Download or read book An Experimental Study of a Pulsed DC Discharge Plasma Flow Control Actuator written by Jennifer D. Wall and published by . This book was released on 2006 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Study of a Pulsed DC Plasma Flow Control Actuator written by and published by . This book was released on 2006 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experiment on the effects of a pulsed DC plasma actuator on a separated flow in a low speed wind tunnel was conducted. The actuator consisted of two asymmetric copper electrodes oriented normal to the flow separated by a dielectric barrier and mounted on a flat plate in the center of the tunnel. A contoured insert was constructed and used to create an adverse pressure gradient in the test section comparable to a Pak-B low pressure turbine blade distribution. Suction was applied from the upper wall to induce separation along the flat plate over the electrodes. The DC power supply was kept constant at 8.5 kV and power was regulated through a high voltage fast transistor switch. The pulse width of the switch remained at 250 ns with the frequency ranging from 25 to 100 Hz. All studies were conducted at a Reynolds number of 30,000 to simulate takeoff and other low speed conditions. It was found that the DC pulsed plasma actuator could reattach the flow but not consistently at these conditions. Furthermore no evidence was found to indicate that coherent vortical structures are responsible for reenergizing the boundary layer and controlling separation.
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 Experimental Investigation of Pulsed DBD Plasma Actuators for Aerodynamic Flow Control written by Philip Peschke and published by . This book was released on 2014 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Study on Surface Dielectric Barrier Discharge Plasma Actuator with Different Encapsulated Electrode Widths for Airflow Control at Atmospheric Pressure supported by National Natural Science Foundation of China No 11175037 National Natural Science Foundation for Young Scientists of China No 11305017 and Special Fund for Theoretical Physics No 11247239 written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: The surface dielectric barrier discharge (SDBD) plasma actuator has shown great promise as an aerodynamic flow control device. In this paper, the encapsulated electrode width of a SDBD actuator is changed to study the airflow acceleration behavior. The effects of encapsulated electrode width on the actuator performance are experimentally investigated by measuring the dielectric layer surface potential, time-averaged ionic wind velocity and thrust force. Experimental results show that the airflow velocity and thrust force increase with the encapsulated electrode width. The results can be attributed to the distinct plasma distribution at different encapsulated electrode widths.
Download or read book Investigation of Magnetohydrodynamic Plasma Actuators for Aerodynamic Flow Control written by Brent Joel Pafford and published by . This book was released on 2013 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the analysis, fabrication and testing of a novel magnetohydrodynamic plasma actuator for aerodynamic flow control, specifically, retreating blade stall. A magnetohydrodynamic plasma actuator is comprised of two parallel rail electrodes embedded chord-wise on the upper surface of an airfoil. A pulse forming network generates a low-voltage, high-current repetitive pulsed arc. Self-induced electromagnetic fields force the pulsed arc along the length of the rail electrodes at high velocities, transferring momentum to the surrounding air, creating a high-velocity pulsed air wall jet. A systematic experimental investigation of the effect of plasma actuators on the surrounding air is conducted in stagnant air conditions to gain an understanding of the physical characteristics. These characteristics include voltage and current measurements, pulsed arc velocity measurements, and high speed video imaging. The results show typical pulsed arc velocities of about 100 m/s can be induced with discharge energies of about 300 J per pulse. Additional experimental studies are conducted to quantify the performance of the pulsed arc for potential use in subsonic flow control applications. To gain an estimate of the momentum transferred from the pulsed arc to the surrounding air the plasma actuator is placed in a subsonic open-circuit wind tunnel at a Reynolds number of 4.5 x 105. The induced velocity of the pulsed wall jet is measured using a Laser Doppler Anemometer. The measurements show that the pulsed arc creates a high-velocity pulsed wall jet that extends 40 mm above the airfoils surface and has an induced velocity of 15 m/s greater than the unaltered air flow over the airfoil, with peak velocities of 32 m/s. The magnetohydrodynamic plasma actuator proved to induce velocities an order of magnitude greater than the velocities attained by current state-of-the-art plasma actuators. Moreover, the RailPAc is found to posses the potential for alleviation of retreating blade stall. Future work will include experiments to gain a detailed understanding of the improvements to the static stall angle, the optimal actuator geometry, excitation duty cycle, magnetic field augmentation, and behavior of the plasma armature at high Mach/Reynolds numbers. Particle Image Velocimetry (PIV) will be utilized to improve the induced flow velocity measurements acquired with the LDA.
Download or read book Using Plasmas for High speed Flow Control and Combustion Control written by Saurabh Keshav and published by . This book was released on 2008 with total page 247 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Experiments on characterization of Localized Arc Filament Plasma Actuators used for high-speed flow control, as well as experimental studies of chemiluminescence and chemi-ionization for flame emission and combustion control have been discussed. Pulsed DC and pulsed RF actuator discharge power measurements and plasma temperature measurements demonstrated that rapid localized heating, at a rate of 1000 degrees C / 10 us, can be achieved at low time-averaged actuator powers, 10-20 W for 10% duty cycle. Kinetic modeling of a pulsed arc filament demonstrated formation of strong compression waves due to rapid localized heating, which have also been detected in the experiments. The effect of electrons in chemi-ionized supersonic flows of combustion products on flow emission is studied experimentally. For this, a stable ethylene/oxygen/argon flame is sustained in a combustion chamber at a stagnation pressure of P0=1 atm. Electron density in M=3 flow of combustion products has been measured using Thomson discharge. The results show that nearly all electrons can be removed from the flow by applying a moderate transverse electric field. No effect of electron removal on CH and C2 emission from the flow has been detected. Also, electron removal did not affect NO [beta] band and CN violet band emission when nitric oxide was injected into the combustion product flow. Chemi-ionization current measured in the supersonic flows of combustion products has been used for feedback combustion control. The experiments showed that time-resolved chemi-ionization current is in good correlation with the visible emission (CH and C2 bands) in the combustor at unstable combustion conditions, and is nearly proportional to the equivalence ratio at stable combustion conditions. Chemi-ionization current signal from the combustion product flow has been used to control an actuator valve in the fuel delivery line and to maintain the equivalence ratio in the combustor at the desired level.
Download or read book Fundamental Physics and Application of Plasma Actuators for High speed Flows written by Eli S. Lazar and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this dissertation, a detailed investigation is given discussing three plasma-based flow control methods. These methods included plasma generated by laser energy, microwaves, and electric arc. The plasma generated by laser energy was also applied to a sonic transverse jet in a supersonic cross flow. Lastly, the particle image velocimetry diagnostic was considered and a technique developed to evaluate measurement uncertainty and using experimental velocity data to solve for density from the continuity equation. In the laser-spark system, the effect of ambient pressure in the range of 0.1 to 1.0 atm and wavelength (266 nm and 532 nm) on the size, temperature, electron number density, and fraction of laser energy absorbed in a laser-induced plasma in air has been conducted. The plasma was generated by using optics to focus the laser energy. The focused laser pulse resulted in the induced optical breakdown of air, creating a plasma to perturb the flow field. As pressure or wavelength are reduced, the size of the plasma, its electron number density, and the fraction of incident laser energy that is absorbed are all found to decrease significantly. For the plasma generated by microwaves, the feasibility of using the system for flow control was demonstrated at pressures ranging from 0.05 atm to 1 atm and for pulsing frequencies between 400 Hz to 10 kHz. The setup was based on a quarter-wave coaxial resonator being operated with a microwave frequency of 2.45 GHz. Analysis of reflected power measurements suggested that the microwave energy could be best coupled into the resonator by using a small inductive loop, where the geometry can be experimentally optimized. The plasma was first characterized by recording images of the emission and taking temporal emission waveform profiles. Tests were conducted in quiescent air and analyzed with schlieren photography to determine the effectiveness of a plasma pulse to produce an instantaneous flow perturbation. Examination of phase averaged schlieren images revealed that a blast was produced by the emission and could be used to alter a flow field. The emission was also thermally characterized through emission spectroscopy measurements where the vibrational and rotational temperatures of the plasma were determined. The last system considered was a localized arc filament plasma actuator, or LAFPA-type device. The system creates electric arcs by generating electric fields in the range of 20 kV/cm between two pin-type electrodes. The potential of the actuator to influence surrounding quiescent flow was investigated using emission imaging, schlieren imaging, current and voltage probes, particle image velocimetry (PIV), and emission spectroscopy. The schlieren imaging revealed a potential to cause blast 0́−Mach0́+ waves and a synthetic jet with controllable directionality dependent on cavity orientation. The electric measurements revealed that, in order to increase the power discharged by the plasma, the electrode separation will only aid mildly and that an optimum plasma current exists (between 300-400 mA for the tested parameter space). The PIV data were acquired for various actuation frequencies and showed a trend between discharge frequency and maximum induced jet velocity. Finally, the emission spectroscopy data were acquired for four different cases: two electrode separations and two plasma currents. For each of the four conditions tested, the spectrum fit very well to a thermal distribution for early times in the emission. However, at later times in the emission, the spectrum no longer matched that of the second positive system under optically thick conditions for any combination of rotational and vibrational temperatures. Using the plasma generated by laser energy, an experimental investigation of flow control on a sonic underexpanded jet injected normally into a Mach 2.45 crossflow is reported. The jet exit geometry was circular and was operated at a jet-to-crossflow momentum flux ratio of 1.7. The unperturbed flow field was analyzed with schlieren imaging, PIV velocity data, surface oil flow visualizations, and pressure sensitive paint measurements. As a means of excitation to the flow field, the plasma energy was focused in the center of the jet exit at three different vertical locations. The perturbed resulting flow field was analyzed with schlieren photography and particle image velocimetry. Analysis of phase averaged schlieren images suggested that the resulting blast wave from the laser pulse disrupted the structure of the barrel shock and Mach disk. The two-component velocity field data revealed that the excitation pulse also caused a perturbation to the jet shear layer and induced the formation of vortices that convect downstream. Finally, additional techniques were developed for the PIV diagnostics. First, while PIV is an established experimental technique for determining a velocity field, quantifying the uncertainty related with this method remains a challenging task. To this end, four sources of uncertainty are assessed: equipment, particle lag, sampling size, and processing algorithm. An example uncertainty analysis is conducted for a transverse sonic jet injected into a supersonic crossflow. However, the analysis is not specific to the example flow field and may be generally applied to any mean velocity field. Secondly, using the velocity data from PIV, a technique was developed to solve for density from the continuity equation over the entire flow field. The technique is validated using data from CFD simulations and demonstrated for experimental data for two flow fields.
Download or read book Active Boundary Layer Control written by Andrew T. Myers and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Actuators written by Constantin Volosencu and published by BoD – Books on Demand. This book was released on 2018-07-11 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book promotes new research results in the field of modern actuators and their applications. New coverage of dielectric barrier discharge plasma actuators, polymeric microgripper based on the cascaded V-shaped electrothermal actuators, ionic polymer actuators, wideband actuators and energy harvesters, electromagnetic actuators and shape memory alloy actuators are comprehended. The book is structured in four sections: design, fabrication and simulation; control systems; medical applications and fault detection. Seven chapters are published following a rigorous selection process. In the first section, a study carried out to investigate experimentally and by numerical simulations a microscale plasma actuator; the design, fabrication, numerical simulations, and experimental investigations of a polymeric microgripper designed using the cascaded V-shaped electrothermal actuators; a review of the development of ionic polymer actuator with introduction of two kinds of typical polymer actuators - ionic polymer-metal composites and bucky gel actuator - with their basic principle and fabrication process and typical applications and a methodology of designing and testing wideband actuators and energy harvesters, treated as one mechanical resonator, with a discussion on shock harvester, resonant harvester and energy transmission system, are presented. The second section has a chapter dedicated to modeling, system identification and control of electromagnetic actuators with main focus on the actuators used in magnetic levitation, in fuel injection systems and in variable valve timing. The third section presents a study focused on quantifying the decline in tactile sensation associated with diabetic neuropathy and developed a measurement device that used a thin-shaped memory alloy wire as the actuator. The fourth section includes a chapter presenting a two-level fault diagnosis and root-cause analysis scheme for a class of interconnected invertible dynamic systems, which aims at detecting and identifying actuator fault and causes.
Download or read book Active Turbulent Boundary Layer Control written by Alan H. Duong and published by . This book was released on 2019 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computational Investigation of Plasma Actuator as an Active Flow Control Strategy of Laminar Separation Bubbles written by Justin Roger Aholt and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "A parametric computational study designed to examine the plausibility of an external body force generated by active means, such as a plasma actuator, as a means of controlling a Laminar Separation Bubble (LSB) over an airfoil at low Reynolds numbers was conducted. Computational Fluid Dynamics (CFD) was employed to characterize the effect that a body force, localized to a small region tangent to the airfoil surface, might have on an LSB. In this study, the effects of altering the strength and location of the "actuator" on the size and location of the LSB and on the aerodynamic performance of the airfoil were observed. In a separate investigation, the effects of operating an actuator in a "burst" mode are investigated, where the effects of pulsing frequency and duty cycle are examined to determine whether further performance enhancements can be achieved via such means. It was found that the body force, when properly located and with sufficient magnitude, could effectively eliminate the LSB. Additionally, it was found that by eliminating the LSB, the aerodynamic efficiency of the airfoil could be improved by as much as 60%. Thus, it was determined that such a system may indeed be an effective measure of reducing or eliminating the negative effects associated with LSBs at low Reynolds numbers. Additionally, pulsed operation of the actuator was found to enhance effectiveness by as much as 20% over a power-equivalent steady actuator. These results indicate that such a control strategy may be an excellent candidate for future experimental research regarding this topic"--Abstract, leaf iii
Download or read book A Theoretical and Experimental Study of Piezoelectric Unimorph Actuators for Active Flow Control written by Jose Mathew and published by . This book was released on 2002 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Experimental Parameter Studies of Various Plasma Actuator Concepts for Active Flow Control at Moderate Reynolds Numbers written by Pawel Piotrowski 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 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:
