An Overview of Computational Aeroacoustic Techniques Applied to Cavity Noise Prediction PDF Download
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Author: Sheryl M. Grace
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Languages : en
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Author: Sheryl M. Grace
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Languages : en
Pages :
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Author: Jay C. Hardin
Publisher: Springer Science & Business Media
ISBN: 1461383420
Category : Science
Languages : en
Pages : 525
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Book Description
Computational aeroacoustics is rapidly emerging as an essential element in the study of aerodynamic sound. As with all emerging technologies, it is paramount that we assess the various opportuni ties and establish achievable goals for this new technology. Essential to this process is the identification and prioritization of fundamental aeroacoustics problems which are amenable to direct numerical siIn ulation. Questions, ranging from the role numerical methods play in the classical theoretical approaches to aeroacoustics, to the correct specification of well-posed numerical problems, need to be answered. These issues provided the impetus for the Workshop on Computa tional Aeroacoustics sponsored by ICASE and the Acoustics Division of NASA LaRC on April 6-9, 1992. The participants of the Work shop were leading aeroacousticians, computational fluid dynamicists and applied mathematicians. The Workshop started with the open ing remarks by M. Y. Hussaini and the welcome address by Kristin Hessenius who introduced the keynote speaker, Sir James Lighthill. The keynote address set the stage for the Workshop. It was both an authoritative and up-to-date discussion of the state-of-the-art in aeroacoustics. The presentations at the Workshop were divided into five sessions - i) Classical Theoretical Approaches (William Zorumski, Chairman), ii) Mathematical Aspects of Acoustics (Rodolfo Rosales, Chairman), iii) Validation Methodology (Allan Pierce, Chairman), iv) Direct Numerical Simulation (Michael Myers, Chairman), and v) Unsteady Compressible Flow Computa tional Methods (Douglas Dwoyer, Chairman).
Author: Steffen Marburg
Publisher: Springer Science & Business Media
ISBN: 3540774483
Category : Science
Languages : en
Pages : 584
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The book provides a survey of numerical methods for acoustics, namely the finite element method (FEM) and the boundary element method (BEM). It is the first book summarizing FEM and BEM (and optimization) for acoustics. The book shows that both methods can be effectively used for many other cases, FEM even for open domains and BEM for closed ones. Emphasis of the book is put on numerical aspects and on treatment of the exterior problem in acoustics, i.e. noise radiation.
Author: Konstantinos Kontis
Publisher: Springer Science & Business Media
ISBN: 3642256856
Category : Science
Languages : en
Pages : 1122
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The University of Manchester hosted the 28th International Symposium on Shock Waves between 17 and 22 July 2011. The International Symposium on Shock Waves first took place in 1957 in Boston and has since become an internationally acclaimed series of meetings for the wider Shock Wave Community. The ISSW28 focused on the following areas: Blast Waves, Chemically Reacting Flows, Dense Gases and Rarefied Flows, Detonation and Combustion, Diagnostics, Facilities, Flow Visualisation, Hypersonic Flow, Ignition, Impact and Compaction, Multiphase Flow, Nozzle Flow, Numerical Methods, Propulsion, Richtmyer-Meshkov, Shockwave Boundary Layer Interaction, Shock Propagation and Reflection, Shock Vortex Interaction, Shockwave Phenomena and Applications, as well as Medical and Biological Applications. The two Volumes contain the papers presented at the symposium and serve as a reference for the participants of the ISSW 28 and individuals interested in these fields.
Author: N. Sarigul-Klijn
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Category :
Languages : en
Pages :
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Author: Douglas William Dietz
Publisher:
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Category :
Languages : en
Pages : 170
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Category : Aeronautics
Languages : en
Pages : 724
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Author: M. Rahman
Publisher: WIT Press
ISBN: 1845641094
Category : Science
Languages : en
Pages : 513
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Covering the latest developments in this field, this text features edited versions of papers presented at the Seventh International Conference on Advances in Fluid Mechanics.
Author: Brent Paul
Publisher:
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Category :
Languages : en
Pages :
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The hydrodynamically generated noise produced from flow over cavities includes both broadband and tones. The frequency content and amplitude of the resulting noise is a function of the cavity geometry and the approaching boundary layer. The cavity length to depth ratio (L/D) is an important parameter that governs the characteristics of cavity noise generated. While both of the noise components are important this work will focus on the production of cavity tones. Cavity tones typically have higher sound pressure levels and can propagate over longer distances than the broadband noise.The enhancements to the numerical code shown in this work result in the first non-hybrid tool for the prediction of low speed cavity noise. At moderate subsonic Mach numbers the direct calculation of cavity tones has been performed by numerous researchers using highly accurate spatial and time discretization. However, most researchers that are trying to predict the noise from low Mach number flows take a hybrid approach where the fluid dynamics of the simulation are solved with a computational fluid dynamics (CFD) solver and the acoustics are solved separately. The other solver is often based on Lighthills Acoustic Analogy or an asympototic method such as the Expansion about Incompressible Flow (EIF). This work calculates the conservative Navier-Stokes variables to directly predict the cavity tones.The numerical solver CHOPA (Compressible, High-Order Parallel Acoustics) is extended in this work for the accurate and fast calculation of low Mach number cavity flows. A time-derivative preconditioner equalizes the acoustic wave and turbulence convective speeds to allow for a more efficient time step and shorter calculation times. Because the preconditioner destroys the time accuracy of the solution a dual-time step approach is used for the time integration. Other modifications to the code are required to facilitate the proper implementation of the preconditioner: Matrix-based artificial dissipation, buffer zone, and extrapolation boundary condition. An extension by Buelow of Choi-Merkles viscous preconditioner is selected for this work.There are several different numerical validations performed on the preconditioned Navier-Stokes solver to ensure high quality solutions. First, the combination buffer zone/extrapolation boundary condition is tested by simulating the propagation of a Gaussian pressure pulse. Then the preconditioner is tested with several different analyses. The convection of a uniform velocity flow field with a random perturbation imposed on the flow field tests if the preconditioned solution is independent of the flow Mach number. Then a time accurate Gaussian pressure pulse tests the ability of the preconditioner to solve a time dependent solution. Lastly, a laminar boundary layer flow is calculated and compared to an exact solution showing that the preconditioner is effective for viscous flows. The prediction of cavity tones from a deep (L/D = 0.78) and shallow (L/D = 2.35) cavity is simulated for comparison against the experimental measurements of Block. The Mach number of the simulations varied from 0.05 to 0.4. The cavity tone frequencies have an acceptable comparison against the measurements for the deep cavity. However, the shallow cavity tones were almost independent of the flow speed, which may be an indication that standing waves in the cavity could be responsible for the tones for this geometry. The other cavity simulations replicated the experiment by Stallings et al.for L/D = 5.42 and L/D = 6.25 for a Mach number of 0.2. The time-averaged wall pressure fluctuations were compared to measurements. While the predicted wall pressures did not match the experiment the discrepancy is because of the existence of a wake mode in the numerical results. This is a two-dimensional phenomenon where a large vortex is generated in the cavity and then violently ejected from the cavity, significantly increasing drag. While not matching the experiment the results behave as expected for a cavity resonating in a wake mode.
Author: Shia-Hui Peng
Publisher: Springer Science & Business Media
ISBN: 3540778152
Category : Technology & Engineering
Languages : en
Pages : 343
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Turbulence modelling has long been, and will remain, one of the most important t- ics in turbulence research, challenging scientists and engineers in the academic world and in the industrial society. Over the past decade, Detached Eddy Simulation (DES) and other hybrid RANS-LES methods have received increasing attention from the turbulence-research community, as well as from industrial CFD engineers. Indeed, as an engineering modelling approach, hybrid RANS-LES methods have acquired a remarkable profile in modelling turbulent flows of industrial interest in relation to, for example, transportation, energy production and the environment. The advantage exploited with hybrid RANS-LES modelling approaches, being - tentially more computationally efficient than LES and more accurate than (unsteady) RANS, has motivated numerous research and development activities. These activities, together with industrial applications, have been further facilitated over the recent years by the rapid development of modern computing resources. As a European initiative, the EU project DESider (Detached Eddy Simulation for Industrial Aerodynamics, 2004-2007), has been one of the earliest and most systematic international R&D effort with its focus on development, improvement and applications of a variety of existing and new hybrid RANS-LES modelling approaches, as well as on related numerical issues. In association with the DESider project, two subsequent international symposia on hybrid RANS-LES methods have been arranged in Stockholm (Sweden, 2005) and in Corfu (Greece, 2007), respectively. The present book is a result of the Second Symposium on Hybrid RANS-LES Methods, held in Corfu, Greece, 17-18 June 2007.
