Download or read book Turbulence Characterization and Control written by P. F. Kellen and published by . This book was released on 1976 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report covers activities relative to the characterization of the turbulent environment at the ARPA Maui Observation Station. Three areas are discussed. The first deals with the deployment of various instrumental systems to be used in the experimental program. These include micrometeorological sensors, a computer data processing system, and acoustic Sounder, the NOAA Star Sensor and the Hughes Seeing Monitor which are all presently operational.
Download or read book Analysis and Control of Turbulence with PIV written by Mika Piirto and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Turbulence Management and Relaminarisation written by H.W. Liepmann and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt: The last two decades have witnessed an intensifying effort in learning how to manage flow turbulence: it has in fact now become one of the most challenging and prized techno logical goals in fluid dynamics. The goal itself is of course not new. More than a hundred years ago, Reynolds already listed factors conducive to laminar and to turbulent flow (including among them curvature and acceleration). Further more, it is in retrospect clear that there were several early instances ot successful turbulence management. Examples are the reduction in drag achieved with a ring-trip placed on the front of a sphere or the insertion of a splitter-plate behind a circular cylinder; by the early 1950s there were numerous exercises at boundary layer control. Although many of these studies were interesting and suggestive, they led . to no spectacularly successful practical application, and the effort petered out in the late 1950s. The revival of interest in these problems in recent years can be attributed to the emergence of several new factors. First of all, fresh scientific insight into the structure of turbulence, in particular the accumulated evidence for the presence of significant order in turbulent flow, has been seen to point to new methods of managing turbulence. A second major reason has been the growing realisation that the rate at which the world is consuming its reserves of fossil fuels is no longer negligible; the economic value of greater energy effi ciency and lower drag has gone up significantly.
Download or read book Turbulent Flow written by Peter S. Bernard and published by John Wiley & Sons. This book was released on 2002-08-19 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides unique coverage of the prediction and experimentation necessary for making predictions. * Covers computational fluid dynamics and its relationship to direct numerical simulation used throughout the industry. * Covers vortex methods developed to calculate and evaluate turbulent flows. * Includes chapters on the state-of-the-art applications of research such as control of turbulence.
Download or read book Principles of Turbulence Control written by Baochun Fan and published by John Wiley & Sons. This book was released on 2022-05-17 with total page 397 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces the mathematical techniques for turbulence control in a form suitable for inclusion in an engineering degree program at both undergraduate and postgraduate levels whilst also making it useful to researchers and industrial users of the concepts. It uses a mix of theory, computation and experimental results to present and illustrate the methodologies. It is based on the three part structure, wall turbulence, open loop control and feedback control with emphasis on optimal control methodologies. The book also includes an introduction of basic principles and fundamentals followed by a chapter on the structure of wall turbulence with emphasis on coherent structures. Elsewhere there is focus on control methods of wall turbulence by manipulating the boundaries though their motion and by applying control forces throughout the flow volume. The last two chapters will describe the linear and non-linear optimal controls. This integrated approach will help not only researchers interested in the topic but also graduate or advanced undergraduate students in their course work.
Download or read book Wall Turbulence Control written by Sedat Tardu and published by John Wiley & Sons. This book was released on 2017-05-01 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wall turbulence control is a major subject, the investigation of which involves significant industrial, environmental and fundamental consequences. Wall Turbulence Control addresses recent advances achieved in active and passive wall turbulence control over the past two decades. This valuable reference for scientists, researchers and engineers provides an updated view of the research into this topic, including passive control, optimal and suboptimal control methodology, linear control and control using adaptive methods (neural networks), polymer and bubble injection, electromagnetic control and recent advances in control by plasma.
Download or read book Transition and Turbulence Control written by Mohamed Gad-el-Hak and published by World Scientific. This book was released on 2006 with total page 445 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains articles based on lectures given at the Workshop on Transition and Turbulence Control, hosted by the Institute for Mathematical Sciences, National University of Singapore, 8-10 December 2004. The lecturers included 13 of the world's foremost experts in the control of transitioning and turbulent flows. The chapters cover a wide range of subjects in the broad area of flow control, and will be useful to researchers working in this area in academia, government laboratories and industry. The coverage includes control theory, passive, active and reactive methods for controlling transitional and turbulent wall-bounded flows, noise suppression and mixing enhancement of supersonic turbulent jets, compliant coatings, modern flow diagnostic systems, and swept wing instabilities.
Download or read book REDUCED ORDER CHARACTERIZATION OF THE AEROELASTIC RESPONSE OF STALL CONTROLLED WIND TURBINES UNDER ATMOSPHERIC TURBULENCE written by and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Wind, by its vary nature, varies with place and time, making energy conversion difficult. This calls for the development of improved technologies that efficiently harness energy from the available wind resource, and advanced control systems are a key research aspect of wind turbine technology. Such systems are needed to maximize the rotor's output power at wind speeds below the nominal value for the turbine, limit rotor power at wind speeds higher than the nominal, and reduce fluctuating loads on the turbine blades that may compromise their long-term operational life. Among the several families of control methods for wind turbines, Pitch and Stall are by far the most used in modern utility-scale machines. Both are based on altering the aerodynamic characteristics of the blade sections in order to control the forces which produce the rotor's torque, power, and thrust, and its deformation. A very popular control method to optimize power production and control is using Variable-Speed Wind Turbines (VSWT) a relatively new idea, which offers has a promising perspective for future applications. As with the classical Fixed-Speed (FS) stall method lowers the capital cost and reduces maintenance expenses, while at the same time, allows for a more efficient and precise control of power production. This research investigated the aeroselastic behavior of the stall-controlled rotors, studied the frequency content and time evolution of their oscillatory behavior, and gained a better understanding of the underlying physics. This calls for a wide range of experiments that assess the effects of rapid variations on the rotor's operational conditions, like gusts and turbulent fluctuations on the wind flow. To systematize this analysis, various gust conditions tested for different wind speeds. These are represented by pulses of different intensity, occurring suddenly in and otherwise constant wind regime. This allows us to observe the pure aero-elasto-inertial dynamics of the rotor's response. We will show the results from an extensive series of experiments analyzing the aeroelastic response of the rotor to wind speed fluctuations associated to the turbulent characteristics of the atmospheric boundary layer, focusing on obtaining a reduced-order characterization of the rotor's dynamics as an oscillatory system based on energy-transfer principles. Besides on its intrinsic scientific value, this aspect of the work presented here is of fundamental interest for researchers and engineers working on developing optimized control strategies for wind turbines. It allows for the critical elements of the rotor's dynamic behavior to be described as a reduced-order model that can be solved in real-time, an essential requirement for determining predictive control actions.
Download or read book The Development of a Rapid Vertical Profiling Technique for Turbulence Measurements written by Miyuki Takagi and published by . This book was released on 2002 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Optical Turbulence Astronomy Meets Meteorology Proceedings Of The Optical Turbulence Characterization For Astronomical Applications written by Elena Masciadri and published by World Scientific. This book was released on 2009-09-14 with total page 415 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book collects most of the talks and poster presentations presented at the 'Optical Turbulence — Astronomy meets Meteorology' international conference held on 15-18 September, 2008 at Nymphes Bay, Alghero, Sardinia, Italy. The meeting aimed to deal with one of the major causes of wavefront perturbations limiting the astronomical high-angular-resolution observations from the ground. The uniqueness of this meeting has been the effort to attack this topic in a synergic and multidisciplinary approach promoting constructive discussions between the actors of this science — the astronomers, meteorologists, physicists of the atmosphere and the experts in adaptive optics and interferometry techniques whose main goal is to correct, in real-time, the wavefront perturbations induced by atmospheric turbulence to restore at the telescope foci the best available image quality./a
Download or read book Characterization of the Flow Field Wind Speed Profiles and Turbulence Intensity in Environmental Wind Tunnels for Measurement of Agent Fate written by and published by . This book was released on 2005 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface evaporation and desorption sub-models in VLSTRACK require measurements of chemical warfare agent evaporation and desorption under environmental conditions. A 5cm square by approximately I meter wind tunnel for chemical agent measurements was developed with optional strakes and roughening elements to add turbulence. Flow was developed in the pull-mode by an electric blower system. Several candidate intake geometries were designed that allowed controlled restriction of air intake to control wind speed. The flow field was characterized as a function of several intake control geometries and as a function of the presence or absence of the turbulence elements. A micrometer positioning device was employed to traverse the wind tunnel cross section with a subminiature hot wire anemometer. A TSI Model IFA-300, temperature-compensated, hot wire anemometry system was utilized for all measurements. The experimental and computational fluid dynamic flow field results were documented. The tipper and lower limits of wind speed available from the electric blower and intake restriction systems were determined. The symmetry of the flow field with and without turbulence elements was also determined. The chemical droplets are placed on substrates on the floor of the wind tunnel; therefore, flow field measurements close to the floor were emphasized. Finally, the reproducibility of the wind speed was measured as a function of blower power settings and intake restrictions levels.
Download or read book Turbulent Reactive Flows written by R. Borghi and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 958 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulent reactive flows are of common occurrance in combustion engineering, chemical reactor technology and various types of engines producing power and thrust utilizing chemical and nuclear fuels. Pollutant formation and dispersion in the atmospheric environment and in rivers, lakes and ocean also involve interactions between turbulence, chemical reactivity and heat and mass transfer processes. Considerable advances have occurred over the past twenty years in the understanding, analysis, measurement, prediction and control of turbulent reactive flows. Two main contributors to such advances are improvements in instrumentation and spectacular growth in computation: hardware, sciences and skills and data processing software, each leading to developments in others. Turbulence presents several features that are situation-specific. Both for that reason and a number of others, it is yet difficult to visualize a so-called solution of the turbulence problem or even a generalized approach to the problem. It appears that recognition of patterns and structures in turbulent flow and their study based on considerations of stability, interactions, chaos and fractal character may be opening up an avenue of research that may be leading to a generalized approach to classification and analysis and, possibly, prediction of specific processes in the flowfield. Predictions for engineering use, on the other hand, can be foreseen for sometime to come to depend upon modeling of selected features of turbulence at various levels of sophistication dictated by perceived need and available capability.
Download or read book Flight Stability and Automatic Control written by Robert C. Nelson and published by WCB/McGraw-Hill. This book was released on 1998 with total page 441 pages. Available in PDF, EPUB and Kindle. Book excerpt: The second edition of Flight Stability and Automatic Control presents an organized introduction to the useful and relevant topics necessary for a flight stability and controls course. Not only is this text presented at the appropriate mathematical level, it also features standard terminology and nomenclature, along with expanded coverage of classical control theory, autopilot designs, and modern control theory. Through the use of extensive examples, problems, and historical notes, author Robert Nelson develops a concise and vital text for aircraft flight stability and control or flight dynamics courses.
Download or read book Experimental and Numerical Characterization of Turbulence in Fluid Flow written by Jalal Mohammed Zayan and published by . This book was released on 2015 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents experimental measurements on a round free turbulent jet and numerical simulations on a flow past a surface mounted cylinder. The experimental measurements map the Reynolds stresses in a vertical round free jet. A 12 mm diameter nozzle with exit velocity of 8 m/s with corresponding Reynolds number of 6000 were used to determine the differences in mean velocity profiles, turbulence intensity profiles, and velocity spectra in the flow of a vertical round free jet at room conditions. Constant Temperature Anemometry (CTA) with 1D probe was used to measure the mean and fluctuating velocity components to obtain the Reynolds stress correlations. The results show that different mechanisms may have control in various types jet flows or in different regions of a jet flow. In free jet flows, the downstream region is dominated by turbulence structure whereas coherent eddy-structure can have a strong influence on the near field; particularly for low-Reynolds number jet flows. The present study is an attempt to review the current information on vertical round free turbulent jet flows. The influence of origin of the jet (initial conditions) and the boundary conditions on the jet flow structure is considered. The result depicts that the exit conditions of the jet play a very important role in the development of the jet in the near field but the far field flow remains independent of the exit conditions of the jet. The numerical solution is preform by using large eddy simulations (LES) for the flow around a surface mounted cylinder. Cylinder of height-to-diameter ratios of 2.5 with a thin boundary layer of the approach flow have been analyzed and compared to the available literature using StarCCM+. The detailed study presented confirms largely the flow behavior of the fluid flow comprehensively when the fluid interacts with a bluff (solid) body (cylinder). It also provides further insight and quantitative information on the mean flow, the turbulent fluctuations and the unsteady flow features. The mean-flow behavior is analyzed with the aid of streamlines and contour plots of mean-velocity and fluctuation components. The vortex shedding flow pattern past the cylinder is further analyzed for determining the Reynolds stresses. Alternating shedding is found to occur over the cylinder. The shedding is observed mainly near the ground where it is also mostly alternating but intermittently also symmetrical. The aim of the work is to characterize turbulence in a fluid flow in terms of Reynolds stresses.
Download or read book An Introduction to Turbulence and its Measurement written by P Bradshaw and published by Elsevier. This book was released on 2013-10-22 with total page 239 pages. Available in PDF, EPUB and Kindle. Book excerpt: An Introduction to Turbulence and Its Measurement is an introductory text on turbulence and its measurement. It combines the physics of turbulence with measurement techniques and covers topics ranging from measurable quantities and their physical significance to the analysis of fluctuating signals, temperature and concentration measurements, and the hot-wire anemometer. Examples of turbulent flows are presented. This book is comprised of eight chapters and begins with an overview of the physics of turbulence, paying particular attention to Newton's second law of motion, the Newtonian viscous fluid, and equations of motion. After a chapter devoted to measurable quantities, the discussion turns to some examples of turbulent flows, including turbulence behind a grid of bars, Couette flow, atmospheric and oceanic turbulence, and heat and mass transfer. The next chapter describes measurement techniques using hot wires, films, and thermistors, as well as Doppler-shift anemometers; glow-discharge or corona-discharge anemometers; pulsed-wire anemometer; and steady-flow techniques for fluctuation measurement. This monograph is intended for post-graduate students of aeronautics and fluid mechanics, but should also be readily understandable to those with a good general background in engineering fluid dynamics.
Download or read book Optical Turbulence written by Elena Masciadri and published by Imperial College Press. This book was released on 2009 with total page 415 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book collects most of the talks and poster presentations presented at the Optical Turbulence OCo Astronomy meets Meteorology international conference held on 15OCo18 September, 2008 at Nymphes Bay, Alghero, Sardinia, Italy. The meeting aimed to deal with one of the major causes of wavefront perturbations limiting the astronomical high-angular-resolution observations from the ground. The uniqueness of this meeting has been the effort to attack this topic in a synergic and multidisciplinary approach promoting constructive discussions between the actors of this science OCo the astronomers, meteorologists, physicists of the atmosphere and the experts in adaptive optics and interferometry techniques whose main goal is to correct, in real-time, the wavefront perturbations induced by atmospheric turbulence to restore at the telescope foci the best available image quality. Sample Chapter(s). Chapter 1: Optical Turbulence in High Angular Resolution Techniques in Astronomy (494 KB). Contents: Optical Turbulence in High Angular Resolution Techniques in Astronomy (J M Beckers); Optical Turbulence Profiles at CTIO from a 12-Element Lunar Scintillometer (P Hickson et al.); High Resolution SLODAR Measurements on Mauna Kea (T Butterley et al.); How We Can Understand the Antarctic Atmospheric? (J W V Storey et al.); The Paranal Surface Layar (J Melnick et al.); Introduction to Data Assimilation in Meteorology (P Brousseau OC L Auger); The Mauna Kea Weather Center: A Case for Custom Seeing Forecasts (T Cherubini et al.); Dealing with Turbulence: MCAO Experience and Beyond (R Ragazzoni et al.); Future-Look Science Operations for the LBT (R F Green); Surface Layer SLODAR (J Osborn et al.); and other papers. Readership: Advanced undergraduates and graduate students, and physicists working in the field of astronomy.
Download or read book Advances in Effective Flow Separation Control for Aircraft Drag Reduction written by Ning Qin and published by Springer Nature. This book was released on 2019-10-17 with total page 341 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the results of a European-Chinese collaborative research project, Manipulation of Reynolds Stress for Separation Control and Drag Reduction (MARS), including an analysis and discussion of the effects of a number of active flow control devices on the discrete dynamic components of the turbulent shear layers and Reynolds stress. From an application point of view, it provides a positive and necessary step to control individual structures that are larger in scale and lower in frequency compared to the richness of the temporal and spatial scales in turbulent separated flows.
