The Experts below are selected from a list of 105 Experts worldwide ranked by ideXlab platform
Thomas Corke - One of the best experts on this subject based on the ideXlab platform.
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Single-dielectric barrier discharge plasma actuator modelling and validation
Journal of Fluid Mechanics, 2011Co-Authors: Benjamin Mertz, Thomas CorkeAbstract:Single-dielectric barrier discharge (SDBD) plasma actuators have gained a great deal of world-wide interest for flow-control applications. With this has come the need for flow-interaction models of plasma actuators that can be used in computational flow simulations. SDBD plasma actuators consist of two electrodes: one uncovered and exposed to the air and the other encapsulated by a dielectric material. An AC electric potential is supplied to the electrodes. When the AC potential is large enough, the air in the region over the encapsulated electrode ionizes. The ionized air in the presence of the electric field results in a space–time dependent Body Force Vector field. The Body Force is the mechanism for flow control. This study describes a semi-empirical model that has been developed to capture the dynamic nature of the local air ionization and time-dependent Body Force Vector distribution. Validation of the model includes comparisons to experimentally measured space–time charge distribution and the time-resolved and time-averaged Body Force. Two flow simulations are then used to further validate the SDBD plasma actuator model. These involved an impulsively started plasma actuator in still air, and the flow around a circular cylinder in which plasma actuators were used to suppress the Karman vortex street. In both cases, the simulations agreed well with the experiments.
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dielectric barrier discharge plasma actuators for flow control
Annual Review of Fluid Mechanics, 2010Co-Authors: Thomas Corke, Lon C Enloe, Stephen P WilkinsonAbstract:The term plasma actuator has now been a part of the fluid dynamics flow-control vernacular for more than a decade. A particular type of plasma actuator that has gained wide use is based on a single–dielectric barrier discharge (SDBD) mechanism that has desirable features for use in air at atmospheric pressures. For these actuators, the mechanism of flow control is through a generated Body-Force Vector field that couples with the momentum in the external flow. The Body Force can be derived from first principles, and the effect of plasma actuators can be easily incorporated into flow solvers so that their placement and operation can be optimized. They have been used in a wide range of internal and external flow applications. Although initially considered useful only at low speeds, plasma actuators are effective in a number of applications at high subsonic, transonic, and supersonic Mach numbers, owing largely to more optimized actuator designs that were developed through better understanding and modeling of...
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Single-Dielectric Barrier Discharge Plasma Enhanced Aerodynamics: Concepts, Optimization, and Applications
Journal of Propulsion and Power, 2008Co-Authors: Thomas Corke, Martiqua L. Post, Dmitry M OrlovAbstract:This paper deals with the physics and design of single dielectric barrier discharge plasma actuators for enhanced aerodynamics in a variety of applications. The actuators consist of two electrodes: one exposed to the air and the other covered by a dielectric material. The electrodes are supplied with an alternating current voltage that, at high enough levels, causes the air over the covered electrode to ionize. The ionized air, in the presence of the electric field produced by the electrode geometry, results in a Body Force Vector that acts on the ambient air. The Body Force is the mechanism for active aerodynamic control. The plasma generation is a dynamic process within the alternating current cycle. The Body Force per unit volume of plasma has been derived from first principles and implemented in numerical flow simulations. Models for the time and space dependence of the Body Force on the input voltage amplitude, frequency, electrode geometry, and dielectric properties have been developed and used along with experiments to optimize actuator performance. This paper presents results that highlight the plasma actuator characteristics and modeling approach. This is followed by overviews of some of the applications that include leading-edge separation control on airfoils, dynamic-stall vortex control on oscillating airfoils, and trailing-edge separation control on simulated turbine blades.
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sdbd plasma enhanced aerodynamics concepts optimization and applications
Progress in Aerospace Sciences, 2007Co-Authors: Thomas Corke, Martiqua Post, Dmitry M OrlovAbstract:Abstract This paper provides an overview of the physics and design of single dielectric barrier discharge (SDBD) plasma actuators for enhanced aerodynamics in a variety of applications. The actuators consist of two electrodes, one exposed to the air and the other covered by a dielectric material. The electrodes are supplied with an ac voltage that at high enough levels, causes the air over the covered electrode to ionize. The ionization of the air is a dynamic process within the ac cycle. The ionized air, in the presence of the electric field produced by the electrode geometry, results in a Body Force Vector that acts on the ambient air. The Body Force is the mechanism for active aerodynamic control. The Body Force per unit volume of plasma has been derived from first principles and implemented in numerical flow simulations. This utilizes models for the time and space dependence of the air ionization on the input voltage amplitude, frequency, electrode geometry and dielectric properties that have been developed and bench-marked with experiments. The experiments and model suggest approaches that can maximize the performance of the plasma actuators. A sample implementation of an actuator model in a numerical flow simulation consisting of leading-edge separation control on an airfoil along with an experimental benchmark is then presented.
Zhongqi Quentin Yue - One of the best experts on this subject based on the ideXlab platform.
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Yue’s solution of classical elasticity in n-layered solids: Part 1, mathematical formulation
Frontiers of Structural and Civil Engineering, 2015Co-Authors: Zhongqi Quentin YueAbstract:This paper presents the exact and complete fundamental singular solutions for the boundary value problem of a n-layered elastic solid of either transverse isotropy or isotropy subject to Body Force Vector at the interior of the solid. The layer number n is an arbitrary nonnegative integer. The mathematical theory of linear elasticity is one of the most classical field theories in mechanics and physics. It was developed and established by many well-known scientists and mathematicians over 200 years from 1638 to 1838. For more than 150 years from 1838 to present, one of the remaining key tasks in classical elasticity has been the mathematical derivation and formulation of exact solutions for various boundary value problems of interesting in science and engineering. However, exact solutions and/or fundamental singular solutions in closed form are still very limited in literature. The boundary-value problems of classical elasticity in n-layered and graded solids are also one of the classical problems challenging many researchers. Since 1984, the author has analytically and rigorously examined the solutions of such classical problems using the classical mathematical tools such as Fourier integral transforms. In particular, he has derived the exact and complete fundamental singular solutions for elasticity of either isotropic or transversely isotropic layered solids subject to concentrated loadings. The solutions in nlayered or graded solids can be calculated with any controlled accuracy in association with classical numerical integration techniques. Findings of this solution formulation are further used in the companion paper for mathematical verification of the solutions and further applications for exact and complete solutions of other problems in elasticity, elastodynamics, poroelasticty and thermoelasticity. The mathematical formulations and solutions have been named by other researchers as Yue’s approach, Yue’s treatment, Yue’s method and Yue’s solution.postprin
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yue s solution of classical elasticity in n layered solids part 2 mathematical verification
Frontiers of Structural and Civil Engineering, 2015Co-Authors: Zhongqi Quentin YueAbstract:This paper presents the exact and complete fundamental singular solutions for the boundary value problem of a n-layered elastic solid of either transverse isotropy or isotropy subject to Body Force Vector at the interior of the solid. The layer number n is an arbitrary nonnegative integer. The mathematical theory of linear elasticity is one of the most classical field theories in mechanics and physics. It was developed and established by many well-known scientists and mathematicians over 200 years from 1638 to 1838. For more than 150 years from 1838 to present, one of the remaining key tasks in classical elasticity has been the mathematical derivation and formulation of exact solutions for various boundary value problems of interesting in science and engineering. However, exact solutions and/or fundamental singular solutions in closed form are still very limited in literature. The boundary-value problems of classical elasticity in n-layered and graded solids are also one of the classical problems challenging many researchers. Since 1984, the author has analytically and rigorously examined the solutions of such classical problems using the classical mathematical tools such as Fourier integral transforms. In particular, he has derived the exact and complete fundamental singular solutions for elasticity of either isotropic or transversely isotropic layered solids subject to concentrated loadings. The solutions in n-layered or graded solids can be calculated with any controlled accuracy in association with classical numerical integration techniques. Findings of this solution formulation are further used in the companion paper for mathematical verification of the solutions and further applications for exact and complete solutions of other problems in elasticity, elastodynamics, poroelasticty and thermoelasticity. The mathematical formulations and solutions have been named by other researchers as Yue’s approach, Yue’s treatment, Yue’s method and Yue’s solution.
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Yue’s solution of classical elasticity in n-layered solids: Part 2, mathematical verification
Frontiers of Structural and Civil Engineering, 2015Co-Authors: Zhongqi Quentin YueAbstract:This paper presents the exact and complete fundamental singular solutions for the boundary value problem of a n-layered elastic solid of either transverse isotropy or isotropy subject to Body Force Vector at the interior of the solid. The layer number n is an arbitrary nonnegative integer. The mathematical theory of linear elasticity is one of the most classical field theories in mechanics and physics. It was developed and established by many well-known scientists and mathematicians over 200 years from 1638 to 1838. For more than 150 years from 1838 to present, one of the remaining key tasks in classical elasticity has been the mathematical derivation and formulation of exact solutions for various boundary value problems of interesting in science and engineering. However, exact solutions and/or fundamental singular solutions in closed form are still very limited in literature. The boundary-value problems of classical elasticity in n-layered and graded solids are also one of the classical problems challenging many researchers. Since 1984, the author has analytically and rigorously examined the solutions of such classical problems using the classical mathematical tools such as Fourier integral transforms. In particular, he has derived the exact and complete fundamental singular solutions for elasticity of either isotropic or transversely isotropic layered solids subject to concentrated loadings. The solutions in n-layered or graded solids can be calculated with any controlled accuracy in association with classical numerical integration techniques. Findings of this solution formulation are further used in the companion paper for mathematical verification of the solutions and further applications for exact and complete solutions of other problems in elasticity, elastodynamics, poroelasticty and thermoelasticity. The mathematical formulations and solutions have been named by other researchers as Yue’s approach, Yue’s treatment, Yue’s method and Yue’s solution.
Dmitry M Orlov - One of the best experts on this subject based on the ideXlab platform.
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Single dielectric barrier discharge plasma enhanced aerodynamics: physics, modeling and applications
Experiments in Fluids, 2009Co-Authors: Thomas C. Corke, Martiqua L. Post, Dmitry M OrlovAbstract:The term “plasma actuator” has been a part of the fluid dynamics flow control vernacular for more than a decade. A particular type of plasma actuator that has gained wide use is based on a single dielectric barrier discharge (SDBD) mechanism that has desirable features for use in air at atmospheric pressures. For these actuators, the mechanism of flow control is through a generated Body Force Vector that couples with the momentum in the external flow. The Body Force can be derived from first principles and the plasma actuator effect can be easily incorporated into flow solvers so that their placement and operation can be optimized. They have been used in a wide range of applications that include bluff Body wake control; lift augmentation and separation control on a variety of lifting surfaces ranging from fixed wings with various degrees of sweep, wind turbine rotors and pitching airfoils simulating helicopter rotors; flow separation and tip-casing clearance flow control to reduce losses in turbines, to control flow surge and stall in compressors; and in exciting instabilities in boundary layers at subsonic to supersonic Mach numbers for turbulent transition control. New applications continue to appear through programs in a growing number of US universities and government laboratories, as well as in Germany, France, England, Netherland, Russia, Japan and China. This paper provides an overview of the physics, design and modeling of SDBD plasma actuators. It then presents their use in a number of applications that includes both numerical flow simulations and experiments together.
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Single-Dielectric Barrier Discharge Plasma Enhanced Aerodynamics: Concepts, Optimization, and Applications
Journal of Propulsion and Power, 2008Co-Authors: Thomas Corke, Martiqua L. Post, Dmitry M OrlovAbstract:This paper deals with the physics and design of single dielectric barrier discharge plasma actuators for enhanced aerodynamics in a variety of applications. The actuators consist of two electrodes: one exposed to the air and the other covered by a dielectric material. The electrodes are supplied with an alternating current voltage that, at high enough levels, causes the air over the covered electrode to ionize. The ionized air, in the presence of the electric field produced by the electrode geometry, results in a Body Force Vector that acts on the ambient air. The Body Force is the mechanism for active aerodynamic control. The plasma generation is a dynamic process within the alternating current cycle. The Body Force per unit volume of plasma has been derived from first principles and implemented in numerical flow simulations. Models for the time and space dependence of the Body Force on the input voltage amplitude, frequency, electrode geometry, and dielectric properties have been developed and used along with experiments to optimize actuator performance. This paper presents results that highlight the plasma actuator characteristics and modeling approach. This is followed by overviews of some of the applications that include leading-edge separation control on airfoils, dynamic-stall vortex control on oscillating airfoils, and trailing-edge separation control on simulated turbine blades.
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sdbd plasma enhanced aerodynamics concepts optimization and applications
Progress in Aerospace Sciences, 2007Co-Authors: Thomas Corke, Martiqua Post, Dmitry M OrlovAbstract:Abstract This paper provides an overview of the physics and design of single dielectric barrier discharge (SDBD) plasma actuators for enhanced aerodynamics in a variety of applications. The actuators consist of two electrodes, one exposed to the air and the other covered by a dielectric material. The electrodes are supplied with an ac voltage that at high enough levels, causes the air over the covered electrode to ionize. The ionization of the air is a dynamic process within the ac cycle. The ionized air, in the presence of the electric field produced by the electrode geometry, results in a Body Force Vector that acts on the ambient air. The Body Force is the mechanism for active aerodynamic control. The Body Force per unit volume of plasma has been derived from first principles and implemented in numerical flow simulations. This utilizes models for the time and space dependence of the air ionization on the input voltage amplitude, frequency, electrode geometry and dielectric properties that have been developed and bench-marked with experiments. The experiments and model suggest approaches that can maximize the performance of the plasma actuators. A sample implementation of an actuator model in a numerical flow simulation consisting of leading-edge separation control on an airfoil along with an experimental benchmark is then presented.
Mohammadreza Movahhedi - One of the best experts on this subject based on the ideXlab platform.
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Power improvement of NREL 5-MW wind turbine using multi-DBD plasma actuators
Energy Conversion and Management, 2017Co-Authors: Abbas Ebrahimi, Mohammadreza MovahhediAbstract:Abstract The present study numerically investigates the feasibility of using multiple dielectric barrier discharge (multi-DBD) plasma actuators as a novel approach for active flow control over a large horizontal axis wind turbine rotor. The National Renewable Energy Laboratory 5 MW offshore wind turbine is used as the baseline case. This turbine uses pitch control system to adjust the generated power above its rated wind speeds, but at lower speeds, this system remains inactive. In this paper, the operational condition speed is considered lower than the rated wind speed. The mathematical electro-static model is implemented to simulate the effects of plasma actuator on the external flow and the results are incorporated into Navier-Stokes equations as a Body Force Vector. A configuration of multi-DBD plasma actuators was located at inboard part of the blade along the span that produced a chord-wise Body Force. Three different cases have been considered based on the number of active actuators. It is revealed that the use of multi-DBD actuators placed parallelly one behind the other could enhance the induced velocity; this affects the pressure distribution and increases the aerodynamic torque. Results showed that, for the cases studied, the turbine power increments are respectively 0.85%, 0.77%, and 0.66%.
Martin Pitoňák - One of the best experts on this subject based on the ideXlab platform.
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evidence of mantle upwelling downwelling and localized subduction on venus from the Body Force Vector analysis
Planetary and Space Science, 2018Co-Authors: Luigi Sante Zampa, Robert Tenzer, Mehdi Eshagh, Martin PitoňákAbstract:Abstract Considering that Venus has a size very similar to Earth, thermal evolution of both planets should be comparable. Nonetheless, there is no clear evidence of plate tectonics or plate motions on Venus. Instead, various surface deformations attributed to volcanism, resurfacing, localized subduction and other geologic processes were recognized on the planet. In this study we attempt to classify the origin of lithospheric Forces on Venus based on using topographic and gravity information. For this purpose, we also estimate the Venusian crustal thickness. In agreement with findings from previous studies, the signature of past or recent global tectonism in the Body-Force Vector pattern on Venus is absent, while exhibiting only regional anomalies. The maximum intensity inferred in the Atla and Beta Regios is likely attributed to mantle upwelling. This is also confirmed by the gravity-topography spectral correlation and admittance analysis that shows the isostatic relaxation of these volcanic regions. The regional Body-Force pattern in the Bell Regio suggests that a much less pronounced Force intensity there is possibly related to crustal load of lava flows. Elsewhere, the Body-Force intensity is relatively weak, with slightly more pronounced intensity around the Ishtar Terra and the Arthemis Chasmata. The Body-Force pattern in the Arthemis Chasmata supports the hypothesis that coronae structures are the result of mantle upwelling and the subsequent (localized) plume-induced subduction with only limited horizontal crustal motions. The prevailing divergent pattern of Body-Force Vectors in the Ishtar Terra region suggests the presence of tensional Forces due to the downwelling mantle flow that is responsible for a crustal thickening along the Freyja and Maxwell Montes. Except for the Atla and Beta Regios where the isostasy is relaxed by the (active) mantle plumes, the crustal thickness is spatially highly correlated with the topography, with a thin crust under the plains and a thick crust under the plateaus. The maximum Moho depth under the Maxwell Montes in the Ishtar Terra exceeds 90 km.
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Evidence of mantle upwelling/downwelling and localized subduction on Venus from the Body-Force Vector analysis
Planetary and Space Science, 2018Co-Authors: Luigi Sante Zampa, Robert Tenzer, Mehdi Eshagh, Martin PitoňákAbstract:Abstract Considering that Venus has a size very similar to Earth, thermal evolution of both planets should be comparable. Nonetheless, there is no clear evidence of plate tectonics or plate motions on Venus. Instead, various surface deformations attributed to volcanism, resurfacing, localized subduction and other geologic processes were recognized on the planet. In this study we attempt to classify the origin of lithospheric Forces on Venus based on using topographic and gravity information. For this purpose, we also estimate the Venusian crustal thickness. In agreement with findings from previous studies, the signature of past or recent global tectonism in the Body-Force Vector pattern on Venus is absent, while exhibiting only regional anomalies. The maximum intensity inferred in the Atla and Beta Regios is likely attributed to mantle upwelling. This is also confirmed by the gravity-topography spectral correlation and admittance analysis that shows the isostatic relaxation of these volcanic regions. The regional Body-Force pattern in the Bell Regio suggests that a much less pronounced Force intensity there is possibly related to crustal load of lava flows. Elsewhere, the Body-Force intensity is relatively weak, with slightly more pronounced intensity around the Ishtar Terra and the Arthemis Chasmata. The Body-Force pattern in the Arthemis Chasmata supports the hypothesis that coronae structures are the result of mantle upwelling and the subsequent (localized) plume-induced subduction with only limited horizontal crustal motions. The prevailing divergent pattern of Body-Force Vectors in the Ishtar Terra region suggests the presence of tensional Forces due to the downwelling mantle flow that is responsible for a crustal thickening along the Freyja and Maxwell Montes. Except for the Atla and Beta Regios where the isostasy is relaxed by the (active) mantle plumes, the crustal thickness is spatially highly correlated with the topography, with a thin crust under the plains and a thick crust under the plateaus. The maximum Moho depth under the Maxwell Montes in the Ishtar Terra exceeds 90 km.