In this study, a novel fluidic Jet actuator is designed to control flow separation on a NACA0015 airfoil at various angles of attack. The U-shaped Jet actuator has two rectangular slots implemented near the leading edge of the airfoil. It is driven by a piston mechanism and operates at three excitation frequencies. Depending on the motion of the mechanism, a synchronized Jet flow is generated by blowing and suction at the dual exits of the actuator slots. The experimental studies are carried out in a subsonic wind tunnel. The unsteady 2D Computational Fluid Dynamics simulations are performed by Detached Eddy Simulation with the SST k-ω turbulence model where measured Jet velocities at the exits of the actuator slots are imposed as boundary conditions to mimic motion of the piston. The results at the on-mode and off-mode of the actuator are evaluated in terms of surface pressure coefficient distributions on the airfoil and averaged aerodynamic force coefficients. At low angles of attack, there is an adequate match between numerical and experimental results for the base flow without any control. At higher angles of attack, flow separation becomes considerably dominant and stall prevention by active flow control is detected especially at high excitation frequencies‎.

Recently، active ow control by dielectric barrier discharge (DBD) plasma actuators has been increased. These actuators are known as more ecient، low-cost، without the need of moving parts، low power consumption، small size، low weight، easy installation and without delay in control. All these features have attracted researcherstousethisactuatorinavarietyofcases، such as turbulence ow control، laminar to turbulent transition suppression، separation control، drag reduction and mitigationofnoisepollution. However، mostofthestudiessu erfromlackofanaccuratenumericalmodelwhich cansimulatethisphenomenonindetails. Computational analysisofthisphenomenonisverycomplexanddicult due to a combination of ionization phenomena and the interaction of the uid ow with the actuator e ects. For the exact solution of this phenomenon in certain conditions، Maxwell and Navier-Stokes equations must be combined، while this non-linear solution combination willbeverydicult. Oneofthemodelsformodelingthe interactionbetweentheactuatorand uid owisanelectrostatic model which adds the actuator e ect as source termsinthemomentumequationsbysolvingtheelectrical potential equation and charge density equation. In this study، an improvement is proposed to enhance the simulation accuracy of a model used for plasma actuator e ect under interaction with uid ow. In the modied model suggested، a boundary condition for charge distribution on the charged surface is presented based on a relationship between the independent electrical potential and charge density equations. Further، semi-empirical relations are utilized to calculate the produced plasma extend. The e ect of the actuator on induced Jet shows a good agreement with experimental results and does not need experimental tests for parametric calibration.

The aim of present study is to delay stall and increase the aerodynamic performance of NASA GAW-(2) supercritical airfoil by using a synthetic Jet actuator. In this research, the diaphragm movement and the generated Jet flow of the actuator are numerically simulated using Fluent software. The flow simulation was performed by solving the Navier-Stokes equations under turbulent and unsteady flow conditions in the subsonic flow. Before simulating the actuator, the flow around the based airfoil is first numerically simulated and aerodynamic properties of the airfoil are compared and validated with existing experimental results. In the next step, the effect of the synthetic Jet actuator in delaying separation in stall region and increasing aerodynamic performance is numerically simulated. The location of the actuator on the airfoil has been studied. In this study, synthetic Jet simulations were performed in three locations of 12, 20 and 30% of the airfoil chord length to identify the optimal location for actuation. The location of 30% of airfoil chord length at all angles of attack was able to provide a higher CL than the maximum CL in the based airfoil. The highest value of the lift can be seen by using the flow control at an angle of attack of 18 degrees with a 6% lift increment compared to the based airfoil. Also, the drag coefficient in the position of 30% of the chord length and the angle of attack of 20 degrees decreased by 26% compared to the based airfoil.

In this work, to comprehensively analyze the flow field characteristics of a normal slot plasma synthetic Jet actuator, three-dimensional simulation models are established for both normal slot and normal orifice actuators. A detailed comparative analysis of the three-dimensional flow field characteristics of these two actuators is performed. The results indicate that the motion shockwaves and Jets generated by the normal slot actuator cover a larger and more uniform region, showing planar characteristics and excellent flow control uniformity. The total pressure ratio for the normal slot actuator is 3.59, significantly higher than the value of 3.50 for the normal orifice actuator, indicating lower pressure loss in the former. Additionally, the normal slot has a larger average exit Mach number (Ma), indicating a stronger flow control capability. It also achieves the peak Ma in a shorter time, indicating a faster momentum output response. Therefore, compared with the normal orifice actuator, the normal slot actuator has better potential for flow control.

After the deflection of the wing control surface, flow separation is easily generated at the trailing edge of the wing, which will reduce the lift coefficient and the control surface efficiency. The rudder of the wing is aileron. If the lift generated by the wing is used to improve the efficiency of the control surface, the flow separation caused by the deflection of the control surface must be restrained. Using synthetic Jet to change the flow state of boundary layer is the main method to solve the problem of flow separation. Synthetic Jet actuator (SJA) has the advantages of no energy loss and simple structure. In this paper, a method of using synthetic Jet actuator to suppress the flow separation at the rear of the wing when the aileron deflects is proposed, and the lift coefficient is obtained. The increase of aileron efficiency is calculated by the change of lift coefficient. The EPPLER555 wing with aileron deflection angle of 3°~9° is simulated, and the changes of lift coefficient and aileron efficiency under corresponding working conditions are obtained. The results show that the average lift coefficient of the wing is 0. 5 when the deflection angle of the aileron is 3°~9° without SJA. After SJA employed, the lift coefficient will be greatly improved, and the control surface efficiency of EPPLER555 wing will be effectively improved, the lift coefficient will increase by about 20% to 0. 6-0. 7. For example, when the deflection angle of aileron is 4°, using a SJA with a maximum outlet velocity of 200m/s and an excitation frequency of 400/2π, the effective lift coefficient generated by the wing is 0. 5931. Under the effect of SJA, the control surface efficiency of EPPLER555 wing will be effectively improved. The lift coefficient is reflected by the ratio of the change of lift coefficient after SJA employed to the lift coefficient without synthetic Jet actuator.

The purpose of this research is to use the artificial Jet actuator to control the boundary layer with the approach of improving the aerodynamic performance of NASA GAW-2 supercritical airfoil in the post-stall region. In this research, unsteady Navier-Stokes equations were solved in turbulent and incompressible flow conditions using Fluent software. In this research, the excitation frequency factor has been studied as a parameter influencing the flow control by the artificial Jet actuator. The results are presented for three dimensionless frequencies 1, 3 and 5. Under the effect of dimensionless frequency 5, the highest increase in the coefficient of attack was obtained for the angle of attack of 18 degrees, which has increased by 10% compared to the maximum for the uncontrolled state. The biggest decrease in the drag coefficient is related to the dimensionless frequency of 5 and the angle of attack of 20 degrees, in which the drag coefficient has decreased by 37% compared to the uncontrolled state. In the best control mode, the separation point is delayed by 25.8% of the chord length.

in this research, their effects on the flight of airplanes were investigated. The study area is the country of Iran, and the flight routes of Kermanshah, Ahvaz and BandarAbbas to Tehran. The research data includes maps of the Vertical Transect (profile) of the Jet stream, the daily average of the Zonal wind (U-Wind) and meridional wind (V-Wind) components for the winter period of 2018 through NOAA/NCEP environmental databases. Also, flight route information was received from FlightRadar24 and Flightaware systems. First, by using Vertical Transect maps, the days containing strong U-Wind were extracted, and the average position of the core of the Jet Streams in the Zonal and meridional wind components, the Tropospheric level of 200 HP was detected. The list of flights was prepared, and the Zonal Wind maps were produced. Finally, the height of the flights was compared with the level of the currents of the Jet Streams, and the influence or lack of influence of the Jet Streams on the flights was studied. According to the results of the research, all the Jet Streams caused turbulence for all flights, and they caused a decrease in the speed of flights between Ahvaz and BandarAbbas to Tehran and an increase in the speed of flights between Kermanshah and Tehran according to the direction and type of Jet Streams. It was also found that all the Jet Streams had a speed of more than 90 knots, so the capacity to create tension and turbulence such as CAT was seen in them

This paper investigates the influence of a weak-Jet on the development of a turbulent axisymmetric strong Jet. A parametric study is carried out to evaluate simultaneously the effect to the Jets-spacing (S/D=3 and S/D=7. 5) and their velocity ratios in range 0≤ λ ≤ 1. The mixing phenomenon is studied numerically by the finite volume method using the 3D-RANS second-order model, which gives a good agreement with the available data. Three distinct regions of this type of Jets interaction are evidenced. This study confirms that the Jets spacing affects strongly the converging region and has a minor effect on the combining region. It is found that the weak Jet attracts the strong Jet and the combining region extends from 30D to 40D where the self-similarity of a single Jet is obtained. The Jet width decreases when velocity ratio and Jets spacing augment. In the combining region, in comparison with the free Jet, it is found that the addition of a weak-Jet increases the decay rate of the centerline velocity.

An actuator is a device that converts input energy into mechanical energy. According to various types of input energy, various actuators have been advanced. Displacement in the electromagnetic, hydraulic and pneumatic actuators achieve by moving a piston via electromagnetic force or pressure, however the piezoelectric actuator (piezoceramic plates) displace directly. Therefore, accuracy and speed in the piezoelectric device are higher than other types of actuators. In the present work, the high-field electromechanical response of high-quality (1−x)(Bi 0.5Na0.5)TiO3–x(Bi0.5K0.5)TiO3 samples abbreviated to BNKTx with x = 0.18, 0.20, 0.22 and 0.24 ceramic materials across its MPB was investigated. The piezoelectrics and actuation characteristics were characterized. Ourresults indicate that x = 0.20, indeed, constitutes the best choice for the MPB composition in the system. Maximum of remanent polarization (37.5 mC cm-2) was obtained for x=0.20. High-field electromechanical responses were also obtained for BNKT0.20 samples. This material exhibited giant field induced strains of 0.13% under 1 kV mm -1 at room temperature.