JP6421296B2 - Plasma actuator - Google Patents

Description

  The present invention relates to an improvement in a plasma actuator that provides a surface electrode and a back electrode on both surfaces of an insulating layer, and generates a plasma from the periphery of the surface electrode by applying a voltage to both electrodes to control a gas flow such as air. Is.

Conventionally, various actuators have been developed, and among them, plasma actuators have attracted attention. As this type of plasma actuator, for example, as shown in FIG. 13, a sheet-like insulator 151 having a surface electrode 152 and a back electrode 153 provided on both sides of a flat insulator 151 such as resin or ceramic as a dielectric is sandwiched. There are known plasma actuators.
The plasma actuator shown in FIG. 13 connects a plasma electrode 156 from the edge 155 of the surface electrode 152 along the surface of the insulator 151 by connecting an AC power source 154 to the front electrode 152 and the back electrode 153 and generating an AC electric field. Is generated.
In particular, the surface plasma generated in this way induces ambient gas to generate an induced airflow 157. Therefore, studies have been made to effectively use this action for wing lift control and the like. In addition, as a device for preventing separation and turbulence of various equipment using fluid flow, and for various application fields such as propulsion sources for flying objects in space, this actuator has no moving parts, is compact Its development has been promoted focusing on characteristics such as being lightweight (see Patent Documents 1 to 4).

However, in such a plasma actuator, there is a problem that a sufficient induced air velocity cannot be obtained as compared with an applied voltage such that a high voltage needs to be applied when the induced air velocity is increased.
Therefore, a plasma actuator has been proposed in which the speed of the induced airflow is improved for the purpose of improving the fluid control performance as shown in Patent Document 5. Specifically, in Patent Document 5, as shown in FIG. 14, a pair of an upper electrode 221 and a lower electrode 222 and a dielectric 223 sandwiched between these electrodes 221 and 222 are used as elements, and both electrodes 221 are included. , 222, a plurality of units 202 that generate plasma when a high-voltage AC voltage or pulse voltage is applied between them are arranged intermittently, and the upper electrode 221 of each unit 202 is adjacent to the unit 202. A plasma actuator is described in which a shielding portion 203 that inhibits plasma generation is provided between the lower electrode 222 of another unit 202.

JP 2010-61919 A

JP 2008-270110 A

JP 2009-242172 A

JP 2008-159336 A

JP 2012-38587 A

However, although the plasma actuator according to Patent Document 5 has a plurality of plasma actuator units connected to each other, it has a slight air velocity increase effect, but it is still not a sufficient increase effect, and a voltage is applied to each of the plurality of units. There is also a problem that since the power consumption is large because it is necessary, the point that the power consumption must be increased in order to increase the airflow speed has not been solved.
In short, there is a demand for the development of a practical plasma actuator that can increase the speed of the induced airflow without increasing the power consumption and can be used for various purposes.

  Therefore, an object of the present invention is to provide a practical plasma actuator that can increase the speed of the induced airflow without increasing the amount of power consumption and can be utilized for various applications.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention thought that the plasma should have been generated only in the direction in which the airflow is generated, and that the plasma was generated in a direction different from the direction in which the airflow was generated. However, we found that the velocity of the induced airflow increased. That is, in the plasma actuator described in Patent Document 5, although a thin wire is used as the surface electrode, the side of the thin wire on both sides thereof is such that plasma is not generated from the side edge opposite to the direction in which the airflow is generated. The edge is coated. Thus, in the past, it was common knowledge that plasma should be generated only in the direction in which airflow is generated in order to ensure the airflow velocity. However, as a result of the study, the inventors have reversed the direction in which airflow is generated. It has been found that the velocity of the airflow may increase even when plasma is generated in the direction, and the present invention has been completed.

That is, the present invention provides the following inventions.
1. A surface electrode is provided on the surface of the plate-like insulating material and on one end side of the insulating material, a plate-like back electrode is provided on the back surface of the insulating material and on the other end side of the insulating material, and a pulse voltage is applied between both electrodes. In the plasma actuator that generates plasma from the surface electrode to generate an induced air current,
The surface electrode is provided with a plasma generating portion in addition to the one side edge so that the surface area of the portion for generating plasma is larger than the area of the one side edge of the surface electrode, And an electric field for charging the gas in the airflow from the periphery of the surface electrode on the upstream side of the induced airflow generated by the plasma. .
2. 2. The surface electrode is formed by providing one or a plurality of fine wires having a width of 0.03 to 0.15 mm, and both side edges of the fine wires are the plasma generating portions. Plasma actuator.
3. 3. The plasma actuator according to 2, wherein the surface electrode is composed of a plurality of the fine wires, and the interval between the fine wires is 0.5 to 2 times the width of the fine wires.
4). The surface electrode is composed of a porous plate-like body in which pores having a diameter of 10 to 150 μm are provided so that the porosity is R0.001 ≦ R ≦ 0.8, and the pores are formed in the plasma generating portion. 2. A plasma actuator according to one aspect.
5. The front surface electrode is disposed on one end side of the insulating material, the back surface electrode is disposed on the other end side of the insulating material, and the first side located on the other end side of the insulating material in the front surface electrode 2. The plasma actuator according to 1, wherein the edge portion is arranged so as not to be positioned on the back electrode.

  The plasma actuator of the present invention can increase the speed of the induced airflow without increasing the amount of voltage, and is practical for use in various applications.

FIG. 1 is a perspective view showing the entire plasma actuator of the present invention. FIG. 2 is an arrow view (side view) of the plasma actuator shown in FIG. FIG. 3 is a side view (corresponding to FIG. 2) showing another embodiment of the plasma actuator of the present invention. FIG. 4 (a) is a side view showing another embodiment of the plasma actuator of the present invention (corresponding to FIG. 2), and FIG. 4 (b) is an enlarged perspective view showing only the surface electrode. FIG. 5 is a side view (corresponding to FIG. 2) showing another embodiment of the plasma actuator of the present invention. FIG. 6 is a side view (corresponding to FIG. 2) showing a plasma actuator as a comparative example. FIG. 7 is a diagram showing an example of an experimental apparatus for measuring the plasma obtained by the plasma actuators obtained in the respective examples and comparative examples, the induced airflow generated thereby, and the velocity thereof. FIG. 8 is a velocity distribution diagram of airflow around the plasma in the first embodiment. FIG. 9 is a velocity distribution diagram of airflow around the plasma in the second embodiment. FIG. 10 is a velocity distribution diagram of airflow around the plasma in the third embodiment. FIG. 11 is a velocity distribution diagram of airflow around the plasma in the fourth embodiment. 12 is a velocity distribution diagram of airflow around the plasma in Comparative Example 1. FIG. FIG. 13 is a schematic view showing a conventional plasma actuator. FIG. 14 is a schematic view showing a conventional plasma actuator.

Hereinafter, the present invention will be described in detail with reference to the drawings.
The plasma actuator of the present invention will be described.
<Overall configuration>
As shown in FIGS. 1 and 2, the plasma actuator 1 as the first embodiment of the present invention has a surface electrode 20 on the surface of a plate-like insulating material 10 and one end 12 side of the insulating material, and a back surface of the insulating material 10. In addition, this is a plasma actuator in which a plate-like back surface electrode 30 is provided on the other end 11 side of the insulating material, and plasma is generated from the surface electrode 20 by applying a pulse voltage between both electrodes to generate an induced air current.
More specifically, as shown in FIGS. 1 and 2, in the plasma actuator 1 of the present embodiment, the insulating material 10 is a rectangular plate-like body so that an induced airflow is generated in the longitudinal direction. A front electrode 20 and a back electrode 30 are arranged. The front electrode 20 is formed by a single thin line, and the back electrode 30 is a rectangular plate-like body. The front surface electrode 20 and the back surface electrode 30 are connected to a power source 50 via electric wires 40 as shown in FIG. Further, the surface electrode 20 is disposed on the one end 12 side of the insulating material 10, and the back electrode 30 is disposed on the other end 11 side of the insulating material 10, and is positioned on the other end 11 side of the insulating material 10 in the surface electrode. The one side edge portion 21, that is, the plasma generation portion 25 that generates plasma is arranged so as not to be positioned on the back electrode 30 when the plasma actuator of this embodiment is viewed from the side as shown in FIG. 2. Thus, by forming the plasma generation unit 25 so as not to be positioned on the back electrode 30, the speed of the induced airflow can be further improved.

The surface electrode 20 has a plasma generating portion 25 in addition to the one side edge portion 21 so that the surface area of the portion that generates plasma is larger than the area of the one side edge portion 21 (plasma generating portion 25) of the surface electrode. Is provided. That is, in a normal plasma actuator, the portion that generates plasma is formed to be only one side edge portion 21, but in this embodiment, the portions other than the one side edge portion 21 also generate plasma. The other side edge portion 22 is also a plasma generating portion 25.
Thus, in order to provide a useful plasma generating part that functions to increase the speed of the induced airflow in addition to the one side edge part, one side is located at a site separated by a distance of 0.15 mm or less from the one side edge part. It is preferable to provide a plasma generator other than the edge so that the plasma generated on both sides can be prevented from interfering with each other or canceling out. The lower limit can be set to several μm. However, it is more preferable that the distance is in the range of 0.03 to 0.15 mm from the viewpoint of strength, life and manufacturing simplicity.
As a result, plasma is generated between the plasma generating part formed by the side edges and the back electrode, and at the upstream side of the generated induced air current, that is, in the vicinity of the surface electrode, An electric field for charging a gas such as oxygen or nitrogen is generated. Although such a function itself is the same as that of a conventionally known plasma actuator, the plasma actuator of the present invention is considered to have high efficiency, electric field strength, or electric lines of force, and will be described in detail in the embodiments described later. Thus, the induced airflow can be generated at a higher speed than the conventional plasma actuator.

(Forming material)
As a material for forming the insulating material 10, an insulating material such as a resin such as polyester, polyimide, acrylic, or Teflon (registered trademark), glass, ceramic, or sapphire (glass) can be used.
The size of the insulating material 10 is not particularly limited, and can be various sizes depending on the size of the desired plasma actuator and the applied voltage. For this reason, the thickness is preferably 0.025 mm to 0.1 mm per 1 kV of applied voltage from the viewpoint of favorably generating plasma.

As the material for forming the front electrode 20 and the back electrode 30, various materials can be used without particular limitation as long as they can form a normal electrode, but copper, nickel, gold, platinum, aluminum, ITO, etc. can be used. . Further, these thicknesses are preferably 10 to 50 μm from the viewpoint of generating plasma favorably.
The width w of the thin wire constituting the surface electrode is preferably 0.01 to 20 mm from the viewpoint of effectively generating plasma from both side edges and improving the speed of the induced airflow, and is preferably 0.03 to 0.15 mm. More preferably.

<Manufacturing method>
The plasma actuator of the present embodiment is formed by forming the insulating material into a sheet-like molded article having the above-described preferable thickness by using a known technique, and then known at predetermined positions on the front and back surfaces of the obtained insulating material. It can be obtained by applying an electrode material using a printing method to form a front electrode and a back electrode having a predetermined shape. As the printing method, an EB drawing method or an ion plating method can be used in addition to a known etching method.

<How to use>
The plasma actuator 1 of the present embodiment can be used by applying a voltage from the power source 50 to the front electrode 20 and the back electrode 30 via the electric wire 40 by arranging the plasma actuator 1 in a desired position of a desired device.
Thereby, the plasma p1 and p2 shown in FIG. 2 are generated from the one side edge 21 and the other side edge 22 which are the plasma generation parts 25 of the surface electrode 20, and an induced air current in the arrow direction is generated. As shown in FIG. 2, the plasma p <b> 1 generated from the one side edge 21 side is larger than the plasma p <b> 2 generated from the other side edge 22. Although the mechanism by which the speed of the airflow is increased is not clear, there is a distance (the above-mentioned preferable separation distance range) in which the interaction between the plasma p1 and the plasma p2 occurs. It is thought that the airflow is accelerated.
The voltage applied when used in this way is preferably 3 kVp-p to 100 kVp-p. Moreover, it is preferable that the applied voltage is an alternating current, and it is preferable to apply a bipolar or monopolar alternating voltage, and an alternating voltage crossing 0V is more desirable.

<Second to Fourth Embodiments>
Next, a second embodiment of the present invention will be described. In the following description, differences from the above-described first embodiment will be mainly described, and description of portions that overlap with the first embodiment will be omitted. For this reason, different reference numerals are given to parts different from those in the above-described embodiment, but the same parts are assigned the same numbers. For the points that are not particularly described, the description in the first embodiment is applied as appropriate.

In the plasma actuator 1a of the second embodiment shown in FIG. 3, the surface electrode 21a is composed of three fine lines 21a-1, 21a-2, and 21s-3, and the distance d between the fine lines (at the plasma generating portion in each fine line). The interval between each one side edge with respect to a certain one side edge) is preferably 1.5 to 2.5 times the width of the thin line.
By arranging a plurality of thin wires as surface electrodes in this way, the speed of the induced airflow can be improved more than when only one wire is provided. The number of thin wires installed is three in the present embodiment, but may be two or four or more.

In the plasma actuator 1b of the third embodiment shown in FIG. 4, the surface electrode 21b is preferably a circular pore 26b having a diameter of preferably 10 to 150 μm, more preferably a porosity R 0.001 ≦ R ≦ 0.8, more preferably Is a porous plate-like body provided so that 0.1 ≦ R ≦ 0.8, and one side edge is a plasma generating portion, and the pores 26b are plasma generating portions.
Here, the porosity R is (total area of pores) / (total area of electrodes). The area of the pores means the area of the circular part shown in the figure of the pores 26b shown in FIG. 4, and the total area of the electrodes means the area of the rectangular part of the surface electrode shown in FIG.
Further, in the present embodiment, an example in which the pores 26b are provided equally for convenience of illustration is shown, but the present invention is not limited to this example, and the pores may be arranged unevenly.
The width wb of the surface electrode in the present embodiment can be made thicker than the thin line, but it is preferably 0.015 to 3 mm because the electrode is easily damaged when it becomes too thin.
In addition, it is preferable that the positions where the pores are provided be not so far from one side edge, but the electrodes may be provided to the full width as long as it is within the range of the width and thickness of the electrode.

In the plasma actuator 1c of the fourth embodiment shown in FIG. 5, a plurality of surface electrodes 21c are provided with an interval d (same as d in the second embodiment). The thin wire 20 c-1 positioned closest to the other end of the insulator is positioned on the back electrode 30.
When the front surface electrode is constituted by a plurality of thin wires in this way, even if a part of the surface electrode is located on the back surface electrode, a higher air velocity can be obtained as compared with the plasma actuator having the conventional configuration.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, the surface electrode and the back electrode can be coated within a range that does not inhibit the generation of plasma.
The shape of the pores can be various shapes such as a square shape, a hexagonal shape, a rhombus shape, an elliptical shape, and a linear shape in addition to a circular shape.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not restrict | limited to these at all.

[Example 1]
A plasma actuator having a surface electrode formed by a single thin wire shown in FIGS. 1 and 2 with the following forming materials and sizes was produced.
Insulating material: forming material [Teflon (registered trademark)], thickness 100 μm
Surface electrode: forming material (copper), width w 0.1 mm, thickness 17 μm (1/2 ounce)
Back electrode: forming material (copper), width 10 mm, thickness 17 μm

[Example 2]
A plasma actuator in which a surface electrode was formed by the three thin wires shown in FIG.
Insulating material: forming material [Teflon (registered trademark)], thickness 100 μm
Surface electrode: forming material (copper), width w 0.1 mm, interval d 0.25 mm, thickness 17 μm
Back electrode: forming material (copper), width 10 mm, thickness 17 μm

Example 3
A plasma actuator in which the porous surface electrode shown in FIG. 4 was formed with the following forming materials and sizes was prepared.
Insulating material: forming material [Teflon (registered trademark)], thickness 100 μm
Surface electrode: forming material (copper), average diameter 150 μm, density 12 / mm ² , thickness 17 μm
Back electrode: forming material (copper), width 10 mm, thickness 17 μm
(Porous part on the surface electrode)

Example 4
A plasma actuator in which a surface electrode is formed by the three thin wires shown in FIG.
Insulating material: forming material [Teflon (registered trademark)], thickness 100 μm
Surface electrode: forming material (copper), width w 0.1 mm, thickness 17 μm
Back electrode: forming material (copper), width 10 mm, thickness 17 μm

[Comparative Example 1]
A conventionally known plasma actuator shown in FIG. 6 was prepared with the following forming materials and sizes.
Insulating material: forming material [Teflon (registered trademark)], thickness 100 μm
Surface electrode: forming material (copper), width w5 mm, thickness 17 μm
Back electrode: forming material (copper), width 10 mm, thickness 17 μm

[Test example]
With respect to each of the obtained plasma actuators, the generation of plasma and the generation of airflow were examined using the apparatus shown in FIG. 7, and the velocity of the airflow was measured. The measuring method was performed according to the method described in JP-A 2010-61919 [0012]. Moreover, about the speed of the airflow, the speed of each example was evaluated on the basis of the comparative example 1. The applied voltage was AC ± 2.5 kV (5.0 kVp-p).
The results are shown in FIGS.
As is apparent from the results shown in FIGS. 8 to 12, the plasma actuators of the present invention all have a higher airflow speed than the conventional ones even though the same voltage is applied. In particular, it can be seen that the plasma actuator of Example 2 in which three fine wires are arranged is twice as fast as the conventional one, and is particularly effective.

  The plasma actuator of the present invention can be used for various applications, and is particularly useful for improving energy energy efficiency, reducing noise, etc. in automobiles, airplanes, and windmills.

DESCRIPTION OF SYMBOLS 1 Plasma actuator, 10 Insulating material, 20 Front surface electrode, 30 Back surface electrode, 50 Power supply, P1, P2 plasma, 25 Plasma generation part

Claims (1)

A surface electrode is provided on the surface of the plate-like insulating material and on one end side of the insulating material, a plate-like back electrode is provided on the back surface of the insulating material and on the other end side of the insulating material, and a pulse voltage is applied between both electrodes. In the plasma actuator that generates plasma from the surface electrode to generate an induced air current,
The surface electrode is provided with a plasma generating portion in addition to the one side edge so that the surface area of the portion for generating plasma is larger than the area of the one side edge of the surface electrode, And generating an electric field that charges the gas in the airflow from the periphery of the surface electrode on the upstream side of the induced airflow generated by the plasma.
Said surface electrode has a width which is formed by a is and cross-sectional shape provided in parallel three Zeng respectively a rectangular thin lines 0.03 to 0.15 mm, both side edges the plasma Said sub line Generating part,
The back electrode is a rectangular plate, and only one is arranged ,
The front electrode and the back electrode have the same length and are arranged in parallel, respectively, and the plasma generating part in the front electrode is arranged in parallel with the longitudinal direction of the back electrode,
The front surface electrode is disposed on one end side of the insulating material, the back surface electrode is disposed on the other end side of the insulating material, and other than the insulating material in the front surface electrode located closest to the back surface electrode side. The one side edge portion located on the end side is disposed so as to be positioned vertically above the side edge of the back surface electrode located on one end side of the insulating material and not on the back surface electrode ,
The plasma actuator, wherein a distance between the thin wires in the surface electrode is 1.5 to 2.5 times a width of the thin wires .

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