward flux across a surface and determine how it is related to the evolution of the turbulent solutions. Furthermore, these simulations allow us to investigate the sensitivity of acoustic radiations to inlet/boundary conditions, with possible appli(, a- tion to active noise suppression. In addition, the data generated can be used to compute, various turbulence quantities such as mean velociti..
Book Synopsis Evolution of Large-scale Turbulent Structures in Coannular Supersonic Jets by : Erina Murakami
Download or read book Evolution of Large-scale Turbulent Structures in Coannular Supersonic Jets written by Erina Murakami and published by . This book was released on 1998 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Turbulent Shear Layers in Supersonic Flow by : Alexander J. Smits
Download or read book Turbulent Shear Layers in Supersonic Flow written by Alexander J. Smits and published by Springer Science & Business Media. This book was released on 2006-05-11 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Multiscale Turbulence Effects in Supersonic Jets Exhausting Into Still Air by : Khaled Sayed Abdol-Hamid
Download or read book Multiscale Turbulence Effects in Supersonic Jets Exhausting Into Still Air written by Khaled Sayed Abdol-Hamid and published by . This book was released on 1987 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Multiscale Turbulence Effects in Supersonic Jets Exhausting Into Still Air by : Khaled S. Abdol-Hamid
Download or read book Multiscale Turbulence Effects in Supersonic Jets Exhausting Into Still Air written by Khaled S. Abdol-Hamid and published by . This book was released on 1987 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Supersonic Jet Exhaust Noise Investigation. Volume II. Technical Report by : Paul R. Knott
Download or read book Supersonic Jet Exhaust Noise Investigation. Volume II. Technical Report written by Paul R. Knott and published by . This book was released on 1976 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report discusses detailed accounts of major theoretical and experimental investigations directed toward obtaining better understanding and mathematical specification of supersonic turbulent jets. Complete theoretical discussions are given describing the influence of a jet's mean flow shrouding on acoustic radiation of heated and unheated jets, approximate closed form acoustic expressions for turbulent mixing noise characterized by self-noise and shear-noise are given, and theoretical aero-acoustic formulations for the orderly structure of supersonic jets are reviewed. Extensive theory/data comparisons of developed acoustic models are given. Experimental investigations aimed at studying high velocity jet refraction, and the influence of jet swirl and upstream combustion roughness on jet noise is presented. Additionally, an extensive series of laser velocimeter measurements for high velocity and high temperature simple circular jets is discussed. Results include hot-film/laser velocimeter comparisons for ambient jets, mean velocity and turbulent velocity plume surveys of heated supersonic shock-free and shocked flow nozzles, and a demonstration experiment illustrating the capability of performing in-jet turbulence to far-field acoustic cross-correlation. (Author).
Book Synopsis Direct Numerical Simulation of Turbulent Supersonic Jets by : Ram Mohan Rao
Download or read book Direct Numerical Simulation of Turbulent Supersonic Jets written by Ram Mohan Rao and published by . This book was released on 1997 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Effects of Expansion Regions on the Turbulence Structure of a Supersonic Boundary Layer by :
Download or read book The Effects of Expansion Regions on the Turbulence Structure of a Supersonic Boundary Layer written by and published by . This book was released on 1996 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: A fully-developed high Reynolds number Mach 3 turbulent boundary layer and the effects of four expansion regions (centered and gradual expansions of 7 deg and 14 deg) on the boundary layer were investigated by utilizing 1) multi-point instantaneous surface pressure measurements, 2) instantaneous single- and double-pulse flow visualizations based on Filtered Rayleigh Scattering (FRS), 3) two-component planar velocity measurements using Filtered Planar Velocimetry (FPV), and 4) detailed turbulence measurements using Laser Doppler Velocimetry (LDV). Flow visualization results indicate that the upper half of the fully developed turbulent boundary layer is populated with elongated longitudinal structures of considerable streamwise but very limited spanwise extent. These structures are randomly distributed in space and time and survive even the 14 deg centered expansion. The visualizations also show that large scale structures increase both in size and angle and small scale structures are quenched across the expansions. The angle of large scale structures return to the flat plate value further downstream of the expansions. The normalized power spectra of pressure fluctuations downstream of the expansions are more concentrated at lower frequencies than their upstream counterparts, confirming the small scale quenching shown by flow visualizations.
Book Synopsis Fundamental Aspects of the Structure of Supersonic Turbulent Boundary Layers by : Alexander J. Smits
Download or read book Fundamental Aspects of the Structure of Supersonic Turbulent Boundary Layers written by Alexander J. Smits and published by . This book was released on 1988 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Turbulence and Interactions by : Michel Deville
Download or read book Turbulence and Interactions written by Michel Deville and published by Springer. This book was released on 2014-10-15 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keynote Lectures.- Some Characteristics of Non-Reacting and Reacting Low Swirl Number Jets.- Inner-Outer Interactions in Wall-Bounded Turbulence.- Turbulence Interaction with Atmospheric Physical Processes.- LES of Pulsating Turbulent Flows over Smooth and Wavy Boundaries.- Numerical Study of Turbulence-Wave Interaction.- High Reynolds Number Wall-Bounded Turbulence and a Proposal for a New Eddy-Based Model.- Regular Papers.- PANS Methodology Applied to Elliptic-Relaxation Based Eddy Viscosity Transport Model.- PIV Study of Turbulent Flow in Porous Media.- A Model for Dissipation: Cascade SDE with Markov Regime-Switching and Dirichlet Prior.- Wavelet Analysis of the Turbulent LES Data of the Lid-Driven Cavity Flow.- A Two-Phase LES Compressible Model for Plasma-Liquid Jet Interaction.- Simulation of a Fluidized Bed Using a Hybrid Eulerian-Lagrangian Method for Particle Tracking.- Wavelet-Adapted Sub-grid Scale Models for LES.- Effect of Particle-Particle Collisions on the Spatial Distribution of Inertial Particles Suspended in Homogeneous Isotropic Turbulent Flows.- Effect of Near-Wall Componental Modification of Turbulence on Its Statistical Properties.- Large-Eddy Simulation of Transonic Buffet over a Supercritical Airfoil.- Large Eddy Simulation of Coherent Structures over Forest Canopy.- Toroidal/Poloidal Modes Dynamics in Anisotropic Turbulence.- Grid Filter Modeling for Large-Eddy Simulation.- Pulsating Flow through Porous Media.- Thermodynamic Fluctuations Behaviour during a Sheared Turbulence/Shock Interaction.- LES and DES Study of Fluid-Particle Dynamics in a Human Mouth-Throat Geometry.- Viscous Drag Reduction with Surface-Embedded Grooves.- Study on the Resolution Requirements for DNS in Turbulent Rayleigh-Bénard Convection.- On the Role of Coherent Structures in a Lid Driven Cavity Flow.- Local versus Nonlocal Processes in Turbulent Flows, Kinematic Coupling and General Stochastic Processes.- Time-Resolved 3D Simulation of an Aircraft Wing with Deployed High-Lift System.- Fluid Mechanics and Heat Transfer in a Channel with Spherical and Oval Dimples.- Investigation of the Flow around a Cylinder Plate Configuration with Respect to Aerodynamic Noise Generation Mechanisms.- LES of the Flow around Ahmed Body with Active Flow Control.- Enhanced Bubble Migration in Turbulent Channel Flow by an Acceleration-Dependent Drag Coefficient.- Experimental and Numerical Study of Unsteadiness in Boundary Layer / Shock Wave Interaction.- Measurement of Particle Accelerations with the Laser Doppler Technique.- A Novel Numerical Method for Turbulent, Two-Phase Flow.- Modeling of High Reynolds Number Flows with Solid Body Rotation or Magnetic Fields.- Direct Numerical Simulation of Buoyancy Driven Turbulence inside a Cubic Cavity.- Numerical Simulations of a Massively Separated Reactive Flow Using a DDES Approach for Turbulence Modelling.- Particle Dispersion in Large-Eddy Simulations: Influence of Reynolds Number and of Subgrid Velocity Deconvolution.- Use of Lagrangian Statistics for the Direct Analysis of the Turbulent Constitutive Equation.- Numerical Simulation of Supersonic Jet Noise with Overset Grid Techniques.- Large Eddy Simulation of Turbulent Jet Flow in Gas Turbine Combustors.- Computations of the Flow around a Wind Turbine: Grid Sensitivity Study and the Influence of Inlet Conditions.- Stochastic Synchronization of the Wall Turbulence.- Large-Eddy Simulations of an Oblique Shock Impinging on a Turbulent Boundary Layer: Effect of the Spanwise Confinement on the Low-Frequency Oscillations.- Parameter-Free Symmetry-Preserving Regularization Modelling of Turbulent Natural Convection Flows.- An a Priori Study for the Modeling of Subgrid Terms in Multiphase Flows.- Computation of Flow in a 3D Diffuser Using a Two-Velocity Field Hybrid RANS/LES.- On the Dynamics of High Reynolds Number Turbulent Axisymmetric and Plane Separating/Reattaching Flows.- Numerical Simulation and Statistical Modeling of Inertial Droplet Coalescence
Book Synopsis High Resolution Measurements of Supersonic Mixing and Combustion in Coflowing Turbulent Jets by :
Download or read book High Resolution Measurements of Supersonic Mixing and Combustion in Coflowing Turbulent Jets written by and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study of compressibility effects on the large scale structure and outer variable scaling laws of a coflowing turbulent jet was partially completed. Results showed distinct large scale structure and classical incompressible scaling where the convective Mach number has decreased to subsonic values. At supersonic convective Mach numbers no large scale structure was seen and incompressible scalings were dramatically modified. Experiments also showed strong effects due to oblique shock wave interactions with combustion in supersonic turbulent jets. OH PLIF imaging measurements comparing subsonic and supersonic jets documented striking differences in their mixing and combustion properties. Combined OH/CH PLIF imaging measurements found large differences in the combustion properties of jet flames created by small differences in the fuel injection design. A theoretical study of density effects due to combustion heat release on the outer variable scalings of turbulent shear flows was completed. This study produced a general methodology for predicting the changes in such quantities as growth rates, velocity decay, and entrainment and mixing rates due to heat release. Comparisons with measured heat release effects in the literature, including planar and axisymmetric jet flames as well as mixing layers, showed excellent agreement with this general approach.
Book Synopsis Mixing, Chemical Reactions, and Combustion in Subsonic and Supersonic Turbulent Flows by :
Download or read book Mixing, Chemical Reactions, and Combustion in Subsonic and Supersonic Turbulent Flows written by and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Work completed, or in progress, by the end of the first grant year includes a study of the effects of initial conditions on high Reynolds number shear layers, where it was shown that they also influence molecular mixing far downstream of the splitter plate; moderate Reynolds number, liquid-phase transverse jets in a cross flow, including their three-dimensional structure; the discovery of a power-law similarity in the surface-to root-area ratio of scalar structures in liquid-phase turbulent jets; numerical investigations of hydrocarbon ignition and the effects of additives in a high-strain rate environment, as would be encountered in air-breathing scramjet propulsion; and further advances and applications of velocity-field measurements from image sequences of convected scalars.
Download or read book Air Force Research Resumés written by and published by . This book was released on with total page 854 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Research and Technology Program Digest by : United States. National Aeronautics and Space Administration
Download or read book Research and Technology Program Digest written by United States. National Aeronautics and Space Administration and published by . This book was released on with total page 792 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aeronautical Engineering written by and published by . This book was released on 1991 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt:
