Download or read book Separation Control on High Angle of Attack Airfoil Using Plasma Actuators written by Martiqua L. Post and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High lift Airfoil Separation Control with Dielectric Barrier Discharge Plasma Actuators written by Jesse Little and published by . This book was released on 2010 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This work examines the performance of dielectric barrier discharge (DBD) plasma actuators for controlling separation from the leading edge and trailing edge flap shoulder of a supercritical high-lift airfoil. DBD plasma actuators driven by both typical AC voltages (AC-DBD) and more developmental nanosecond duration pulses (NS-DBD) are investigated. Characterization of the two actuators shows that very different behavior is created when exciting the plasma discharge using these two waveforms. The AC-DBD plasma actuator functions through electrohydrodynamic effects that introduce zero net mass, but nonzero net momentum into the flow. Conversely, the electrohydrodynamic effects of the NS-DBD are quite weak suggesting thermal effects from rapid localized heating by the plasma are responsible for control authority. The performance of both devices as separation control actuators is tested on a high-lift airfoil system. The AC-DBD is effective for controlling turbulent boundary layer separation from a deflected trailing edge flap between Reynolds numbers of 240,000 and 750,000. Momentum coefficients for the AC-DBD plasma actuator are generally an order of magnitude lower than those usually employed for such studies yet control authority is still realized through amplification of natural vortex shedding from the flap shoulder. The corresponding lift enhancement is primarily due to upstream effects from increased circulation around the entire model rather than full separated flow reattachment to the deflected flap surface. Lift enhancement via instability amplification is found to be relatively insensitive to changes in angle of attack provided that the separation location and underlying dynamics do not change. Control authority decreases with increasing Reynolds number and flap deflection highlighting the necessity for further optimization of AC-DBD plasma actuators for use in realistic takeoff and landing transport aircraft applications. As a whole, these findings compare favorably to studies on a similar high-lift platform using piezoelectric driven zero net mass flux actuation. The NS-DBD plasma actuator is ineffective for controlling separation from the deflected trailing edge flap. However, the device is found to be superior to the tested AC-DBD plasma actuators for controlling leading edge separation and rivals the performance of a passive droop by extending the stall angle by six degrees in the Reynolds number range 750,000-1,000,000. Detailed flow diagnostics show the NS-DBD plasma actuator functions as an active trip for pre-stall incidence angles and generates coherent spanwise vortices that entrain freestream momentum into the separated region at post-stall angles. These structures are generated across all surveyed frequencies, but optimal dimensionless frequencies for controlling separation are in the range four to six depending on the incidence angle. The contrasting performance of the NS-DBD plasma actuator at the leading and trailing edge in comparison to the AC-DBD is discussed and recommendations for future work are provided.
Download or read book Numerical Investigation of Plasma Actuator Configurations for Flow Separation Control at Multiple Angles of Attack written by Thomas Kelsey West and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The primary objective of the study presented in this thesis was to analyze the effectiveness of aerodynamic plasma actuators as a means of active flow control over a low speed airfoil at multiple angles of attack each corresponding to two different flow separation mechanisms (i.e., laminar separation bubble and turbulent flow separation at stall conditions). Detailed parametric studies based on steady and unsteady Navier-Stokes simulations, modified to include the body force term created by the plasma actuator, were performed for a NACA 0012 airfoil at a chord Reynolds number of 105. In particular, parametric studies were performed to investigate the influence of the number, the location, the imposed body force magnitude (power input) and steady vs. unsteady operation of plasma actuators on the flow control effectiveness. First, the effectiveness of plasma actuators was studied when applied to the airfoil at a relatively low angle of attack, which involved the development of a laminar separation bubble (LSB). Next, the effectiveness of plasma actuators was analyzed at a high angle of attack where the stall of the airfoil occurs with a fully turbulent flow assumption. The results show that plasma actuators can provide significant improvement in aerodynamic performance for the flow conditions considered in this study. For LSB control, as much as a 50% improvement in the lift to drag ratio was observed. Results also show that the same improvement can be achieved using an unsteady or multiple actuators, which can require as much as 75% less power compared to a single, steady actuator. For the stalled airfoil case, as much as a 700% improvement in L/D was observed from a single, steady actuator. Note that this was achieved using a power input eight times higher than what was used for LSB control. Also, unsteady and multiple actuator configurations do not provide the same enhancement as the single, steady actuators. This was found to be due to the nature of the turbulent separation (trailing edge separation) at the stall condition that occurs for the selected airfoil and Reynolds number"--Abstract, leaf iii
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 Control of Flow Separation from the Deflected Flap of a High lift Airfoil Using Multiple Dielectric Barrier Discharge DBD Plasma Actuators written by Kristine L. McElligott and published by . This book was released on 2010 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In current wing design, multiple flaps are incorporated into the trailing edge to allow mixing of high and low pressure sides to reduce flow separation. These flaps reduce the efficiency by adding weight and complexity to the aircraft. A single hinged flap would reduce these inefficiencies but is more susceptible to flow separation. Active flow control is a means by which the fluid flow over a body is deliberately altered and can be altered such that it becomes less likely to separate from the object. By energizing the flow, the degree of separation of the flow can be controlled, and this inherently controls lift. Dielectric barrier discharge (DBD) plasma actuators are a form of active flow control. These actuators are created by asymmetrically aligning two electrodes and adding a dielectric layer between the electrodes. When the electrodes are electrically connected, ionized air (plasma) travels from the exposed electrode towards the covered electrode. Collisions occur between the plasma and neutral air over the body, and momentum is transferred to the neutral air, effectively energizing it. The purpose of this study is to examine the lift enhancement and flow control authority that multiple DBD plasma actuators have on a high-lift airfoil when compared to the flow exhibited by non-controlled and single DBD plasma actuator controlled cases. Electrodes were mounted onto a simplified NASA Energy Efficient Transport airfoil near the flap. The airfoil was tested in a closed, recirculating wind tunnel operating at a Reynolds number of 240,000, 20° flap deflection angle and 0° degree angle of incidence. The actuators were independently powered in order to determine the most effective input parameters. Using multiple actuators operated in-phase has increased the lift and has delayed flow separation on the trailing edge flap when compared to baseline and single actuation cases.
Download or read book Physics and Control of Flow Over a Thin Airfoil Using Nanosecond Pulse DBD Actuators written by Ghasemi Esfahani Ata and published by . This book was released on 2017 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flow separation leading to stall imposes considerable performance penalties on lifting surfaces. Limitations in flight envelope and loss of control are among the chief reasons for the interest in the aeronautical research community for better understanding of this phenomenon. Modern flow control techniques explored in this work can potentially alleviate the performance penalties due to flow separation. Experiments were designed to investigate excitation of flow over an airfoil with leading edge separation at a post-stall angle of attack with nanosecond pulse dielectric barrier discharge actuators. The subject airfoil is designed with a small radius of curvature that potentially challenges the task of flow control as more centrifugal acceleration around leading is required to successfully reattach the flow. The Reynolds number based on the chord was fixed at 5·105, corresponding to a freestream flow of approximately 37 m/s. An angle of attack of 19° was used and a single plasma actuator was mounted near the leading edge of the airfoil. Fully separated flow on the suction side extended well beyond the airfoil with naturally shed vortices generated at a Strouhal number of 0.60. Excitation at very low to moderate (~1) Strouhal numbers at the leading edge generated organized coherent structures in the shear layer over the separated region with a shedding Strouhal number corresponding to that of the excitation, synchronizing the vortex shedding from leading and trailing edges. Excitation around the shedding Strouhal number promoted vortex merging while excitation at higher Strouhal numbers resulted in smaller, weaker structures that quickly developed and disintegrate over the airfoil. The primary mechanism of control is the excitation of instabilities associated with the vortices shed from leading edge. The excitation generates coherent large-scale structures that entrain high-momentum fluid into the separation region to reduce the separation and/or accelerate the flow over the airfoil and to modify the lift and drag properties. The baseline showed some spanwise non-uniformity both on and off the surface. Excitation at low Strouhal numbers (0.3
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.
Download or read book Airfoil Separation Control with Plasma Actuators written by Shawn Fleming and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Separation Control Using Plasma Actuators Experimental Studies of Plasma Actuator Performance written by DartKen Poon and published by . This book was released on 2011 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Airfoil Leading and Trailing Edge Separation Control Using SDBD Plasma Actuators written by Christopher L. Kelley and published by . This book was released on 2013 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Enhanced Design of Turbo Jet LPT by Separation Control Using Phased Plasma Actuators written by and published by . This book was released on 2003 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Separation Control Using Plasma Actuators in a High Pressure Bend written by Michael J. Arthur and published by . This book was released on 2014 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Leading edge Flow Separation Control Over a NACA 0012 Aerofoil with DBD Plasma Actuators written by Longfei Song and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Instability and Control of Massively Separated Flows written by Vassilis Theofilis and published by Springer. This book was released on 2015-01-03 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the outcome of the international meeting on instability, control and noise generated by massive flow separation that was organized at the Monash Center, in Prato, Italy, September 4-6, 2013. The meeting served as the final review of the EU-FP7 Instability and Control of Massively Separated Flows Marie Curie travel grant and was supported by the European Office of Aerospace Research and Development. Fifty leading specialists from twelve countries reviewed the progress made since the 50s of the last century and discussed modern analysis techniques, advanced experimental flow diagnostics and recent developments in active flow control techniques from the incompressible to the hypersonic regime. Applications involving massive flow separation and associated instability and noise generation mechanisms of interest to the aeronautical, naval and automotive industries have been addressed from a theoretical, numerical or experimental point of view, making this book a unique source containing the state-of-the-art in separated flow instability and its control.
Download or read book Active Flow Control written by Rudibert King and published by Springer Science & Business Media. This book was released on 2007-08-29 with total page 441 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains contributions presented at the Active Flow Control 2006 conference, held September 2006, at the Technische Universität Berlin, Germany. It contains a well balanced combination of theoretical and experimental state-of-the-art results of Active Flow Control. Coverage combines new developments in actuator technology, sensing, robust and optimal open- and closed-loop control and model reduction for control.
Download or read book Wind Tunnels and Experimental Fluid Dynamics Research written by Jorge Colman Lerner and published by BoD – Books on Demand. This book was released on 2011-07-27 with total page 728 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book "Wind Tunnels and Experimental Fluid Dynamics Research" is comprised of 33 chapters divided in five sections. The first 12 chapters discuss wind tunnel facilities and experiments in incompressible flow, while the next seven chapters deal with building dynamics, flow control and fluid mechanics. Third section of the book is dedicated to chapters discussing aerodynamic field measurements and real full scale analysis (chapters 20-22). Chapters in the last two sections deal with turbulent structure analysis (chapters 23-25) and wind tunnels in compressible flow (chapters 26-33). Contributions from a large number of international experts make this publication a highly valuable resource in wind tunnels and fluid dynamics field of research.
