Direct Measurement of the Mode O Turbulent Boundary Layer Wall Pressure and Wall Shear Stress Spectra Using Air-Backed and Oil-Filled Multichannel Wavenumber Filters PDF Download
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Author:
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ISBN:
Category :
Languages : en
Pages : 153
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Book Description
This report describes research that resulted in the first direct multichannel measurements of the wall pressure and wall shear stress spectra beneath a turbulent boundary layer formed over a long, thin cylinder in an axial flow field. These measurements, processed as wavenumber-frequency spectra, were made with a multichannel array composed of an air-backed cylinder structure and a 32-channel aperture of PVDF film sensors having an axisymmetric response with respect to the array circumference. The measurements resolve the wavenumber spectrum in the +/- 131-rad/m range. Unexpected results were observed at a 5-knot freestream flow speed, where the magnitude of the wall shear stress convective ridge level exceeded the magnitude of the wall pressure convective ridge level. From 10 to 20 knots, the traditional relationship was observed, in which the wall pressure magnitude exceeds the wall shear stress magnitude in the vicinity of the convective ridge. Additionally, accurate resolution of the shape of the convective ridge as a function of wavenumber was accomplished with the air-backed cylinder array. An experimental calibration of the "hose transfer function" for pressure was obtained by using data from an array of ceramic hydrophones mounted interior to an oil-filled cylinder in unison with data from the air-backed cylinder array. Theoretical dynamic elasticity simulations were required to remove the effects of the surface-generated pressure fields, which were different for each structure. Previous to this research, a mathematical model of the hose transfer function was used without the aid of experimental data or verification of any kind. The oil-filled array measurements spanned the wavenumber spectrum in the +/- 206-rad/m range and included measurements at kappa = 0 that were free from acoustic contamination.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 153
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Book Description
This report describes research that resulted in the first direct multichannel measurements of the wall pressure and wall shear stress spectra beneath a turbulent boundary layer formed over a long, thin cylinder in an axial flow field. These measurements, processed as wavenumber-frequency spectra, were made with a multichannel array composed of an air-backed cylinder structure and a 32-channel aperture of PVDF film sensors having an axisymmetric response with respect to the array circumference. The measurements resolve the wavenumber spectrum in the +/- 131-rad/m range. Unexpected results were observed at a 5-knot freestream flow speed, where the magnitude of the wall shear stress convective ridge level exceeded the magnitude of the wall pressure convective ridge level. From 10 to 20 knots, the traditional relationship was observed, in which the wall pressure magnitude exceeds the wall shear stress magnitude in the vicinity of the convective ridge. Additionally, accurate resolution of the shape of the convective ridge as a function of wavenumber was accomplished with the air-backed cylinder array. An experimental calibration of the "hose transfer function" for pressure was obtained by using data from an array of ceramic hydrophones mounted interior to an oil-filled cylinder in unison with data from the air-backed cylinder array. Theoretical dynamic elasticity simulations were required to remove the effects of the surface-generated pressure fields, which were different for each structure. Previous to this research, a mathematical model of the hose transfer function was used without the aid of experimental data or verification of any kind. The oil-filled array measurements spanned the wavenumber spectrum in the +/- 206-rad/m range and included measurements at kappa = 0 that were free from acoustic contamination.
Author: Andreas Dillmann
Publisher: Springer
ISBN: 3319272799
Category : Technology & Engineering
Languages : en
Pages : 855
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Book Description
This book presents contributions to the 19th biannual symposium of the German Aerospace Aerodynamics Association (STAB) and the German Society for Aeronautics and Astronautics (DGLR). The individual chapters reflect ongoing research conducted by the STAB members in the field of numerical and experimental fluid mechanics and aerodynamics, mainly for (but not limited to) aerospace applications, and cover both nationally and EC-funded projects. Special emphasis is given to collaborative research projects conducted by German scientists and engineers from universities, research-establishments and industries. By addressing a number of cutting-edge applications, together with the relevant physical and mathematics fundamentals, the book provides readers with a comprehensive overview of the current research work in the field. Though the book’s primary emphasis is on the aerospace context, it also addresses further important applications, e.g. in ground transportation and energy.
Author: M.Y. Hussaini
Publisher: Springer Science & Business Media
ISBN: 1461234328
Category : Science
Languages : en
Pages : 509
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Book Description
The ability to predict and control viscous flow phenomena is becoming increasingly important in modern industrial application. The Instability and Transition Workshop at Langley was extremely important in help§ ing the scientists community to access the state of knowledge in the area of transition from laminar to turbulent flow, to identify promising future areas of research and to build future interactions between researchers worldwide working in the areas of theoretical, experimental and computational fluid and aero dynamics. The set of two volume contains panel discussions and research contribution with the following objectives: (1) expose the academic community to current technologically important issues of instability and transitions in shear flows over the entire speed range, (2) acquaint the academic community with the unique combination of theoretical, computational and experimental capabilities at LaRC and foster interaction with these facilities. (3) review current state-of-the-art and propose future directions for instability and transition research, (4) accelerate progress in elucidating basic understanding of transition phenomena and in transferring this knowledge into improved design methodologies through improved transition modeling, and (5) establish mechanism for continued interaction.
Author: Martin Oberlack
Publisher: Springer
ISBN: 3709125642
Category : Science
Languages : en
Pages : 377
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Book Description
The term "turbulence” is used for a large variety of dynamical phenomena of fluids in motion whenever the details of the flow appear to be random and average properties are of primary interest. Just as wide ranging are the theoretical methods that have been applied towards a better understanding of fluid turbulence. In this book a number of these methods are described and applied to a broad range of problems from the transition to turbulence to asymptotic turbulence when the inertial part of the spectrum is fully developed. Statistical as well as nonstatistical treatments are presented, but a complete coverage of the subject is not attempted. The book will be of interest to scientists and engineers who wish to familiarize themselves with modern developments in theories of turbulence. The fact that the properties of turbulent fluid flow are addressed from very different points of view makes this volume rather unique among presently available books on turbulence.
Author: Paul Manneville
Publisher: World Scientific
ISBN: 1848163924
Category : Science
Languages : en
Pages : 456
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Book Description
This book (2nd edition) is a self-contained introduction to a wide body of knowledge on nonlinear dynamics and chaos. Manneville emphasises the understanding of basic concepts and the nontrivial character of nonlinear response, contrasting it with the intuitively simple linear response. He explains the theoretical framework using pedagogical examples from fluid dynamics, though prior knowledge of this field is not required. Heuristic arguments and worked examples replace most esoteric technicalities. Only basic understanding of mathematics and physics is required, at the level of what is currently known after one or two years of undergraduate training: elementary calculus, basic notions of linear algebra and ordinary differential calculus, and a few fundamental physical equations (specific complements are provided when necessary). Methods presented are of fully general use, which opens up ample windows on topics of contemporary interest. These include complex dynamical processes such as patterning, chaos control, mixing, and even the Earth's climate. Numerical simulations are proposed as a means to obtain deeper understanding of the intricacies induced by nonlinearities in our everyday environment, with hints on adapted modelling strategies and their implementation.
Author:
Publisher:
ISBN:
Category : Aircraft industry
Languages : en
Pages : 8
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Book Description
Author: John P. Bentley
Publisher: Longman Scientific and Technical
ISBN:
Category : Science
Languages : en
Pages : 528
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Book Description
Covers techniques and theory in the field, for students in degree courses for instrumentation/control, mechanical manufacturing, engineering, and applied physics. Three sections discuss system performance under static and dynamic conditions, principles of signal conditioning and data presentation, and applications. This third edition incorporates recent developments in computing, solid-state electronics, and optoelectronics. Includes problems and bandw diagrams. Annotation copyright by Book News, Inc., Portland, OR
Author: Zinoviy Nazarchuk
Publisher: Springer
ISBN: 3319493507
Category : Technology & Engineering
Languages : en
Pages : 294
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Book Description
This monograph analyses in detail the physical aspects of the elastic waves radiation during deformation or fracture of materials. It presents the methodological bases for the practical use of acoustic emission device, and describes the results of theoretical and experimental researches of evaluation of the crack growth resistance of materials, selection of the useful AE signals. The efficiency of this methodology is shown through the diagnostics of various-purpose industrial objects. The authors obtain results of experimental researches with the help of the new methods and facilities.
Author:
Publisher:
ISBN:
Category : Aerodynamic load
Languages : en
Pages : 262
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Book Description
Author: Nam-Trung Nguyen
Publisher: Integrated Microsystems
ISBN: 9781630813642
Category : Fluidic devices
Languages : en
Pages : 0
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Book Description
Now in its Third Edition, the Artech House bestseller, Fundamentals and Applications of Microfluidics, provides engineers and students with the most complete and current coverage of this cutting-edge field. This revised and expanded edition provides updated discussions throughout and features critical new material on microfluidic power sources, sensors, cell separation, organ-on-chip and drug delivery systems, 3D culture devices, droplet-based chemical synthesis, paper-based microfluidics for point-of-care, ion concentration polarization, micro-optofluidics and micro-magnetofluidics. The book shows how to take advantage of the performance benefits of microfluidics and serves as an instant reference for state-of-the-art microfluidics technology and applications. Readers find discussions on a wide range of applications, including fluid control devices, gas and fluid measurement devices, medical testing equipment, and implantable drug pumps. Professionals get practical guidance in choosing the best fabrication and enabling technology for a specific microfluidic application, and learn how to design a microfluidic device. Moreover, engineers get simple calculations, ready-to-use data tables, and rules of thumb that help them make design decisions and determine device characteristics quickly. addressed at the design stage to reduce the risk of failures in the field is presented. The book includes technical details of all state-of-the-art Li-on energy storage subsystems and their requirements, and provides a system designer a single resource detailing all of the common issues navigated when using Li-ion batteries to reduce the risk of field failures. The book details the various industry standards that are applicable to the subsystems of Li-ion energy storage systems and how the requirements of these standards may impact the design of their system. Checklists are included to help readers evaluate their own battery system designs and identify gaps in the designs that increase the risk of field failures. The book is packed with numerous examples of issues that have caused field failures and how a proper design/assembly process could have reduced the risk of these failures.
