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Numerical Study On Active Flow Control Using Synthetic Jet Actuators Over A Naca 4421 Airfoil
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Book Synopsis Numerical Study on Active Flow Control Using Synthetic Jet Actuators Over a NACA 4421 Airfoil by : Xavier Guerrero Pich
Download or read book Numerical Study on Active Flow Control Using Synthetic Jet Actuators Over a NACA 4421 Airfoil written by Xavier Guerrero Pich and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study is focused on evaluating the effects of using a Zero Net Mass Flux (ZNMF) actuator on a NACA 4421 airfoil for active flow control. First part of the study presents the fundamentals of boundary layer and a study of the available devices which are more used for flow control, focusing on the ZNMF. The steps for creating the mesh to perform numerical simulations of the airfoil are explained, and the results of the CFD simulations are compared with experimental data as a vaseline balidation. In the secord part, the ZNMF is studied in order to set the parameters of the actuator and to simulate its effect on CFD, and moreover the numerical simulations of the airfoil with the ZNMF set up are performed and the results are evaluated. The evaluation will show the most optimum parameters for the actuator, as well as the effects that the ZNMF has on the airfoil's behaviour.
Book Synopsis Numerical Study of Active Flow Control Using Synthetic Jets by : Jeremy Dennis Roth
Download or read book Numerical Study of Active Flow Control Using Synthetic Jets written by Jeremy Dennis Roth and published by . This book was released on 2003 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Active Flow Control (AFC) using synthetic jets (SJ's) is numerically simulated for several simple aerodynamic shapes at high Reynolds numbers using the Computational Fluid Dynamics (CFD) computer program, CFL3D. AFC is the manipulation of a flow field around a given body in a fluid. AFC is used to improve the resulting flow characteristics bodies produce in regimes of flow separation which result from large pressure gradients. In the AFC device (SJ's) used in this study fluid is periodically displaced from a cavity with an orifice. A SJ relies on the entertainment of the local ambient fluid mass external to the device. Therefore, with the use of SJ's a significant decrease in complexity and weight is possible as compared to other more traditional AFC devices involving mass transfer. The objective of this study is to illustrate how AFC in the form of SJ's can be utilized to enhance the aerodynamic performance of simple aerodynamic shapes such as a circular cylinder, airfoil, and three-dimensional wing in flow conditions which result in boundary layer separation. A flat plate with zero pressure gradient is also analyzed in order to determine the effect of SJ's in the absence of boundary layer separation. In order to provide a fundamental understanding of the enhanced aerodynamic performance an additional investigation of classical boundary layer parameters is performed. Computational results are then presented for the bodies of interest with no AFC and validated with experimental results where available. Secondly, results for the numerical investigations with AFC are presented. The results of this study demonstrate that SJ's enhance the aerodynamic characteristics of the configurations and provide more favorable conditions in those regimes of the flow that are normally highly separated. The present study also revealed that a three-dimensional flow is quite similar in character to two-dimensional flows in the presence of SJ's. Overall, this study illustrates SJ's are effective in boundary layer control, and can be used to improve the aerodynamics of aerospace vehicles.
Book Synopsis Numerical Studies of the Application of Active Flow Control to Subsonic and Transonic Airfoil Flows Using a Synthetic Jet Actuator by : Jose L. Vadillo
Download or read book Numerical Studies of the Application of Active Flow Control to Subsonic and Transonic Airfoil Flows Using a Synthetic Jet Actuator written by Jose L. Vadillo and published by . This book was released on 2005 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Advances in Effective Flow Separation Control for Aircraft Drag Reduction by : Ning Qin
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.
Book Synopsis Numerical Study of Virtual Aerodynamic Shape Modification of an Airfoil Using a Synthetic Jet Actuator by : Jose L. Vadillo
Download or read book Numerical Study of Virtual Aerodynamic Shape Modification of an Airfoil Using a Synthetic Jet Actuator written by Jose L. Vadillo and published by . This book was released on 2002 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthetic Jet Flow Control of Two-dimensional NACA 65(1)-412 Airfoil Flow with Finite-Time Lyapunov Exponent Analysis of Lagrangian Coherent Structures by :
Download or read book Synthetic Jet Flow Control of Two-dimensional NACA 65(1)-412 Airfoil Flow with Finite-Time Lyapunov Exponent Analysis of Lagrangian Coherent Structures written by and published by . This book was released on 2016 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: Synthetic jet (SJ) control of a low-Reynolds number, unsteady, compressible, viscous flow over a NACA 65-(1)412 airfoil, typical for unmanned air vehicles and gas turbines, has been investigated computationally. A particular focus was placed in the development and control of Lagrangian Coherent Structures (LCS) and the associated Finite-Time Lyapunov Exponent (FTLE) fields. The FTLE fields quantitatively measure of the repulsion rate in forward-time and the attraction rate in backward-time, and provide a unique perspective on effective flow control. A Discontinuous-Galerkin (DG) methods, high-fidelity Navier-Stokes solver performs direct numerical simulation (DNS) of the airfoil flow. Three SJ control strategies have been investigated: immediately downstream of flow separation, normal to the separated shear layer; near the leading edge, normal to the airfoil suction side; near the trailing edge, normal to the airfoil pressure side. A finite difference algorithm computes the FTLE from DNS velocity data. A baseline flow without SJ control is compared to SJ actuated flows. The baseline flow forms a regular, time-periodic, asymmetric von Karman vortex street in the wake. The SJ downstream of flow separation increases recirculation region vorticity and reduces the effective angle of attack. This decreases the time-averaged lift by 2:98% and increases the time-averaged drag by 5:21%. The leading edge SJ produces small vortices that deflect the shear layer downwards, and decreases the effective angle of attack. This reduces the time-averaged lift by 1:80%, and the time-averaged drag by 1:84%. The trailing edge SJ produces perturbations that add to pressure side vortices without affecting global flow characteristics. The time-averaged lift decreases by 0:47%, and the time-averaged drag increases by 0:20%. For all SJ cases, the aerodynamic performance is much more dependent on changes to the pressure distribution than changes to the skin friction distribution. No proposed SJ case improved aerodynamic performance. Some desirable SJ control effects were observed, which may be isolated in a future study by optimizing SJ parameters. Stably increasing recirculation region vorticity, and maintaining or increasing the effective angle of attack are desirable for lift increase, while deflecting the separated shear layer downward is desirable for drag reduction.
Book Synopsis Study of the Boundary Layer Flow Control Using Synthetic Jets by Means of Spectro-consistent Discretizations by : David Duran Perez
Download or read book Study of the Boundary Layer Flow Control Using Synthetic Jets by Means of Spectro-consistent Discretizations written by David Duran Perez and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents a study of the interaction of AFC (specifically, synthetic jets) with the laminar boundary layer of a NACA 0012 airfoil. First of all, in order to understand the phenomenology of Navier-Stokes equations, a spectro-consistent Computational Fluid Dynamics (CFD) code has been developed from scratch. By using a spectro-consistent discretization, the fundamental symmetry properties of the underlying differential operators are preserved. This code also helps to understand how the energy is transported from big to small scales. After solving a paradigmatic problem (TGV) using the aforementioned code, a mature CFD code (Alya) is used to simulate the flow around the NACA 0012 airfoil. Alya software also uses a spectro-consistent code but in Finite Element Method (FEM). Once the reference cases are solved for different angles of attack, a boundary condition representing an idealized synthetic jet is implemented. A systematic parametrization of the synthetic jet has been performed in order to assess the level of flow control in the boundary layer. Results demonstrate that, by selecting a correct combination of actuator frequency and momentum coefficient, the lift coefficient increases while the drag coefficient decreases producing a better lift-to-drag ratio. This aerodynamic improvement implies that a better circulation control is achieved, less noise is produced and less fuel consumption is required. It is also worth noting that, for high angles of attack, it is necessary to perform 3D flow simulations in order to capture the entire physics of the problem.
Book Synopsis Numerical Analyses of Passive and Active Flow Control Over a Micro Air Vehicle with an Optimized Airfoil by : Komal Kantilal Gada
Download or read book Numerical Analyses of Passive and Active Flow Control Over a Micro Air Vehicle with an Optimized Airfoil written by Komal Kantilal Gada and published by . This book was released on 2015 with total page 47 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Numerical investigations of an optimized thin airfoil with a passive and an active flow control device (riblets and rotary cylinder) have been performed. The objectives of the thesis were to investigate the tip vortices reduction using riblets and decrease in flow separation, using a rotary cylinder for improved lift-to-drag ratio. The investigations has application potentials in improving performances of Micro Air Vehicles (MAVs). The airfoil has a chord length of 19.66 cm and a span of 25 cm. with the free stream mean velocity was set at 20 m/s. The Reynolds number was calculated as 3 x 104. Investigations with base model of the airfoil have shown flow separation at approximately 85% chord length at an angle of attack of 17 degrees. For investigation using passive flow control device, i.e. riblets, investigations were performed for different radial sizes but at a fixed location. It was found that with 1 mm radial size riblet, the tip vortices were reduced by approximately 95%, as compared to the baseline model. Although negligible lift-to-drag improvement was seen, a faster dissipation rate in turbulent kinetic energy was observed. Furthermore, investigations were carried out using the active flow control device. The rotary cylinder with a 0.51 cm in diameter was placed slightly downstream of the location of flow separation, i.e. at x/c = 0.848. Investigations were performed at different cylinder's rotations, corresponding to different tangential velocities of being higher than, equal to and less than the free stream mean velocity. Results have shown approximately 10% improvement in lift to drag ratio when the tangential velocity is near the free stream mean velocity. Further investigation may include usage of the riblets and the rotary cylinder combined, to increase the stability as well as the lift-to-drag ratio of the MAVs.
Book Synopsis Active Flow Control of Subsonic Flow in an Adverse Pressure Gradient Using Synthetic Jets and Passive Micro Flow Control Devices by : Michael E. Denn
Download or read book Active Flow Control of Subsonic Flow in an Adverse Pressure Gradient Using Synthetic Jets and Passive Micro Flow Control Devices written by Michael E. Denn and published by . This book was released on 2013 with total page 153 pages. Available in PDF, EPUB and Kindle. Book excerpt: Several recent studies have shown the advantages of active and/or passive flow control devices for boundary layer flow modification. Many current and future proposed air vehicles have very short or offset diffusers in order to save vehicle weight and create more optimal vehicle/engine integration. Such short coupled diffusers generally result in boundary layer separation and loss of pressure recovery which reduces engine performance and in some cases may cause engine stall. Deployment of flow control devices can alleviate this problem to a large extent; however, almost all active flow control devices have some energy penalty associated with their inclusion. One potential low penalty approach for enhancing the diffuser performance is to combine the passive flow control elements such as micro-ramps with active flow control devices such as synthetic jets to achieve higher control authority. The goal of this dissertation is twofold. The first objective is to assess the ability of CFD with URANS turbulence models to accurately capture the effects of the synthetic jets and micro-ramps on boundary layer flow. This is accomplished by performing numerical simulations replicating several experimental test cases conducted at Georgia Institute of Technology under the NASA funded Inlet Flow Control and Prediction Technologies Program, and comparing the simulation results with experimental data. The second objective is to run an expanded CFD matrix of numerical simulations by varying various geometric and other flow control parameters of micro-ramps and synthetic jets to determine how passive and active control devices interact with each other in increasing and/or decreasing the control authority and determine their influence on modification of boundary layer flow. The boundary layer shape factor is used as a figure of merit for determining the boundary layer flow quality/modification and its tendency towards separation. It is found by a large number of numerical experiments and the analysis of simulation data that a flow control device's influence on boundary layer quality is a function of three factors: (1) the strength of the longitudinal vortex emanating from the flow control device or devices, (2) the height of the vortex core above the surface and, when a synthetic jet is present, (3) the momentum added to the boundary layer flow.
Book Synopsis Lifting Surfaces Aeroelastic Experimental Investigations and Implementation of Active Flow Control Using Synthetic Jet Actuators by : Keegan S. O'Donnell
Download or read book Lifting Surfaces Aeroelastic Experimental Investigations and Implementation of Active Flow Control Using Synthetic Jet Actuators written by Keegan S. O'Donnell and published by . This book was released on 2008 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Investigation of Synthetic Jet Flow Control Parameters for the Mitigation of Laminar Boundary Layer Separation by : Mark Alexander Feero
Download or read book Investigation of Synthetic Jet Flow Control Parameters for the Mitigation of Laminar Boundary Layer Separation written by Mark Alexander Feero and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study was performed to elucidate the effects of forcing parameters on the mitigation of boundary layer separation on an airfoil at low Reynolds number. Post- stall flow at a Reynolds number of 100,000 and angle-of-attack 12 degrees on a NACA 0025 airfoil served as the baseline for control with a synthetic jet actuator. This baseline flow is characterized by two dominant instabilities: the large scale vortex shedding in the wake of the airfoil, and the roll-up of vortices in the separated shear layer. The forcing parameters that were investigated were the blowing ratio, excitation frequency, and the chordwise forcing location. The results concerning the effects on aerodynamic performance showed that for both drag reduction and lift increase, the benefits of control saturated with increasing blow- ing ratio. Initial improvements to lift and drag were due to the formation of a laminar separation bubble, followed by fully attached flow once a threshold blowing ratio was met. Positioning the slot at the most upstream location resulted in the lowest thresh- old blowing ratio and produced the largest lift-to-drag ratios. A monotonic increase in threshold blowing ratio and decrease in lift-to-drag was observed as the slot location moved downstream. It was also found that while forcing at a frequency corresponding to the wake instability led to maximum lift increase, forcing in the range of the separated shear layer instability led to maximum drag reduction. High-frequency forcing, where the time scales of control are much smaller than those of the flow, was found to be least effective for improving performance. The controlled flow dynamics revealed the presence of large vortices passing over the suction surface and highly unsteady flow when forcing at the wake instability frequency, whereas forcing in the range of the shear layer instability led to the production of a larger number of much smaller vortices. The latter case led to a thinner boundary layer in the time-averaged sense. Extraction of coherent and turbulent velocity fluctuations showed that the controlled flow was steady in time with high-frequency forcing.
Book Synopsis The Effectiveness of Actuators Used in Active Flow Control by : Hermann F. Fasel
Download or read book The Effectiveness of Actuators Used in Active Flow Control written by Hermann F. Fasel and published by . This book was released on 2002 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Unsteady Aerodynamics of Airfoils and Characterization and Modeling of Axisymmetric Synthetic Jets by : Xi Xia
Download or read book Unsteady Aerodynamics of Airfoils and Characterization and Modeling of Axisymmetric Synthetic Jets written by Xi Xia and published by . This book was released on 2018-11-29 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This thesis has two main parts. The aerodynamic part is motivated by the interest in unveiling the flying secrets of natural fliers, e.g. birds and insects. The understandings will provide insights in the design and control of micro air vehicles (MAVs) for improved aerodynamic performance. The second part of the thesis focuses on the study of synthetic jets for aerodynamic flow control over MAVs. This is motivated by the promising effects of synthetic jets in enhancing mixing and controlling flow separation. The thesis starts with the unsteady aerodynamic modeling of a flat plate based on the Joukowski transformation and vortex method. The analytical solution includes both translational and rotational motions of the flat plate. The force calculation suggests that the lift generation caused by a stabilized leading edge vortex is a combined effect of the motions of both leading-edge and trailing-edge vortices. To extend this model to an arbitrarily-shaped airfoil, the wall boundary condition on the airfoil is enforced by introducing a bound vortex sheet at the location of the airfoil boundary. Furthermore, an analytical vortex-sheet formation condition is proposed to accurately evolve the wake vortices, and is based on the conservation laws of mass and momentum as well as Kelvin's circulation theorem. This condition resolves the paradox of the Giesing-Maskell model, which does not recover the steady-state Kutta condition. The thesis continues with an investigation of synthetic jets in a quiescent environment. An effective-eddy-viscosity concept is adopted to provide a unified modeling approach for the entrainment and mixing of any round jet, continuous or synthetic. The experimental study is focused on characterizing the spreading and decay features in the transitional region and far field of synthetic jets. The far-field momentum flux of a synthetic jet is modeled by calculating the hydrodynamic impulse of the vortical structure formed in the near field. Synthetic jets issuing into a crossflow are also studied and a self-similar model is developed for the trajectory and velocity of the midplane flow field. It is found that the crossflow velocity is enhanced in the near field due to the induced effect of the tilted vortex rings. This finding provides an auxiliary explanation for the mechanism of a synthetic jet in flow-separation control. Dissertation Discovery Company and University of Florida are dedicated to making scholarly works more discoverable and accessible throughout the world. This dissertation, "Unsteady Aerodynamics of Airfoils and Characterization and Modeling of Axisymmetric Synthetic Jets" by Xi Xia, was obtained from University of Florida and is being sold with permission from the author. A digital copy of this work may also be found in the university's institutional repository, IR@UF. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation.
Book Synopsis Active Flow Control in Aerodynamic Applications by : Pol Gil Aiguasenosa
Download or read book Active Flow Control in Aerodynamic Applications written by Pol Gil Aiguasenosa and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of this thesis is to determine the e ect of Active Flow Control ( AFC from now), studying, analyzing the behavior of airfoil and afterwards, implementing AFC and evaluate its impact on aerodynamic performance. The case characteristics are a 2D airfoil NACA 2412 computed at Re = 5000, angle of attack 20o and viscid incompressible ow. The objective of AFC is to retard the boundary layer detachment in order to reduce the amplitude of the vortex shedding created at the wake and reduce the induced drag and nally reduce drag e ect in comparison with the previous and standard studied case without AFC. Many parameters of AFC are involved in results: blowing, suction or sinusoidal behavior, amplitude of the AFC region, location implementation, magnitude or energy phenomena requested, etc. This study has been able to study limited cases due to computation cost reasons. But applying several hypothesis, the study has been able to extract conclusions. Computations are performed using no model turbulence trying to recreate the Direct Numerical Simulation ( DNS from now) concept although it can not be de ned as DNS properly due to this is a 2D case and required y+ standards can not be reached for computational cost reasons. This case is developed under a laminar regime due to low Reynolds number. The low Reynolds number is high is the rst cell requested is for the same y+ requested. The reason why this case is based on low Reynolds number is due to using Reynolds-Averaged Navier-Stokes ( RANS from now) equations with no turbulence model trying to reproduce DNS concept is because low y+ is requested, which implies a high number of cells to protect a low y+ and a properly expansion ratio and y+ is related with the velocity case. If the velocity case is low, for a requested y+ will imply a high rst cell distance, which at the end it is related with the total cell case. This study has used open software called OpenFOAM which is been made to solve Navier-Stokes equations by Computatinal Fluid Dynamics ( CFD from now) between other applications. Results indicate that AFC is able to apply a positive e ect in aerodynamic performance in comparison with baseline case. Some AFC characteristic variables have been studied.
Author :Ronald Douglas Joslin Publisher :AIAA (American Institute of Aeronautics & Astronautics) ISBN 13 : Total Pages :656 pages Book Rating :4.3/5 (91 download)
Book Synopsis Applications of Circulation Control Technologies by : Ronald Douglas Joslin
Download or read book Applications of Circulation Control Technologies written by Ronald Douglas Joslin and published by AIAA (American Institute of Aeronautics & Astronautics). This book was released on 2006 with total page 656 pages. Available in PDF, EPUB and Kindle. Book excerpt: Based on papers from the 2004 NASA/ONR Circulation Control Workshop, this collection is an invaluable, one-of-a-kind resource on the state of the art in circulation control technologies and applications. Filling the information gap between 1986 -- when the last such symposium was held -- and today, it summarizes the applications, experiments, computations and theories related to circulation control, emphasizing fundamental physics, systems analysis and applied research. The papers presented cover a wide variety of aerodynamic and hydrodynamic applications including naval vehicles, fixed-wing aviation, V/STOL platforms, propulsion systems and ground vehicles. Anyone with interests in applied aerodynamics, fluid mechanics and aircraft design will find this book of particular value, as will those seeking a an up-to-date reference work on circulation control and its many current applications.
Book Synopsis Elegance in Flight by : Albert C. Piccirillo
Download or read book Elegance in Flight written by Albert C. Piccirillo and published by . This book was released on 2014 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Internal Flow written by E. M. Greitzer and published by Cambridge University Press. This book was released on 2007-02-26 with total page 739 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the analysis and behaviour of internal flows encountered in propulsion systems, fluid machinery (compressors, turbines and pumps) and ducts (diffusers, nozzles and combustion chambers). The focus is on phenomena that are important in setting the performance of a broad range of fluid devices. The authors show that even for complex processes one can learn a great deal about the behaviour of such devices from a clear understanding and rigorous use of basic principles. Throughout the book they illustrate theoretical principles by reference to technological applications. The strong emphasis on fundamentals, however, means that the ideas presented can be applied beyond internal flow to other types of fluid motion. The book equips students and practising engineers with a range of new analytical tools. These tools offer enhanced interpretation and application of both experimental measurements and the computational procedures that characterize modern fluids engineering.
