Download or read book Aeroacoustic Computation of Tones Generated from Low Mach Number Cavity Flows Using a Preconditioned Method written by Brent Paul and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Computational Aeroacoustics in Low Mach Number Flows written by Pradera-Mallabiabarrena Ainara and published by LAP Lambert Academic Publishing. This book was released on 2015-08-10 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work studies a flexible methodology to predict radiated noise. The main contributions of this work are focused on the way flow parameters are acquired in fluid dynamics simulations are synthesised, stored and later used to predict radiated noise, but also on the procedure considered in the radiation calculations. The methodology has been restricted to low Mach number flows where the noise generation is dominated by the interaction of the flow with a surface at least one of whose typical dimensions is short compared to the wavelength of intereset, known as a compact source. The radiation calculations may employ purely analytical methods or numerical methods, depending on the application. Finally, the requirements in data storage and transfer are significantly reduced by using this method. Besides, if the flow remains essentially the same, the Computational Fluid Dynamics simulation should not need to be repeated in case different acoustic scenarios should be studied.
Download or read book Aeroacoustic Computation of Low Mach Number Flow written by Kristian Skriver Dahl and published by . This book was released on 1996 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aerospace America written by and published by . This book was released on 2004 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Aeroacoustic Computation of Subsonic Flows written by Scot Andrew Slimon and published by . This book was released on 1999 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Investigation of Aeroacoustic Interaction in the Turbulent Subsonic Fow Past an Open Cavity written by Thangasivam Gandhi and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this thesis is to study numerically the aeroacoustics of low Mach number (M inf 0.3) fow with thick turbulent boundary layer past a cavity based on Large Eddy Simulation (LES). Velocity profiles from power law and equilibrium turbulent boundary layer were imposed as inlet conditions on the computational domain. The equilibrium turbulent boundary layer profles (zero and adverse pressure gradient) have been generated using a symptotic approach with an improved mixing length model. A good agreement is observed between the computed boundary layer profiles and the profiles obtained from experiments and direct numerical simulations. LES results present the infuence of the thickness of the incoming turbulent boundary layers on the mode of oscillation in the shallow cavity of L/D=4. An agreement with the experiments of Haigermoser and the shear mode have been found for the upstream velocity 5.8m/s. Wake mode was observed for the other two test cases at 20 and 40m/s. A 3D cavity simulation is performed to show that the wake mode observed in the 2D calculations is an artifact. The hydrodynamic pressure feld obtained from the 2D simulation is used as an input to the acoustic analogy (Lighthill-Curle's analogy), to compute the acoustic pressure feld at the near and far feld of the cavities. Conforming the experiments of Haigermoser, a weak directivity of sound propagation was observed. Shear mode infuences the sound pressure levels strongly.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1016 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unsteady Aerodynamics Aeroacoustics and Aeroelasticity of Turbomachines written by Kenneth C. Hall and published by Springer Science & Business Media. This book was released on 2006-05-11 with total page 605 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook is a collection of technical papers that were presented at the 10th International Symposium on Unsteady Aerodynamics, Aeroacoustics, and Aeroelasticity of Turbomachines held September 8-11, 2003 at Duke University in Durham, North Carolina. The papers represent the latest in state of the art research in the areas of aeroacoustics, aerothermodynamics, computational methods, experimental testing related to flow instabilities, flutter, forced response, multistage, and rotor-stator effects for turbomachinery.
Download or read book Aeroacoustic Measurements written by Thomas J. Mueller and published by Springer Science & Business Media. This book was released on 2013-11-27 with total page 327 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book describes recent developments in aeroacoustic measurements in wind tunnels and the interpretation of the resulting data. The reader will find the latest measurement techniques described along with examples of the results.
Download or read book Shock Wave Boundary Layer Interactions written by Holger Babinsky and published by Cambridge University Press. This book was released on 2011-09-12 with total page 481 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shock wave-boundary-layer interaction (SBLI) is a fundamental phenomenon in gas dynamics that is observed in many practical situations, ranging from transonic aircraft wings to hypersonic vehicles and engines. SBLIs have the potential to pose serious problems in a flowfield; hence they often prove to be a critical - or even design limiting - issue for many aerospace applications. This is the first book devoted solely to a comprehensive, state-of-the-art explanation of this phenomenon. It includes a description of the basic fluid mechanics of SBLIs plus contributions from leading international experts who share their insight into their physics and the impact they have in practical flow situations. This book is for practitioners and graduate students in aerodynamics who wish to familiarize themselves with all aspects of SBLI flows. It is a valuable resource for specialists because it compiles experimental, computational and theoretical knowledge in one place.
Download or read book Unsteady Computational Fluid Dynamics in Aeronautics written by P.G. Tucker and published by Springer Science & Business Media. This book was released on 2013-08-30 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of Large Eddy Simulation (LES) and hybrids is a vibrant research area. This book runs through all the potential unsteady modelling fidelity ranges, from low-order to LES. The latter is probably the highest fidelity for practical aerospace systems modelling. Cutting edge new frontiers are defined. One example of a pressing environmental concern is noise. For the accurate prediction of this, unsteady modelling is needed. Hence computational aeroacoustics is explored. It is also emerging that there is a critical need for coupled simulations. Hence, this area is also considered and the tensions of utilizing such simulations with the already expensive LES. This work has relevance to the general field of CFD and LES and to a wide variety of non-aerospace aerodynamic systems (e.g. cars, submarines, ships, electronics, buildings). Topics treated include unsteady flow techniques; LES and hybrids; general numerical methods; computational aeroacoustics; computational aeroelasticity; coupled simulations and turbulence and its modelling (LES, RANS, transition, VLES, URANS). The volume concludes by pointing forward to future horizons and in particular the industrial use of LES. The writing style is accessible and useful to both academics and industrial practitioners. From the reviews: "Tucker's volume provides a very welcome, concise discussion of current capabilities for simulating and modellng unsteady aerodynamic flows. It covers the various pos sible numerical techniques in good, clear detail and presents a very wide range of practical applications; beautifully illustrated in many cases. This book thus provides a valuable text for practicing engineers, a rich source of background information for students and those new to this area of Research & Development, and an excellent state-of-the-art review for others. A great achievement." Mark Savill FHEA, FRAeS, C.Eng, Professor of Computational Aerodynamics Design & Head of Power & Propulsion Sciences, Department of Power & Propulsion, School of Engineering, Cranfield University, Bedfordshire, U.K. "This is a very useful book with a wide coverage of many aspects in unsteady aerodynamics method development and applications for internal and external flows." L. He, Rolls-Royce/RAEng Chair of Computational Aerothermal Engineering, Oxford University, U.K. "This comprehensive book ranges from classical concepts in both numerical methods and turbulence modelling approaches for the beginner to latest state-of-the-art for the advanced practitioner and constitutes an extremely valuable contribution to the specific Computational Fluid Dynamics literature in Aeronautics. Student and expert alike will benefit greatly by reading it from cover to cover." Sébastien Deck, Onera, Meudon, France
Download or read book High Performance Computing in Science and Engineering 18 written by Wolfgang E. Nagel and published by Springer. This book was released on 2019-06-07 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the state-of-the-art in supercomputer simulation. It includes the latest findings from leading researchers using systems from the High Performance Computing Center Stuttgart (HLRS) in 2018. The reports cover all fields of computational science and engineering ranging from CFD to computational physics and from chemistry to computer science with a special emphasis on industrially relevant applications. Presenting findings of one of Europe’s leading systems, this volume covers a wide variety of applications that deliver a high level of sustained performance. The book covers the main methods in high-performance computing. Its outstanding results in achieving the best performance for production codes are of particular interest for both scientists and engineers. The book comes with a wealth of color illustrations and tables of results.
Download or read book Acoustic Analyses Using Matlab and Ansys written by Carl Q. Howard and published by CRC Press. This book was released on 2014-12-18 with total page 711 pages. Available in PDF, EPUB and Kindle. Book excerpt: Techniques and Tools for Solving Acoustics Problems This is the first book of its kind that describes the use of ANSYS® finite element analysis (FEA) software, and MATLAB® engineering programming software to solve acoustic problems. It covers simple text book problems, such as determining the natural frequencies of a duct, to progressively more complex problems that can only be solved using FEA software, such as acoustic absorption and fluid-structure-interaction. It also presents benchmark cases that can be used as starting points for analysis. There are practical hints too for using ANSYS software. The material describes how to solve numerous problems theoretically, and how to obtain solutions from the theory using MATLAB engineering software, as well as analyzing the same problem using ANSYS Workbench and ANSYS Mechanical APDL. Developed for the Practicing Engineer Free downloads on http://www.mecheng.adelaide.edu.au/avc/software, including MATLAB source code, ANSYS APDL models, and ANSYS Workbench models Includes readers’ techniques and tips for new and experienced users of ANSYS software Identifies bugs and deficiencies to help practitioners avoid making mistakes Acoustic Analyses Using MATLAB® and ANSYS® can be used as a textbook for graduate students in acoustics, vibration, and related areas in engineering; undergraduates in mechanical and electrical engineering; and as an authoritative reference for industry professionals.
Download or read book Design and Development of Aerospace Vehicles and Propulsion Systems written by S. Kishore Kumar and published by Springer Nature. This book was released on 2021-03-18 with total page 529 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents selected papers presented in the Symposium on Applied Aerodynamics and Design of Aerospace Vehicles (SAROD 2018), which was jointly organized by Aeronautical Development Agency (the nodal agency for the design and development of combat aircraft in India), Gas-Turbine Research Establishment (responsible for design and development of gas turbine engines for military applications), and CSIR-National Aerospace Laboratories (involved in major aerospace programs in the country such as SARAS program, LCA, Space Launch Vehicles, Missiles and UAVs). It brings together experiences of aerodynamicists in India as well as abroad in Aerospace Vehicle Design, Gas Turbine Engines, Missiles and related areas. It is a useful volume for researchers, professionals and students interested in diversified areas of aerospace engineering.
Download or read book IUTAM Symposium on Unsteady Separated Flows and their Control written by Marianna Braza and published by Springer Science & Business Media. This book was released on 2009-09-29 with total page 588 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Volume is the Proceedings of the IUTAM Symposium on Unsteady Separated Flows and Their Control held in Corfu, Greece, 18–22 June 2007. This was the second IUTAM Symposium on this subject, following the symposium in Toulouse, in April 2002. The Symposium consisted of single plenary sessions with invited lectures, - lected oral presentations, discussions on special topics and posters. The complete set of papers was provided to all participants at the meeting. The thematic sessions of this Symposium are presented in the following: Experimental techniques for the unsteady ow separation Theoretical aspects and analytical approaches of ow separation Instability and transition Compressibility effects related to unsteady separation Statistical and hybrid turbulence modelling for unsteady separated ows Direct and Large-Eddy Simulation of unsteady separated ows Theoretical/industrial aspects of unsteady separated ow control This IUTAM Symposium concerned an important domain of Theoretical and Applied Mechanics nowadays. It focused on the problem of ow separation and of its control. It achieved a uni ed approach regrouping the knowledge provided from theoretical, experimental, numerical simulation and modelling aspects for unsteady separated ows (incompressible and compressible regimes) and included ef cient control devices to achieve attenuation or suppression of separation. The subject - eas covered important themes in the domain of fundamental research as well as in the domain of applications.
Download or read book Flow Induced Vibration Handbook for Nuclear and Process Equipment written by Michel J. Pettigrew and published by John Wiley & Sons. This book was released on 2021-12-09 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explains the mechanisms governing flow-induced vibrations and helps engineers prevent fatigue and fretting-wear damage at the design stage Fatigue or fretting-wear damage in process and plant equipment caused by flow-induced vibration can lead to operational disruptions, lost production, and expensive repairs. Mechanical engineers can help prevent or mitigate these problems during the design phase of high capital cost plants such as nuclear power stations and petroleum refineries by performing thorough flow-induced vibration analysis. Accordingly, it is critical for mechanical engineers to have a firm understanding of the dynamic parameters and the vibration excitation mechanisms that govern flow-induced vibration. Flow-Induced Vibration Handbook for Nuclear and Process Equipment provides the knowledge required to prevent failures due to flow-induced vibration at the design stage. The product of more than 40 years of research and development at the Canadian Nuclear Laboratories, this authoritative reference covers all relevant aspects of flow-induced vibration technology, including vibration failures, flow velocity analysis, vibration excitation mechanisms, fluidelastic instability, periodic wake shedding, acoustic resonance, random turbulence, damping mechanisms, and fretting-wear predictions. Each in-depth chapter contains the latest available lab data, a parametric analysis, design guidelines, sample calculations, and a brief review of modelling and theoretical considerations. Written by a group of leading experts in the field, this comprehensive single-volume resource: Helps readers understand and apply techniques for preventing fatigue and fretting-wear damage due to flow-induced vibration at the design stage Covers components including nuclear reactor internals, nuclear fuels, piping systems, and various types of heat exchangers Features examples of vibration-related failures caused by fatigue or fretting-wear in nuclear and process equipment Includes a detailed overview of state-of-the-art flow-induced vibration technology with an emphasis on two-phase flow-induced vibration Covering all relevant aspects of flow-induced vibration technology, Flow-Induced Vibration Handbook for Nuclear and Process Equipment is required reading for professional mechanical engineers and researchers working in the nuclear, petrochemical, aerospace, and process industries, as well as graduate students in mechanical engineering courses on flow-induced vibration.
Download or read book Cavity Flows written by Blaine Raphael Parkin and published by . This book was released on 1975 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:
