Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781721634903
Category :
Languages : en
Pages : 30
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Book Description
We have succeeded in measuring a substantial portion of the two-point space-time velocity correlation in hot, high speed turbulent jets. This measurement, crucial in aeroacoustic theory and the prediction of jet noise, has been sought for a long time, but has not been made due to the limitations of anemometry. Particle Image Velocimetry has reached a stage of maturity where sufficient measurement density in both time and space allow the computation of space-time correlations. This paper documents these measurements along with lower-order statistics to document the adherence of the jet rig and instrumentation to conventional measures of the turbulence of jets. These measures have been made for a simple round convergent nozzle at acoustic Mach numbers of 0.5, 0.9, both cold and at a static temperature ratio of 2.7, allowing some estimation of the changes in turbulence that take place with changes in jet temperature. Since the dataset described in this paper is very extensive, attention will be focused on validation of the rig and of the measurement systems, and on some of the interesting observations made from studying the statistics, especially as they relate to jet noise. Of note is the effort to study the acoustically relevant part of the space-time correlation by addressing that part of the turbulence kinetic energy that has sonic phase speed. Bridges, James and Wernet, Mark Glenn Research Center NASA/TM-2004-212508, AIAA Paper 2003-3130, E-14068
Author: Thomas J. Mueller
Publisher: Springer Science & Business Media
ISBN: 3662050587
Category : Technology & Engineering
Languages : en
Pages : 327
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Book Description
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.
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781721795246
Category :
Languages : en
Pages : 24
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Book Description
A 16 microphone phased-array system has been successfully applied to measure jet noise source distributions. In this study, a round convergent nozzle was tested at various hot and cold flow conditions: acoustic Mach numbers are between 0.35 and 1.6 and static temperature ratios are varied from cold to 2.7. The classical beamforming method was applied on narrowband frequencies. From the measured source distributions locations of peak strength were tracked and found to be very consistent between adjacent narrowband frequencies. In low speed heated and unheated jets, the peak source locations vary smoothly from the nozzle exit to downstream as the frequency is decreased. When the static temperature ratio was kept constant, the peak source position moved downstream with increasing acoustic Mach number for the Strouhal numbers smaller than about 1.5. It was also noted that the peak source locations of low frequencies occur farther downstream than the end of potential core. Bridges, James and Lee, Sang Soo Glenn Research Center NASA/TM-2005-213826, E-15185, AIAA Paper 2005-2842
Author: P.G. Tucker
Publisher: Springer Science & Business Media
ISBN: 9400770499
Category : Technology & Engineering
Languages : en
Pages : 432
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Book Description
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
Author: Harvey H. Hubbard
Publisher:
ISBN:
Category : Aerodynamic noise
Languages : en
Pages : 620
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Book Description
Author: Raimondas Ciegis
Publisher: Springer Science & Business Media
ISBN: 0387097074
Category : Mathematics
Languages : en
Pages : 287
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Book Description
Parallel Scientific Computing and Optimization introduces new developments in the construction, analysis, and implementation of parallel computing algorithms. This book presents 23 self-contained chapters, including survey chapters and surveys, written by distinguished researchers in the field of parallel computing. Each chapter is devoted to some aspects of the subject: parallel algorithms for matrix computations, parallel optimization, management of parallel programming models and data, with the largest focus on parallel scientific computing in industrial applications. This volume is intended for scientists and graduate students specializing in computer science and applied mathematics who are engaged in parallel scientific computing.
Author: James Bridges
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: André M. Hall
Publisher:
ISBN:
Category : Computational fluid dynamics
Languages : en
Pages : 66
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Book Description
The goal of this effort has been to identify the dominant source of the radiated aero-acoustic noise produced by high-speed, heated jets and develop control strategies to reduce it. To that end, two acoustically matched Mach 0.6 jets, at temperature ratio Tr=O.93 (cold) and Tr=1.7 (hot) are examined. The use of non-intrusive Particle Image Velocimetry (PIV) to sample the flow, allowed a true measure of the velocity field to be realized without fear of corrupting the radiated noise field intrinsic to each jet. The low-order modal dominance of each was determined using Proper Orthogonal Decomposition (POD), highlighting the low-dimensional nature of this highly turbulent flow field.
Author: Paul G. Tucker
Publisher: Cambridge University Press
ISBN: 1107075904
Category : Science
Languages : en
Pages : 589
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Book Description
This book outlines the computational fluid dynamics evolution and gives an overview of the methods available to the engineer.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 994
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Book Description
