Study Of The Boundary Layer Flow Control Using Synthetic Jets By Means Of Spectro Consistent Discretizations
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Study Of The Boundary Layer Flow Control Using Synthetic Jets By Means Of Spectro Consistent Discretizations
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Author : David Duran Perez
language : en
Publisher:
Release Date : 2017
Study Of The Boundary Layer Flow Control Using Synthetic Jets By Means Of Spectro Consistent Discretizations written by David Duran Perez and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
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.
Scientific And Technical Aerospace Reports
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Author :
language : en
Publisher:
Release Date : 1986
Scientific And Technical Aerospace Reports written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1986 with Aeronautics categories.
International Aerospace Abstracts
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Author :
language : en
Publisher:
Release Date : 1998
International Aerospace Abstracts written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with Aeronautics categories.
Commonwealth Of Independent States Aerospace Science And Technology 1992 A Bibliography With Indexes
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Author :
language : en
Publisher:
Release Date : 1993
Commonwealth Of Independent States Aerospace Science And Technology 1992 A Bibliography With Indexes written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with categories.
Government Reports Annual Index
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Author :
language : en
Publisher:
Release Date : 1985
Government Reports Annual Index written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1985 with Research categories.
Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.
Comprehensive Dissertation Index
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Author :
language : en
Publisher:
Release Date : 1989
Comprehensive Dissertation Index written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1989 with Dissertations, Academic categories.
Numerical Study Of Active Flow Control Using Synthetic Jets
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Author : Jeremy Dennis Roth
language : en
Publisher:
Release Date : 2003
Numerical Study Of Active Flow Control Using Synthetic Jets written by Jeremy Dennis Roth and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with categories.
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.
Investigation Of Synthetic Jet Flow Control Parameters For The Mitigation Of Laminar Boundary Layer Separation
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Author : Mark Alexander Feero
language : en
Publisher:
Release Date : 2018
Investigation Of Synthetic Jet Flow Control Parameters For The Mitigation Of Laminar Boundary Layer Separation written by Mark Alexander Feero and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.
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.
The Isolated Synthetic Jet In Crossflow
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Author : Norman W. Schaeffler
language : en
Publisher: BiblioGov
Release Date : 2013-08
The Isolated Synthetic Jet In Crossflow written by Norman W. Schaeffler and has been published by BiblioGov this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-08 with categories.
An overview of the data acquisition, reduction, and uncertainty of experimental measurements made of the flowfield created by the interaction of an isolated synthetic jet and a turbulent boundary layer is presented. The experimental measurements were undertaken to serve as the second of three computational fluid dynamics validation databases for Active Flow Control. The validation databases were presented at the NASA Langley Research Center Workshop on CFD Validation of Synthetic Jets and Turbulent Separation Control in March, 2004. Detailed measurements were made to document the boundary conditions for the flow and also for the phase-averaged flowfield itself. Three component Laser-Doppler Velocimetry, 2-D Particle Image Velocimetry, and Stereo Particle Image Velocimetry were utilized to document the phase-averaged velocity field and the turbulent stresses.
Boundary Layer Control Of A Circular Cylinder Using A Synthetic Jet
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Author : Christopher K. Smith
language : en
Publisher:
Release Date : 2005
Boundary Layer Control Of A Circular Cylinder Using A Synthetic Jet written by Christopher K. Smith and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2005 with Base flow (Aerodynamics) categories.