This research explores the fundamental mechanisms underlying electrical discharges in dielectric barrier discharge (DBD) reactors. Specifically, we investigate how voltage parameters, such as amplitude, frequency, and waveform, affect plasma characteristics .Numerical simulations reveal that alterations in these parameters can significantly impact the spatial distribution of energy within the plasma. These findings demonstrate that precise control over plasma properties can be achieved through fine-tuning voltage parameters, thereby optimizing DBD reactor performance for applications such as treating water contaminated with volatile organic compounds, generating high-purity ozone for medical purposes, and depositing thin polymer films. This research represents a significant step forward in the design and operation of DBD reactors across various industries.

A numerical simulation method is employed to investigate the effect of the steady multiple plasma body forces on the flow field of stalled NACA 0015 airfoil. The plasma body forces created by multiple Dielectric Barrier Discharge (DBD) actuators are modeled with a phenomenological plasma method coupled with 2-dimensional compressible turbulent flow equations. The body force distribution is assumed to vary linearly in the triangular region around theactuator. The equations are solved using adual-timeimplicit finite volume method on unstructured grids. In this paper, the responses of the separated flow field to the effects of single and multiple DBD actuators over the broad range of angles of attack (90− 300) are studied. The effects of the actuators positions on the flow field are also investigated. It is shown that the DBD have a significant effect on flow separation control in low Reynolds number aerodynamics.

Flow control to reduce drag and increase drag and finally increase the ratio of drag to drag (L/D) has always been the focus of aerodynamic scientists. There are many methods to reduce induced drag. The use of DBD plasma operators is one of the newest methods in reducing induced drag. In this research, in order to investigate the performance of DBD plasma actuators, six configurations of plasma actuators have been used as virtual winglets. Experiments have been performed on the wing with the NACA0012 airfoil. These experiments have been carried out in two Reynolds numbers 150,000 and 300,000 and in two voltages, 6 kV and 10 kV and different angles of attack. The results of this research show that the use of this type of plasma actuator at the tip of the wing as a virtual winglet can increase the lift to drag ratio by about 25% in some cases and the use of two small circular and large linear configurations. respectively, they have the best performance compared to other models for use as a virtual winglet.

In this study, direct conversion of methane to methanol in the plasma process was attended. Besides, RSM modeling was used to optimize and evaluate parameters such as voltage, the flow rate of CH4, Ar, and external electrode length. RSM prediction model by the desired condition including minimized Ar (20 mL/min), O2 (2 mL/min), CH4 (2 mL/min), and voltage (4 kV) was used to determine the effect of Ar and CH4 in reactions. The results showed that increasing the Ar flow from 20 to 100 mL/min led to less methanol mole percent. On the other hand, enhancement in methane flow rate from 2 to 12 mL/min was the reason for raising the methanol mole percent at the reactor outlet. To determine how modifying the length of the external electrode affected the mole percent of methanol, the length was lowered from 12.5 to 2 cm, clearly reducing the amount of methane converted. However, it was effective in raising the methanol mole percent to 3% in E.EFF 0.13 mmole/kJ and length of electrode 4 cm. As well as the methanol mole percent in the least energy efficiency E.EFF 0.045 mmole/kJ detected at 2.27%. To summarize, in DBD plasma reactor by direct conversion of methane, increasing in voltage and Ar flow rate had a significant influence on the progress of the process which had an unfavorable effect on methanol mole percent. Meanwhile, the enhancement of CH4   flow rate had an impressive effect on the raising of methanol. Furthermore, the influence of oxygen flow was negligible.

Active control of airflow by using Dielectric-Barrier-Discharge (DBD) is a recent development in flow control theory. Low-weight, low power consumption, no moving parts and flexibility of use are some of its advantages over passive control methods. In this paper, a User Defined Function (UDF) code was hooked into the main flow solver code to model the momentum injected to the flow by DBD actuator. Among different methods that were proposed, Shyy numerical method is selected. The selection process is based on pros and cons of different first principle and phenomenological methods which were published in recent years. In order to validate the results of the air flow in the presence of DBD actuator two test cases are selected, the flow around the Flat Plate and NACA 0015 airfoil. Different flow variables including the velocity profile and pressure distributions are obtained and compared to the reference data. 3D effects of DBD actuators are also investigated by using a NACA 0015 wing model. Two tests are carried out. First, the effect of doubling the DBD field is studied. After doubling the strength of DBD field, the control power of actuator enhanced. Pressure distribution in the midpoint of wing clarifies this fact. Second, the effect of span-wise DBD actuators is investigated. In three locations DBD roll installed on the wing platform and its effect on the flow variables carried out. This experiment clarified that the best location to use DBD plasma actuators would be the onset of flow separation. In this location, the lift to drag ratio of the wing is maximum. Also we studied the DBD parameters which affect the Ionic wind strength, Frequency and Voltage of the power supply. Increasing voltage and frequency would make plasma more effective (this is also concluded from lift to drag ratio) but the trend is not linear for voltage.

Ahmed body is a standard configuration of road vehicles and most of the studies of automobile aerodynamics are performed based on it. In this paper, the plasma actuator was used as an active flow control method to control the flow around the rear part of the Ahmed body with the rear slant angle of 25° . Experiments were carried out in a wind tunnel at two different velocities of U=10m/s and U=20m/s using steady and unsteady excitations. The hot-wire anemometer was used to measure the vortex shedding frequency at the downstream of the body. Pressure distribution was measured using 52 sensors and total drag force was extracted with a load cell. Furthermore, smoke flow visualization was employed to investigate the flow pattern around the body. The results showed that the plasma actuator was more effective on the pressure distribution and total drag force at the velocity of U=10m/s. In fact, by applying steady and unsteady excitations there was 7. 3% and 5% drag reduction; respectively. While at the velocity of U=20m/s; the actuator had no significant effect on pressure distribution and total drag. As a remarkable result, the plasma actuator, especially in the steady actuation, has demonstrated its effectiveness on dispersing the longitudinal vortices and suppressing the separated flow on the rear slant at low velocities.

In this paper, boundary layer control technique is investigated on the NREL-5MW offshore baseline wind turbine blade with numerical simulation of linear DBD plasma actuator in a three-dimensional manner. This wind turbine uses pitch control system to adjust its generated power above its rated speed; but below that the controller is inactive. In the current study, operating condition is set such that the control system is off. Plasma actuator consists of two electrode and dielectric materials. One of these electrodes is connected with the air and another one is encapsulated with the dielectric material. When the necessary high-level AC voltage is applied to electrodes, electric field forms around the actuator and an induced wall jet forms with the ionization of the air around the actuator. Electrostatic model is applied to simulate the effects of plasma actuator and the resulted body force is inserted into flow momentum equations. In the present study, three different control cases are studied. Results show that in all cases, using this actuator leads to improvement of the velocity profile in controlled section, which influences on pressure distribution and results in rotor torque increment. Finally, increasing in torque leads to growth in produced power of the wind turbine. The highest increment in output power occurs when the actuator is installed near the root of the blade in the spanwise direction and before low-speed region in the chordwise direction.

In this study, direct conversion of methane to methanol in the plasma process was attended. Besides, RSM modeling was used to optimize and evaluate parameters such as voltage, the flow rate of CH4, Ar, and external electrode length. RSM prediction model by the desired condition including minimized Ar (20 mL/min), O2 (2 mL/min), CH4 (2 mL/min), and voltage (4 kV) was used to determine the effect of Ar and CH4 in reactions. The results showed that increasing the Ar flow from 20 to 100 mL/min led to less methanol mole percent. On the other hand, enhancement in methane flow rate from 2 to 12 mL/min was the reason for raising the methanol mole percent at the reactor outlet. To determine how modifying the length of the external electrode affected the mole percent of methanol, the length was lowered from 12.5 to 2 cm, clearly reducing the amount of methane converted. However, it was effective in raising the methanol mole percent to 3% in E.EFF 0.13 mmole/kJ and length of electrode 4 cm. As well as the methanol mole percent in the least energy efficiency E.EFF 0.045 mmole/kJ detected at 2.27%. To summarize, in DBD plasma reactor by direct conversion of methane, increasing in voltage and Ar flow rate had a significant influence on the progress of the process which had an unfavorable effect on methanol mole percent. Meanwhile, the enhancement of CH4   flow rate had an impressive effect on the raising of methanol. Furthermore, the influence of oxygen flow was negligible.

In this paper, a one-dimensional simulation for discus plate dielectric barrier discharge (DBD) is done by COMSOL Multiphysics software. The effects of different parameters such as voltage, frequency, dielectric thickness, dielectric constant and electrode’ s material on the temperature and density of electrons are investigated, it is found that secondary electron emission coefficient of the electrode, dielectric constant and the thickness of dielectric have a direct impact on the density of electron. The voltage increment from 5 to 50 kV, causes electron density growing from 4×1017m-3 to 3. 2×1018m-3. Based on this study, electron density could reach up to the orders of 1018m-3 by optimizing material and dimensions of dielectric and electrodes without applying high voltage and frequency which results a significant lower production cost.

The boundary-layer control authority of a DBD plasma actuator using surface mounted hot-film sensors is evaluated. Wind tunnel experiments on a wind-turbine blade section were established at a Reynolds number of 0. 27 × 106. Aerodynamic performance of the wind-turbine blade section for both plasma-ON and plasma-OFF modes are evaluated using measurements made by both surface pressure and wake survey behind the model. Two distinct boundary-layer states are recognized. A state which occurs at the onset and in proximity of the deep stall, which is affected by the low-frequency instabilities of the separated flow. In this case, the steady actuation of plasma imparts local momentum on the nearby flow, eliminating the instabilities, hence, reattaching the detached flow. The other state happens beyond the static stall angle of attack of the airfoil where the flow over the suction side of the airfoil is fully separated and coexistence of both the leading edge and the trailing edge shear-layer instabilities and natural trailing edge vortex shedding is the underlying mechanism. In this case, although the plasma actuator eliminates the instabilities, to some extent, but the corresponding momentum injection is not efficient to stabilize and reattach the flow.