Download or read book Active Control of High Reynolds Number Supersonic Jets Using Plasma Actuators written by and published by . This book was released on 2010 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: Active flow control of jets with Localized Arc Filament Plasma Actuators (LAFPAs) is conducted over a wide range of the fully expanded jet Mach numbers (M(J) or simply jet Mach number). The jet Mach numbers covered in the present research are 0.9 (with a converging nozzle), 1.2 (overexpanded), 1.3 (perfectly expanded), and 1.4 (underexpanded) with a design Mach number 1.3. Additionally, limited experiments are carried out for an M(J) = 1.65 perfectly-expanded jet. The exit diameter is 2.54 cm (1 inch) for all cases and eight LAFPAs are equally distributed on the perimeter of a boron nitride nozzle extension. The jet spreading is strongly dependent on duty cycle, forcing frequency, and azimuthal modes. The performance of LAFPAs for jet spreading is investigated using two-dimensional particle image velocimetry (PIV). There is an optimum duty cycle, producing maximum jet spreading, for each forcing frequency. A relationship between the optimum duty cycle and forcing frequency is determined from the extensive results in the MJ 0.9, and this relation is used for all experiments. The effect of forcing frequency is investigated for a wide range of forcing Strouhal numbers (StDF = f(F)D/U(e), where f(F), D, and U(e), are forcing frequency, nozzle exit diameter, and jet exit velocity respectively), ranging from 0.09 to 3.0. The azimuthal modes (m) investigated are m = 0 - 3, +/-1, +/-2, and +/-4 - this comprises all modes available with eight actuators. The performance of LAFPAs does also strongly depend on the stagnation temperature of the jet and M(J). The effects of stagnation temperature are investigated for 1.0, 1.4, and 2.0 times the ambient temperature in M(J) 0.9 jet for very limited azimuthal modes and St(DF). In an M(J) 1.65 perfectly-expanded jet, the control authority of LAFPAs is investigated for only m = +/-1 and St(DF) tilde 0.3.
Download or read book Active Control of Supersonic Jets Operating in Various Flow Regimes written by Robert Michael Snyder and published by . This book was released on 2008 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The flow through the exhaust nozzle of a jet engine has been of crucial importance in aerospace applications over the past several decades. A variety of modifications can be made to the nozzles of high-speed jet engines to increase or decrease mixing between the exiting flow and the ambient air; including adding tabs, chevrons, or actuators. Localized arc filament plasma actuators (LAFPAs) developed in the Gas Dynamics and Turbulence Laboratory at The Ohio State University have both high amplitude and bandwidth and are suitable for active control of high-speed, high Reynolds number flows. LAFPAs were used to control a supersonic jet from an axisymmetric nozzle of design Mach number of 1.3 operating from overexpanded to underexpanded flow regimes with the fully expanded jet Mach number (MJ) from 1.1 to 1.5 in order to explore their characteristics and their potential for mixing enhancement between the jet and the ambient air. The Reynolds number based on the 2.54 cm nozzle exit diameter was from 1.0x106 to 1.4x106. Laser based planar flow visualizations, schlieren imaging, and particle image velocimetry measurements were used to evaluate the effects of control. Results show the effects of forcing frequency and other parameters on the development of large-scale structures within the flow. Eight actuators, distributed azimuthally approximately 1 mm upstream of the nozzle exit, were used to force various azimuthal modes over a large Strouhal number range (StDF of 0.07 to 2.68). The preliminary results in underexpanded jets (MJ = 1.4 and 1.5) were quite similar to results in the ideally expanded jet (MJ = 1.3) previously obtained in similar studies at GDTL. The ideally expanded jet responded to the forcing over the entire range of frequencies, but the response was optimum (in terms of development of large coherent structures and mixing enhancement) around the jet preferred Strouhal number of 0.34 (fF = 5 kHz). Similarly, the optimum response was found at a jet preferred Strouhal number of 0.27 (fF = 4 kHz) for the slightly underexpanded jet (MJ = 1.4) and 0.34 (fF = 5 kHz) for the strongly underexpanded jet (MJ = 1.5). The jet also responded to forcing with various azimuthal modes (m=0 to 3 and m= ± 1, ±2, ±4). Forcing the jet with the azimuthal mode m= ±1 at the jet preferred mode frequency provided the maximum mixing enhancement in the visualized plane. Conversely, the preliminary results showed that the overexpanded jets (MJ = 1.1 and 1.2) did not respond at all or the response was relatively small. Subsequent surface pressure measurements with an extension without actuators revealed significant pressure increases near the nozzle exit for the strongly overexpanded MJ = 1.1 case, suggesting the existence of flow separation. Flow separation would cause the flow to pass over actuator location, thus nullifying the effect of control.
Download or read book Mixing Control in Supersonic Rectangular Jets Using Plasma Actuators written by Robert M. Snyder and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The flow through the exhaust nozzle of a jet engine has been of crucial importance in aerospace applications over the past several decades. A variety of modifications can be made to the nozzles of high-speed jet engines to increase or decrease mixing between the exiting flow and the ambient air; including adding tabs, chevrons, or actuators. Localized arc filament plasma actuators (LAFPA) developed in the Gas Dynamics and Turbulence Laboratory at The Ohio State University have both high amplitude and bandwidth and are suitable for active control of high-speed, high Reynolds number flows. These actuators were implemented on a rectangular nozzle in order to optimize the efficiency of mixing enhancement between the jet and the ambient air. Actuators were tested for a Mach 2.0 flow over a wide range of forcing frequencies and the effects were evaluated using flow visualization techniques. Results show the effects of forcing frequency and other parameters on the development of large-scale structures within the flow. Flow visualization testing over a broad range of forcing frequencies and duty cycles revealed the presence of large coherent structures and thus most favorable mixing enhancement in the 6-8 kHz (StF = 0.15-0.2) range. The m = " 1 (flapping) mode produced a clear pattern of alternating structures within the aforementioned frequency band. It was also observed that the effect of varying duty cycle within this frequency range has little effect on the control authority.
Download or read book Active Flow and Combustion Control 2018 written by Rudibert King and published by Springer. This book was released on 2018-09-03 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book reports on the latest theoretical and experimental findings in the field of active flow and combustion control. It covers new developments in actuator technology and sensing, in robust and optimal open- and closed-loop control, as well as in model reduction for control, constant volume combustion and dynamic impingement cooling. The chapters reports oncutting-edge contributions presented during the fourth edition of the Active Flow and Combustion Control conference, held in September 19 to 21, 2018 at the Technische Universität Berlin, in Germany. This conference, as well as the research presented in the book, have been supported by the collaborative research center SFB 1029 on “Substantial efficiency increase in gas turbines through direct use of coupled unsteady combustion and flow dynamics”, funded by the DFG (German Research Foundation). It offers a timely guide for researchers and practitioners in the field of aeronautics, turbomachinery, control and combustion.
Download or read book Applied Aerodynamics written by Jorge Colman Lerner and published by BoD – Books on Demand. This book was released on 2012-05-11 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aerodynamics, from a modern point of view, is a branch of physics that study physical laws and their applications, regarding the displacement of a body into a fluid, such concept could be applied to any body moving in a fluid at rest or any fluid moving around a body at rest. This Book covers a small part of the numerous cases of stationary and non stationary aerodynamics; wave generation and propagation; wind energy; flow control techniques and, also, sports aerodynamics. It's not an undergraduate text but is thought to be useful for those teachers and/or researchers which work in the several branches of applied aerodynamics and/or applied fluid dynamics, from experiments procedures to computational methods.
Download or read book Flow Control Techniques and Applications written by Jinjun Wang and published by Cambridge University Press. This book was released on 2019 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: Master the theory, applications and control mechanisms of flow control techniques.
Download or read book Advances in Heat Transfer and Fluid Dynamics written by Mohammad Altamush Siddiqui and published by Springer Nature. This book was released on with total page 425 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Low Reynolds Number written by Mustafa Serdar Genç and published by BoD – Books on Demand. This book was released on 2012-04-04 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reports the latest development and trends in the low Re number aerodynamics, transition from laminar to turbulence, unsteady low Reynolds number flows, experimental studies, numerical transition modelling, control of low Re number flows, and MAV wing aerodynamics. The contributors to each chapter are fluid mechanics and aerodynamics scientists and engineers with strong expertise in their respective fields. As a whole, the studies presented here reveal important new directions toward the realization of applications of MAV and wind turbine blades.
Download or read book Flow Control written by Thomas C. Corke and published by Cambridge University Press. This book was released on 2024-04-11 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive treatment of passive and active flow control in fluid dynamics, with an emphasis on utilizing fluid instabilities for enhancing control performance. Examples are given from a wide range of technologically important flow fields occurring in aerospace applications, from low-subsonic to hypersonic Mach numbers. This essential book can be used for both research and teaching on the topics of fluid instabilities, fluid measurement and flow actuator techniques, and problem sets are provided at the end of each chapter to reinforce key concepts and further extend readers' understanding of the field. The solutions manual is available as a online resource for instructors. The text is well suited for both graduate students in fluid dynamics and for practising engineers in the aerodynamics design field.
Download or read book Encyclopedia of Plasma Technology Two Volume Set written by J. Leon Shohet and published by CRC Press. This book was released on 2016-12-12 with total page 1654 pages. Available in PDF, EPUB and Kindle. Book excerpt: Technical plasmas have a wide range of industrial applications. The Encyclopedia of Plasma Technology covers all aspects of plasma technology from the fundamentals to a range of applications across a large number of industries and disciplines. Topics covered include nanotechnology, solar cell technology, biomedical and clinical applications, electronic materials, sustainability, and clean technologies. The book bridges materials science, industrial chemistry, physics, and engineering, making it a must have for researchers in industry and academia, as well as those working on application-oriented plasma technologies. Also Available Online This Taylor & Francis encyclopedia is also available through online subscription, offering a variety of extra benefits for researchers, students, and librarians, including: Citation tracking and alerts Active reference linking Saved searches and marked lists HTML and PDF format options Contact Taylor and Francis for more information or to inquire about subscription options and print/online combination packages. US: (Tel) 1.888.318.2367; (E-mail) [email protected] International: (Tel) +44 (0) 20 7017 6062; (E-mail) [email protected]
Download or read book Compressibility Turbulence and High Speed Flow written by Thomas B. Gatski and published by Academic Press. This book was released on 2013-03-05 with total page 343 pages. Available in PDF, EPUB and Kindle. Book excerpt: Compressibility, Turbulence and High Speed Flow introduces the reader to the field of compressible turbulence and compressible turbulent flows across a broad speed range, through a unique complimentary treatment of both the theoretical foundations and the measurement and analysis tools currently used. The book provides the reader with the necessary background and current trends in the theoretical and experimental aspects of compressible turbulent flows and compressible turbulence. Detailed derivations of the pertinent equations describing the motion of such turbulent flows is provided and an extensive discussion of the various approaches used in predicting both free shear and wall bounded flows is presented. Experimental measurement techniques common to the compressible flow regime are introduced with particular emphasis on the unique challenges presented by high speed flows. Both experimental and numerical simulation work is supplied throughout to provide the reader with an overall perspective of current trends. - An introduction to current techniques in compressible turbulent flow analysis - An approach that enables engineers to identify and solve complex compressible flow challenges - Prediction methodologies, including the Reynolds-averaged Navier Stokes (RANS) method, scale filtered methods and direct numerical simulation (DNS) - Current strategies focusing on compressible flow control
Download or read book Boundary Layer Flows Advances in Experimentation Modelling and Simulation written by Zambri Harun and published by BoD – Books on Demand. This book was released on 2024-07-24 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluid mechanics is a branch of physics with important applications in daily life. The calculation of flow drag on automobiles and high-speed trains benefits from theories in fluid mechanics. Moreover, many mechanical-based devices such as fluid pumps contribute to efficiency, and thus, to the modernization of society. This book highlights the experimental and theoretical aspects of wall-bounded flows to provide important information about related theories and applications. Boundary layer flow experimentation, modelling, and simulation must be considered together to obtain accurate calculations of parameters such as velocity profiles, pressure distribution, and turbulence level. This book is organized into three sections on the structure of the boundary layer, drag reduction initiatives using active control, and the verification and applications of flow mechanics. Chapters discuss the boundary layer type of different pressure gradients, Reynolds number, and speeds from 5 m/s to Mach 3. They also present the results of research on the active control technique for drag reduction initiatives to achieve efficient turbulence in high-speed applications, flow meter devices, and turbulence-generated noise mitigation initiatives.
Download or read book Active Control of High Speed Subsonic Cavity Flow Using Plasma Actuators written by Douglas Alan Mitchell and published by . This book was released on 2007 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The study and control of cavity flow fields began in the 1950's and has remained an active area of research for the past fifty years. Grazing flow over an open cavity which leads to resonance is a common occurrence generated by the flow-acoustic coupling mechanism. When the natural instabilities in the shear layer phase match with the acoustic waves generated from the impingement of the structures in the shear layer at the trailing edge of the cavity, high amplitude background noise and discrete cavity tones are generated in the form of high amplitude pressure fluctuations. Common examples of this phenomenon are aircraft landing gear openings, aircraft weapons bays, and engine air intakes. Unchecked cavity flow resonance can lead to weapon stores damage and incorrect deployment, reduction in lift, increase in drag, and structural fatigue. Initial research concentrated on using a compression driver as a synthetic jet type actuator to reduce acoustic resonance peaks, to operate the actuator at optimal forcing frequencies using reduced order modeling in order to shrink the peaks without triggering adjacent tones, and to develop logic based controls to damp pressure fluctuations within the system. The compression driver was ultimately limited by its frequency bandwidth and power output. The limited capabilities of the compression driver led to the development of the localized arc filament plasma actuator which is capable of high bandwidth and high amplitude actuation. The focus of this research was on the development of a high speed subsonic cavity flow facility and its control using localized arc filament plasma actuators (LAFPA). A cavity flow facility was designed and fabricated which allowed for the study of both baseline and forced cavity flows. The baseline flow characteristics were studied using flow visualization techniques in the form of particle image velocimetry (PIV) and schlieren photography, dynamic surface pressure measurements, and instantaneous and time-averaged dynamic pressure correlations to gain further understanding in cavity flow physics. Once the flow was sufficiently understood, LAFPAs were then used to force the flow into different modes or non-preferred frequencies in order to reduce the cavity tones or reduce the overall sound pressure level. Resonant, non-resonant, and multi-mode resonance are studied and actuated at various forcing frequencies, duty cycles, and modes. Furthermore, several different plasma actuator platforms were developed and tested to determine an optimal electrode arrangement during actuation.
Download or read book AIAA Journal written by American Institute of Aeronautics and Astronautics and published by . This book was released on 2007 with total page 990 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Active Control of Subsonic Cavity Flow Using Plasma Actuators written by Nathan George Kamps and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Due to the prevalence of stealth technology on increasing numbers of new aircraft, weapons and electronics that had previously been stored under the aircraft wings are now being stored in weapons bays inside the fuselage. When these bays are opened however, a damaging flow situation can arise to create high amplitude pressure fluctuations capable of damaging structures and systems of the aircraft and the weapons stored in the bay. Thus a major area of research at the Gas Dynamics and Turbulence Laboratory (GDTL) has been focused on the suppression of these pressure fluctuations. Previous results using active flow control and a compression driver showed good flow authority up to Mach 0.40, when actuator effectiveness was lost. Other research at the GDTL has focused on the use of localized arc filament plasma actuators (LAFPA's) to control flow instabilities in a high Mach number free jet. The focus of this research was to incorporate the plasma actuators in a cavity flow facility and investigate their effectiveness at suppressing the tone generated by flows of higher Mach numbers. The results presented in this paper detail the results of testing several different actuator configurations on Mach 0.69 flow over a shallow cavity.
Download or read book Simulation of the Localized Arc Filament Plasma Actuators for Jet Excitation written by Clifford A. Brown and published by . This book was released on 2010 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The concept of jet control by external forcing is not new. The first published demonstration of a jet responding to outside forces occurred in the mid-1800's. It was not, however, until the 1950's, with the advent of commercial jet aircraft, that scientific study of the subject greatly increased as researchers used external forcing to study the structure and noise sources present in a jet plume. Interest in active jet control continues today, particularly with the additional possibilities afforded by significant advances in measurement and simulation technology, even though it remains limited by the available jet actuators to relatively small, low Reynolds number jets that are of little similarity to the large, highly turbulent jets common in real world applications. However, the recently developed Localized Arc Filament Plasma Actuators (LAFPA) have the potential to expand active jet control research to include these larger, higher Reynolds number jets. The LAFPA have been used successfully to control a small-diameter, high-speed turbulent jet to achieve some plume mixing enhancement and limited noise mitigation. The system, however, must still be extended to a larger class of jets common in the real world and optimized for an application. This work addresses both of these issues. First, experiments are conducted to determine the impact of the LAFPA on a large-scale jet. A model of the LAFPA is then developed for use in the future CFD based studies of excited jets. The model performance is investigated using multiple CFD methodologies to determine the optimal combination of actuator model and CFD scheme for excited jet simulations. Ultimately, the model developed will be used by researchers in future simulations to optimize the actuator system for noise reduction, IR signature reduction, or to system scalability for deployment on larger jets in real-world applications."--Abstract.
Download or read book Advanced UAV Aerodynamics Flight Stability and Control written by Pascual Marqués and published by John Wiley & Sons. This book was released on 2017-07-11 with total page 799 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensively covers emerging aerospace technologies Advanced UAV aerodynamics, flight stability and control: Novel concepts, theory and applications presents emerging aerospace technologies in the rapidly growing field of unmanned aircraft engineering. Leading scientists, researchers and inventors describe the findings and innovations accomplished in current research programs and industry applications throughout the world. Topics included cover a wide range of new aerodynamics concepts and their applications for real world fixed-wing (airplanes), rotary wing (helicopter) and quad-rotor aircraft. The book begins with two introductory chapters that address fundamental principles of aerodynamics and flight stability and form a knowledge base for the student of Aerospace Engineering. The book then covers aerodynamics of fixed wing, rotary wing and hybrid unmanned aircraft, before introducing aspects of aircraft flight stability and control. Key features: Sound technical level and inclusion of high-quality experimental and numerical data. Direct application of the aerodynamic technologies and flight stability and control principles described in the book in the development of real-world novel unmanned aircraft concepts. Written by world-class academics, engineers, researchers and inventors from prestigious institutions and industry. The book provides up-to-date information in the field of Aerospace Engineering for university students and lecturers, aerodynamics researchers, aerospace engineers, aircraft designers and manufacturers.
