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A numerical method to simulate plasma induced electro-hydro-dynamic (EHD) flow is proposed in this study. The numerical model consists of three components, a potential module to simulate temporal potential and electric field generated in the ionized fluid. Secondly, a plasma module to simulate plasma development and charge particle densities. Final...
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... all the simulations, the dielectric material was Kapton with a thickness of 2mm, as used in the experiments. Second order accurate spatial discretization was implemented based on the non-uniform structured staggered grid was considered in the present model, presented in figure 1. In this section, the physical and computational domain considered for numerical simulations along with the description of each of the three components of the plasma-fluid model are presented, along with a flow chart in figure 4. Algorithm and the numerical method implemented in each module are explained and their respective validations, by comparing with previous experimental and numerical studies, are presented. ...
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... boundary condition for potential at the interface of fluid and dielectric material was considered according to, In the staggered grid arrangement used in the present model, figure 1, the potential was calculated at center of each cell of the grid. Second order accurate spatial discretization was used for all the terms in potential Poisson equation (1) and (3). ...
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... AC power source of voltage 10kV pp and frequency 24kHz applied to the anode was simulated. The results are compared with experimental flow development visualizations, figure 16, to validate the plasma-fluid model and the coupling of individual potential, plasma and fluid components. The validation was carried out by analyzing and comparing experimental and numerical results of the wake development in the quiescent flow generated by the DBD. ...
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... streamline were then compared with the experimental streamline generated around the DBD actuator. Figure 10(a) presents streamline around the edge of the exposed electrode, where the cathode starts, like the experimental and numerical streamline plots presented in [4]. It can be observed from the streamline presented in figure 10(a) that the fluid is pulled towards the dielectric surface, accelerated in the direction of the cathode and further pushed downstream due to the body forces acting on the induced charge, in the ionized air around the electrodes. ...
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... 10(a) presents streamline around the edge of the exposed electrode, where the cathode starts, like the experimental and numerical streamline plots presented in [4]. It can be observed from the streamline presented in figure 10(a) that the fluid is pulled towards the dielectric surface, accelerated in the direction of the cathode and further pushed downstream due to the body forces acting on the induced charge, in the ionized air around the electrodes. Structures like K-H instabilities [46], were resolved by the present model and can also be observed from streamline which are formed due to shear stresses induced by the velocity gradient in the fluid being pulled toward the dielectric surface. ...
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... induced body forces generated by the DBD actuator due to the charge formed in the ionized fluid, leads to generation of vortices in the wake. The vortices gradually develop with time and are eventually dissipated in the wake leading to a free stream fluid flow as seen in figure 10 (b), 11 (f) and 12 (f). The quiescent flow generated by the DBD actuator develops as a vortex, that is formed at the end of anode and grows with time due to the force exerted by the charged species oscillations. ...
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... similar behavior for the quiescent flow development was observed form the visualizations, figure 14. Some previous experimental studies [31], used smoke to visualize the flow downstream of the DBD actuator at smaller frequency of 100Hz to observe the vortex formation, development and eventual dissipation creating a fluid stream. ...
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... the present work several image visualization experiments were performed to analyze the physics of induced flow in a plasma actuator, figure 15. The tested plasma actuators were constructed by two electrodes made of copper tape and a dielectric layer made of Kapton and were mounted in a flat plate. ...
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... dielectric layer presented 100 mm length and 50 mm thickness and the experiments were carried out for a dielectric thicknesses 2 mm. The experiments were conducted in a closed acrylic box, see figure 14(b), to avoid external perturbations. ...
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... that, using an image processor software, we measured the desired distances in pixels and converted them to metric units. The measurements of the wake length and height thus obtained, presented in figure 16, are then compared with numerical results obtained from the plasma-fluid model proposed in this study for validation and analysis if the quiescent flow development in a DBD actuator. ...
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... all the simulations, the dielectric material was Kapton with a thickness of 2mm, as used in the experiments. Second order accurate spatial discretization was implemented based on the non-uniform structured staggered grid was considered in the present model, presented in figure 1. In this section, the physical and computational domain considered for numerical simulations along with the description of each of the three components of the plasma-fluid model are presented, along with a flow chart in figure 4. Algorithm and the numerical method implemented in each module are explained and their respective validations, by comparing with previous experimental and numerical studies, are presented. ...
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... boundary condition for potential at the interface of fluid and dielectric material was considered according to, In the staggered grid arrangement used in the present model, figure 1, the potential was calculated at center of each cell of the grid. Second order accurate spatial discretization was used for all the terms in potential Poisson equation (1) and (3). ...
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... AC power source of voltage 10kV pp and frequency 24kHz applied to the anode was simulated. The results are compared with experimental flow development visualizations, figure 16, to validate the plasma-fluid model and the coupling of individual potential, plasma and fluid components. The validation was carried out by analyzing and comparing experimental and numerical results of the wake development in the quiescent flow generated by the DBD. ...
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... streamline were then compared with the experimental streamline generated around the DBD actuator. Figure 10(a) presents streamline around the edge of the exposed electrode, where the cathode starts, like the experimental and numerical streamline plots presented in [4]. It can be observed from the streamline presented in figure 10(a) that the fluid is pulled towards the dielectric surface, accelerated in the direction of the cathode and further pushed downstream due to the body forces acting on the induced charge, in the ionized air around the electrodes. ...
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... 10(a) presents streamline around the edge of the exposed electrode, where the cathode starts, like the experimental and numerical streamline plots presented in [4]. It can be observed from the streamline presented in figure 10(a) that the fluid is pulled towards the dielectric surface, accelerated in the direction of the cathode and further pushed downstream due to the body forces acting on the induced charge, in the ionized air around the electrodes. Structures like K-H instabilities [46], were resolved by the present model and can also be observed from streamline which are formed due to shear stresses induced by the velocity gradient in the fluid being pulled toward the dielectric surface. ...
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... induced body forces generated by the DBD actuator due to the charge formed in the ionized fluid, leads to generation of vortices in the wake. The vortices gradually develop with time and are eventually dissipated in the wake leading to a free stream fluid flow as seen in figure 10 (b), 11 (f) and 12 (f). The quiescent flow generated by the DBD actuator develops as a vortex, that is formed at the end of anode and grows with time due to the force exerted by the charged species oscillations. ...
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... similar behavior for the quiescent flow development was observed form the visualizations, figure 14. Some previous experimental studies [31], used smoke to visualize the flow downstream of the DBD actuator at smaller frequency of 100Hz to observe the vortex formation, development and eventual dissipation creating a fluid stream. ...
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... the present work several image visualization experiments were performed to analyze the physics of induced flow in a plasma actuator, figure 15. The tested plasma actuators were constructed by two electrodes made of copper tape and a dielectric layer made of Kapton and were mounted in a flat plate. ...
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... dielectric layer presented 100 mm length and 50 mm thickness and the experiments were carried out for a dielectric thicknesses 2 mm. The experiments were conducted in a closed acrylic box, see figure 14(b), to avoid external perturbations. ...
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... that, using an image processor software, we measured the desired distances in pixels and converted them to metric units. The measurements of the wake length and height thus obtained, presented in figure 16, are then compared with numerical results obtained from the plasma-fluid model proposed in this study for validation and analysis if the quiescent flow development in a DBD actuator. ...
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... The use of the leaky dielectric model enables the prediction of droplet deformation in good agreement with experimental observations (López-Herrera et al., 2011;Roghair et al., 2015). The application of electric fields to control fluid flow is being used in diverse industrial processes, such as jet printing, electrical propulsion (Xisto et al., 2015), and biotechnology applications (Mushyam et al., 2019). The numerical simulation of this electrohydrodynamic flow stands out as a way to better understand this type of flow and its behaviour under different conditions of operation. ...
The dynamics of the interface of a fluid jet subjected to an external electrostatic field forming a Taylor cone jet is investigated using a numerical approach. A charge-conservative electrohydrodynamic model is used. In this model, the reduced form of Maxwell's equations for an electrostatic field, a transport equation for electric charges and the Navier-Stokes equations for a laminar flow are solved. The connection between the electric field and the hydrodynamic flow is established by the Maxwell stress tensor, which ensures the description of the electric surface forces. A fluid volume model based on surface compression provides an efficient and robust modulation of the overall behaviour of the electric drive of immiscible flows. Test cases from the literature López-Herrera et al. (2011); Roghair et al. (2015) help us to validate the numerical model. The order of accuracy of the spatial and temporal discretization of the electric field equations is computed through a quasi one-dimensional test case. The primary decay of a Taylor cone beam is then simulated with uniform droplet emission. This simulation is validated with experimental results from the literature Taylor (1969). To analyse the dynamics of the flow, it is proposed to use decomposition methods such as Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) using snapshots of the flow field. The dynamic structures formed by the velocity field and the dynamics of the electric charge determine the fundamental dynamics of the droplet emission. An analysis of the sensitivity of the modes to the sampling frequency is performed. The influence of different inlet velocities on the decomposition is analysed in the spatial and frequency domain. A reduced-order model (ROM) is interpolated from the base POD, and we demonstrate that it can be used to successfully construct the velocity and electric charge along the field. We anticipate numerous applications of this new type of ROM, such as for accelerating electrohydrodynamic calculations as surrogate models in digital twins.
... Considering the importance of flow fields manipulation, in the last two decades, plasma actuators have attracted a significant interest from the scientific community around the world (Nunes-Pereira et al., 2022;Mushyam et al., 2019;Pascoa et al., 2014). These devices, are particularly interesting for active flow control purposes mainly because they are fully electronic and do not use moving mechanical parts which are usually responsible for a significant aircraft weight increase. ...
During the last twenty years dielectric barrier discharge (DBD) plasma actuators have been a topic of interest for flow control and aeronautic applications. They present several advantages such as lightweight, low cost, fast response time and can be easily controlled by simple electronic means. Besides the flow control applications, during the recent years several authors have also proven the ability of plasma actuators for performing simultaneously boundary layer flow control and deicing or anti-icing operations. However, the conventional DBD plasma actuator configuration has shown some weaknesses related to its aerodynamic efficiency and durability. Due to that, during the recent years several authors have developed different DBD plasma actuator configurations with the ambition of improving the induced flow velocity field and/or the durability. Furthermore, new plasma actuator (PA) configurations have been also developed in order to obtain a better actuator efficiency for specific applications. Micro-PA, Nano second PA, Plasma Synthetic Jet Actuator (PSJA), Curved PA, Multiple Encapsulated Electrodes PA, sliding discharge PA, stair-shaped PA and segmented encapsulated * Corresponding Author's Email: fmfr@ubi.pt. Frederico Rodrigues and Jose Pascoa 2 electrodes PA are examples of innovative dielectric barrier discharge plasma actuator configurations that were reported in the literature and which present several different advantages when compared with the conventional one. However, till now, there are no works in the literature explaining the differences between all of these new plasma actuator configurations and discussing which ones are more suitable for each type of application. Considering this background, the current work aims to review all the new plasma actuators configurations and compare the advantages and disadvantages of each configuration for different applications.
... Dielectric barrier discharge plasma actuators are very simple electronic devices that have attracted great interest from the scientific community in recent years [90][91][92]. These devices are capable of imparting a momentum to the adjacent flow that can be used to manipulate the surrounding flow field. ...
Ice accretion is a common issue on aircraft flying in cold climate conditions. The ice accumulation on aircraft surfaces disturbs the adjacent airflow field, increases the drag, and significantly reduces the aircraft's aerodynamic performance. It also increases the weight of the aircraft and causes the failure of critical components in some situations, leading to premature aerodynamic stall and loss of control and lift. With this in mind, several authors have begun to study the thermal effects of plasma actuators for icing control and mitigation, considering both aeronautical and wind energy applications. Although this is a recent topic, several studies have already been performed, and it is clear this topic has attracted the attention of several research groups. Considering the importance and potential of using dielectric barrier discharge (DBD) plasma actuators for ice mitigation, we aim to present in this paper the first review on this topic, summarizing all the information reported in the literature about three major subtopics: thermal effects induced by DBD plasma actuators, plasma actuators' ability in deicing and ice formation prevention, and ice detection capability of DBD plasma actuators. An overview of the characteristics of these devices is performed and conclusions are drawn regarding recent developments in the application of plasma actuators for icing mitigation purposes.
... Physics underlying the relationship between thrust output and electric field distribution have been investigated with different plasma flow control simulation models, which can be classified as phenomenological model [24,25], loosecoupled multi-physics model [26], and close-coupled multiphysics model [27]. The electric field distribution is a key factor for each model to evaluate the thrust and is affected by the applied voltage, electrode geometry, and the space charge distribution. ...
Researches in the plasma actuation are increasingly scrutinizing the methodology to enhance the thrust density for the application in the aerodynamic flow control. In this paper, a new method has been proposed and experimentally evaluated. This method is based on the deposition of nanoscaled structures on the electrode surface and the tuning of the applied voltages and frequency. It is found that the thrust enhancement rate resulted from the incorporation of the nanostructures could be approximately 78 \%, relative to the controlled group, under 14kV and 7kHz. However, a threshold effect has been founded across all of the tested samples, where lower applied voltage and frequency could lead to the decrease in the thrust generation. Capacitor charging effects are basically not sensitive to the introduction of the nanostructures in electrical characteristic. Other experimental features and electric filed simulation results also indicate the effectiveness of introducing nanoscaled structures into DBD plasma actuators, thus providing a new way to improve mechanical performance.
... Appropriate boundary conditions are implemented to ensure the self-consistency of the simulation (including secondary electron emission and dielectric charging). Similar physical models have been used extensively in the simulation of AC-SDBDs in atmospheric air [1,7,[36][37][38]) providing sufficient agreement with experimental findings for the purpose of this work. We note that two of the major assumptions made in the current modeling the SDBD are the neglection of photoionization and the assumption of two-dimensional evolution. ...
We show that the spatio-temporal ElectroHydroDynamic (EHD) force production in surface AC-Dielectric Barrier Discharge (AC-DBD) actuators is strongly influenced by both the streamer regime during the positive phase and the micro-discharge regime during the negative phase. Focusing on the spatial EHD force profiles, we demonstrate that the ionic wind spatial distribution can only be explained by the positive contribution of the streamer regime. The location of maximum ionic wind is found to be directly linked with the maximum elongation of the streamers at several millimeters from the exposed electrode. In both positive and negative phases of the AC-DBD operation, residual volumetric and surface charges once again linked to the streamer formation and afterburn, result to a variety of positive EHD force zones which, when time-averaged in one AC period, contribute to the generation of the experimentally observed induced thin wall jet. Through a thorough elaboration of our numerical results, we provide an illustrative explanation of the EHD force spatio-temporal evolution, showcase the importance of streamers and retrieve a correct representation of the ionic wind spatial profiles when compared to experiments.
... LES approach is more appropriate to capture the details of the computed flow and demonstrate the principle of the internal flow Pendar and Roohi, 2015;Pendar and Roohi, 2018;Kolahan et al., 2019;Roohi et al., 2016). The implementation of the electric field is an important issue for have an accurate simulation and capture the details of the flow precisely which performed on the other similar studies (Mushyam et al., 2019;Abdollahzadeh et al., 2016;Abdollahzadeh et al., 2018). ...
The impetus of the current paper is to conduct numerical evaluations about the fundamental behaviors of the flow in an electrostatic rotary bell sprayer (ERBS) during the formation of the droplets and depositing on a target. The effect of operational parameters like bell rotational speed, shaping air and paint flow rate, electrical charge values and droplet distributions are considered precisely. Here, an Eulerian-Lagrangian algorithm that contains a model for airflow field, spray dynamics, electric charge field, droplet trajectory tracking and wall film dynamics has been extended by using the OpenFOAM package. The fluid dynamics is computed by using a large eddy simulation (LES) turbulence model. The mechanism of atomization is facilitated by the action of the centrifugal force that conducted the disintegrated droplets to the cup edge. Following that, the high-velocity droplets affected by the shaping airflow and electric force are transported towards the workpiece. The effect of the bell rotational speed in comparison with other parameters is dominant. The measured size of the droplets is controlled by increasing the bell rotational speed or decreasing the paint flow rate, in this case, promoting a reduction in droplet size. The droplet size near the bell cup was increased noticeably, however, their radius becomes more uniform at a longer lateral distance. Investigation of the various breakup models is one of the main goals of this work to predict the droplet size more precisely. The Reitz-KHRT, Reitz-Diwakar, Pilch-Erdman and the newly modified TAB model are examined in order to predict the breakup process in the ERBS. As the paint droplets are a viscous fluid a modification of the Taylor Analogy Breakup (TAB) approach taking non-linear influences for large viscosity into account is recommended. The use of the breakup models creates a smaller droplet size and this means they are more sensitive to recirculation regions flow pattern. The implemented wall film function was able to predict the transport in the boundary layer over the target. The numerical results describe exact values for the size, distribution, velocity and trajectory of the particles in ERBS, and these results are important for coating industries, in order to optimize their working conditions.
... During the last years, plasma actuators have been considered very promising devices to perform active flow control [3,4]. These devices are very light, inexpensive, present very fast response time and easy implementation [5,6]. They present several applications in the field of fluid flow control. ...
Plasma actuators are electronic devices commonly used for active flow control. These devices have been shown to be effective in a wide variety of fluids engineering applications. In order to increase the efficiency of these devices, the combination of micro exposed electrodes with stair-shaped dielectric layers is proposed. The flow induced by micro and macro stair-shaped plasma actuators is experimentally evaluated and its mechanical efficiency is estimated. Furthermore, durability tests are performed in order to show that stair-shaped dielectric layers also allow to increase the device lifetime. It is shown that by combining micro exposed electrodes with stair-shaped dielectric layers it is possible to achieve mechanical efficiencies 8 times greater than in a conventional macro actuator. In addition, degradation tests demonstrate that stair-shaped dielectric layers degrade slower and lead to an increased lifetime.
... Various modeling efforts exist through the literature that describes the effect of DBD systems which differ from the level of complexity. The analytic study of Soloviev et al. [16], the numerical simulations [17][18][19][20][21], and the experimental studies of Benard et al. [22] and modeling results of Shi et al. [23] are the recent highlights of the conducted researches to provide the required characteristics of the non-thermal DBD plasma actuators to be used in active flow controls. ...
A simple model for simulating the surface plasma-induced jets is proposed. The characteristics of the wall jet are estimated based on thrust imposed by the plasma and then related to the similarity solution for the viscous wall jet problem to obtain a plasma wall jet velocity profile. Then the plasma-induced flow field outside the plasma discharge region is simulated by simply imposing a plasma wall jet velocity profile in a single streamwise location. The validity of the model for simulating the effect produced by the dielectric barrier discharge (DBD) plasma actuators is tested against some experimental and numerical simulation results.
... DBD plasma actuators are a popular topic of research within the active flow control field. Several authors have studied these devices during the last twenty years considering their flow control applications [21][22][23][24]. These devices present several interesting features such as the absence of mechanical components, fast response time, very low mass, easy implementation and robustness [25,26]. ...
Aircraft being capable of Vertical Takeoff and Landing (VTOL) and hover are increasingly emerging in various critical and routine applications. Rescue missions in roads and environmental disasters, observance and monitoring-based carriers, surveillance and payload carriage in environments that require high maneuverability and controllability are just a few examples in which this type of aircraft is essential. Helicopters are the most typical aircraft in this kind, but concerning the thrusting mechanism, several alternatives are yet in hand. The tendency to equip aircraft with cycloidal rotors (shortly say, cy-clorotors) as means of Vertical TakeOff and Landing thrusters has increased in recent years. These devices present several advantages such as considerably lower noise production and more stable hover and vertical displacements in comparison with conventional screw propellers as used in helicopters. In the present work a novel concept of propulsion system combining two cy-cloidal rotors with a pair-wing system is presented. A double wing assembly is designed to place in between the two cycloro-tors on each side of the aircraft. The bottom wing is intended to divide the flow in two separate portions through the downwash region of the front cycloidal rotor. To improve the efficiency of this propulsion system, the implementation of plasma actuators in the pair-wing system will be experimentally studied. The concept behind this novel propulsion system is explained and numerical and experimental results, that support its operation concept, are presented.
... Dielectric Barrier Discharge (DBD) plasma actuators are a popular topic of research within the active flow control field. Several authors have studied these devices during the last twenty years considering their flow control applications [1][2][3]. These devices present several interesting features such as the absence of mechanical components, fast response time, very low mass, easy implementation and robustness [4][5][6]. ...
An experimental investigation was conducted in order to understand the ability of plasma actuators to operate in three different modes: flow control, ice formation detection and ice accumulation prevention. When plasma actuators are operated with voltage levels, above the breakdown voltage, a plasma discharge surface is generated and with that, an ionic wind is produced. By using this phenomena, plasma actuators may be used to manipulate flow fields and control adjacent flows to the surface in which they are applied. However, a big part of the power applied to the device is dissipated as heat. Due to heat dissipation, the actuator surface temperature rises and the adjacent air is heated. Considering this, actuators may operate as ice prevention devices by heating the surface where they are applied and preventing the ice formation and accumulation. On the other hand, plasma actuators present a behavior similar to a capaci-tor and they may operate as a capacitive sensor. In the presence of water or ice on the top of the surface, the electric field changes and with that, several plasma actuator electrical features change as well. By monitoring that changes, the presence of water or ice on the top of the surface can be detected and the plasma actua-tor may be used as an ice sensor device. Therefore, in the present study a plasma actuator was experimentally tested operating in these three different operation modes and its feasibility to perform these different tasks is shown.
