Plasma actuator

Abstract

To solve the problem in which: a conventional plasma actuator is structured to equally generate an induction air flow at both sides of an exposed electrode and it is difficult to change the air quantity of the induction air flow.SOLUTION: The present invention relates to a plasma actuator A which generates an induction air flow F on a front side face of a dielectric 1 by applying a voltage between a first electrode 11 on the front side face of the dielectric 1 and a second electrode 12 on a rear side face. On a cross section in a flow direction of the induction air flow F, the second electrode 12 is sized to extend in a direction of both ends of the first electrode 11, and the dielectric 1 includes an induction region B which promotes the generation of the induction air flow by changing a dielectric constant at one side of the first electrode 11. The air quantity of the induction air flow F generated at both sides of the first electrode 11 can be changed, and the sufficient induction air flow F is supplied in a specific direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a plasma actuator used in a cooling device, an air flow control device, or the like.

Background Art

[0002] As a conventional plasma actuator, for example, there is one described in Patent Document 1. The plasma actuator described in Patent Document 1 includes an exposed electrode provided on the surface of a dielectric and a second electrode provided inside the dielectric. Then, the plasma actuator generates plasma from both sides of the exposed electrode by applying an alternating voltage to both electrodes, and generates an induced air flow along the surface of the dielectric. In Patent Document 1, the above plasma actuator is arranged on the surface of a heating element and used as a cooling device for the heating element.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since the conventional plasma actuator as described above has a structure that generates an induced air flow evenly on both sides of the exposed electrode, for example, when arranging other components around it, even if it is necessary to avoid interference with that component, there is a problem that it is difficult to change the air volume of the induced air flow generated on both sides of the exposed electrode. Solving such a problem has been an issue.

[0005] The present invention has been made by paying attention to the above conventional problems, and an object of the present invention is to provide a plasma actuator capable of changing the air volume of the induced air flow generated on both sides of the first electrode, which is the above exposed electrode, and supplying a sufficient induced air flow in a specific direction.

Means for Solving the Problem

[0006] The plasma actuator according to the present invention generates an induced air flow on the front surface of a dielectric by applying a voltage between a first electrode disposed on the front surface of the dielectric and a second electrode disposed on the back surface. And, in a cross section along the flow direction of the induced air flow, the second electrode has a size extending in both end directions of the first electrode, and the dielectric has an induced region on one side of the first electrode that promotes the generation of the induced air flow due to a change in the dielectric constant. The induced region includes a void that exposes the second electrode in a plan view, and includes a second dielectric having a dielectric constant higher than that of the dielectric, and the void It is characterized by the above. The above-mentioned induced region is a region that changes the dielectric constant by selecting the material, shape, and size (volume) of the dielectric and promotes the generation of the induced air flow.

Advantages of the Invention

[0007] By adopting the above configuration, the plasma actuator according to the present invention can change the air volume of the induced air flow generated on both sides of the first electrode and supply sufficient induced air flow in a specific direction where the induced region is arranged.

Brief Description of the Drawings

[0008]

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Mode for Carrying Out the Invention

[0009] 〈First Embodiment〉 The plasma actuator A shown in FIG. 1 includes a first electrode 11 disposed on the front surface (the upper surface in the figure) of the dielectric 1 and a second electrode 12 disposed on the back surface of the dielectric 1. The first and second electrodes 11 and 12 are connected to a power source 6 via wirings 4 and 5. The plasma actuator A generates low-temperature plasma from both sides of the first electrode 11 by applying an alternating voltage to both electrodes 11 and 12, and generates an induced air flow F on the surface of the dielectric 1.

[0010] In the cross-section along the flow direction of the induced air flow F, the second electrode 12 has a size that extends in the direction of both ends of the first electrode 11 in the above-described plasma actuator A. And in the plasma actuator A, the dielectric 1 has an induced region B on one side (the right side in the figure) of the first electrode 11 that promotes the generation of the induced air flow F due to a change in the dielectric constant.

[0011] The dielectric 1 is a flat plate-like member and has a size that extends in the direction of both ends of the first electrode 11, similar to the second electrode 12. The material of the dielectric 1 is not particularly limited, and examples thereof include resins such as acrylic, polycarbonate, polyester, polyimide, and fluororesin, dielectrics such as glass, ceramics, and silicone.

[0012] The first and second electrodes 11 and 12 are not particularly limited as long as they are ordinary electrode materials, and various materials can be used, such as copper, nickel, gold, platinum, and aluminum. The first electrode 11 may be arranged on the front surface of the dielectric 1 as shown in the figure, or may have a structure embedded in the dielectric 1 so that the front surfaces are flush with each other.

[0013] Here, the second electrode 12 has a size that extends in both end directions of the first electrode 11, that is, in the direction along the flow of the induced air flow F, a length that is sufficiently larger than the length of the first electrode 11. Such a plasma actuator A is suitable, for example, when used as a cooling device for a heat sink, and as the second electrode 12, a metal member such as a base plate, a fin aluminum plate, etc. that constitutes the heat sink can be employed.

[0014] In the plasma actuator A in this embodiment, the induction region B includes, in a plan view, an end portion of the first electrode 11 and a void E that exposes the second electrode 12. The second electrode 12 has an exposed surface 12A due to the void E. In short, on the side of the dielectric 1 where the induction region B is located, it is shorter than the opposite side, and the shortened portion is used as the void E.

[0015] When an alternating voltage is applied to the first and second electrodes 11 and 12 of the plasma actuator A having the above configuration, low-temperature plasma is generated above the dielectric 1, and the ionized charges are pulled by the electric field directed from the first electrode 11 toward the second electrode, generating an induced flow F.

[0016] At this time, in the plasma actuator A described above, the induced air flow F is generated on the left and right sides of the first electrode 11. In particular, at the exposed surface 12A of the void E in the induction region B, the electric lines of force are not canceled and the electric field does not weaken. Therefore, compared with the opposite side, the charges generated by plasma generation are strongly pulled toward the exposed surface 12A side, and the induced flow F is strongly generated.

[0017] In this way, the plasma actuator A described above can change the air volume of the induced air flow F generated on both sides of the first electrode 11, and can supply sufficient induced air flow F in a specific direction where the induction region B is arranged.

[0018] Also, in the plasma actuator A, for example, when applied to a cooling device, since the heat transfer coefficient of the dielectric 1 is relatively low, it is difficult for heat to be transferred from the second electrode 12 side to the front surface of the dielectric 1, and heat transfer to the induced air flow F is likely to be insufficient. On the other hand, in the plasma actuator A described above, the strongly generated induced air flow F flows to the exposed surface 12A, and since there is no inhibition of heat conduction by the dielectric 1, heat transfer to the induced air flow F can be promoted.

[0019] In this way, if the plasma actuator A uses a metal member such as a base plate, fins, and an aluminum plate that constitute a heat sink as the second electrode 12, the strongly generated induced air flow F can cool the second electrode 2 (metal member) well, so it has high utility value as a cooling device for the heat sink. Also, when the plasma actuator A is used as a cooling device, it is also effective to use a plurality of sets of the dielectric 1 having the induction region B and the first electrode 11 on the second electrode 12 having a sufficient size, and arrange each set in the same direction at a predetermined interval.

[0020] Figs. 2 to 11 are diagrams for explaining the second to eleventh embodiments of the plasma actuator according to the present invention. In the following embodiments, the same reference numerals are given to the same constituent parts as in the first embodiment, and detailed descriptions thereof are omitted. Also, in Figs. 2 to 11, the wirings (4, 5) and the power source (6) shown in Fig. 1 are all omitted.

[0021] <Second Embodiment> The plasma actuator A shown in Fig. 2 includes a second dielectric 2 having a dielectric constant higher than that of the dielectric 1 and a void E (exposed surface 12A). The second dielectric 2 has the same thickness as the dielectric 1 and is arranged continuously at the end of the dielectric 1. As an example, the dielectric 1 is made of a material such as acrylic, polycarbonate, polyimide, and fluororesin with a dielectric constant less than 10. In contrast, the second dielectric 2 is made of a high dielectric constant material with a dielectric constant of 10 to 80 or more.

[0022] Here, the higher the dielectric constant of the dielectric, the larger the capacitance as a capacitor and the larger the withstand voltage on the surface, so the emission intensity of the plasma becomes higher. The plasma actuator A having the above configuration has a higher dielectric constant of the second dielectric 2 than that of the dielectric 1, so the emission intensity of the plasma above the second dielectric 2 becomes higher. As a result, the plasma actuator A as described above can strongly generate an induced current F in the direction of the exposed surface 12A of the second electrode 12, that is, in the direction of the induction region B, and promote heat transfer to the induced air flow F, similar to the first embodiment.

[0023] 〈Third Embodiment〉 The plasma actuator A shown in Fig. 3, similar to the second embodiment, includes a thin portion 1A formed at the end of the dielectric 1, the second dielectric 2 of the second embodiment, and a void E (exposed surface 12A). The thin portion 1A is continuous with the end of the dielectric 1 via a step S that reduces its thickness. In the illustrated example, a thin portion 1A is formed at the end of the dielectric 1 via a step S that descends toward the second electrode 12. And in the induction region B, the second dielectric 2 is laminated on the surface (upper surface) of the thin portion 1A on the side of the first electrode 11. This second dielectric 2 has a thickness corresponding to the height of the step S.

[0024] The plasma actuator A having the above configuration has a thinner second dielectric 2 compared to the second embodiment. However, when the volume of only the second dielectric 2 shown in the second embodiment is equal to the total volume of the laminated portion of the thin portion 1A and the second dielectric 2, the withstand voltage on the second dielectric 2 is higher than the withstand voltage of only the thin portion 1A, so the light emission intensity of the plasma also increases. As a result, the above plasma actuator A can strongly generate the induced flow F with the same stored energy as that of the second embodiment, and can promote heat transfer to the induced air flow F.

[0025] <Fourth Embodiment> The plasma actuator A shown in FIG. 4 includes an induction region B including a second dielectric 2 and a third dielectric 3 having a dielectric constant lower than that of the second dielectric 2, and is structured such that the second dielectric 2, the third dielectric 3, and the void E (exposed surface 12A) are arranged from the first electrode 11 side. Note that the second dielectric 2 has a dielectric constant higher than those of the dielectric 1 and the third dielectric 3, but the magnitude relationship of the dielectric constants of the dielectric 1 and the third dielectric 3 is not particularly limited.

[0026] Since the dielectric constant of the third dielectric 3 of the plasma actuator A having the above configuration is low, the electric field spreads in the direction of the exposed surface 12A of the second electrode 12 while preventing a short circuit, and the charges of the plasma generated above the second dielectric 2 are pulled by the electric field. As a result, the above plasma actuator A, similar to the first embodiment, causes the induced air flow F wind to strongly flow in the direction of the exposed surface 12A of the second electrode 12, and can promote heat transfer to the induced air flow F.

[0027] <Fifth Embodiment> The plasma actuator A shown in FIG. 5 includes an induction region B including a thin portion 1A formed at an end of the dielectric 1 and a void E (exposed surface 12A). Similar to the third embodiment, the thin portion 1A is continuously formed at the end of the dielectric 1 via a downward step S that reduces its thickness toward the second electrode 12 side. The thin portion 1A in the illustrated example has a thickness of about half of the thickness of the dielectric 1, for example.

[0028] The plasma actuator A having the above configuration has a larger capacitance as a capacitor and a higher dielectric breakdown voltage on the surface as the thickness of the dielectric 1 is smaller, so the light emission intensity of the plasma also increases. As a result, the plasma actuator A generates a strong induced air flow F in the direction of the exposed surface 12A of the second electrode 12, similar to the first embodiment, and can promote heat transfer to the induced air flow F.

[0029] <Sixth Embodiment> The plasma actuator A shown in FIG. 6 has an induction region B including an inclined portion 1B formed at an end of the dielectric 1 and a void E (exposed surface 12A). The inclined portion 1B is continuous at the end of the dielectric 1 with a gradient that gradually decreases its thickness. Note that the illustrated inclined portion 1B has a shape in which the thickness continuously decreases due to an inclined surface, but a shape in which the thickness decreases stepwise due to a stepped surface is also included.

[0030] The plasma actuator A having the above configuration generates a strong induced air flow F in the direction of the exposed surface 12A of the second electrode 12, similar to the first embodiment, and can promote heat transfer to the induced air flow F. Further, the above plasma actuator A can cause the induced air flow F to smoothly flow toward the exposed surface 12A of the second electrode 12 particularly due to the inclined surface of the inclined portion 1B, and can further enhance the function of promoting heat transfer to the induced air flow F.

[0031] <Seventh Embodiment> The plasma actuator A shown in FIG. 7 has an induction region B including a thin portion 1A of the dielectric 1, an inclined portion 1B formed at the tip of the thin portion 1A, and a void E (exposed surface 12A). That is, the illustrated plasma actuator A has a structure combining the features of the fifth and sixth embodiments.

[0032] Similar to the first embodiment, the plasma actuator A having the above configuration generates a strong induced air flow F in the direction of the exposed surface 12A of the second electrode 12, and can promote heat transfer to the induced air flow F. Further, the plasma actuator A can further enhance the function of strengthening the induced air flow F and the function of promoting heat transfer to the induced air flow F, particularly by the thin portion 1A and the inclined portion 1B.

[0033] 〈Eighth Embodiment〉 The plasma actuator A shown in FIG. 8 includes a second dielectric 2 thinner than the dielectric 1, a third dielectric 3 disposed at the tip of the second dielectric 2, and a void E (exposed surface 12A), and the third dielectric 3 has a shape inclined downward toward the second electrode 12 side. That is, the illustrated plasma actuator A has a structure combining the features of the fourth to seventh embodiments.

[0034] Similar to the first embodiment, the plasma actuator A having the above configuration generates a strong induced air flow F in the direction of the exposed surface 12A of the second electrode 12, and can promote heat transfer to the induced air flow F. Further, the plasma actuator A can further improve the function of strengthening the induced air flow F and the function of promoting heat transfer to the induced air flow F, particularly by the second dielectric 2 and the third dielectric 3.

[0035] 〈Ninth Embodiment〉 In the plasma actuator A shown in FIG. 9, the induction region B includes the end of the dielectric 1 and the exposed surface 12A of the second electrode 12 in plan view, and the end of the dielectric 1 and the exposed surface 12A are flush on the first electrode 11 side. In the illustrated plasma actuator A, the second electrode 12 has a convex portion 12B toward the first electrode 11 side (upper side in the figure) at a position separated from the first electrode 11. The second electrode 12 has the tip surface (upper end surface) of the convex portion 12B as the exposed surface 12A flush with the dielectric 1.

[0036] Similar to the first embodiment, the plasma actuator A having the above configuration generates a strong induced air flow F in the direction of the exposed surface 12A of the second electrode 12, and can promote heat transfer to the induced air flow F. Further, in the plasma actuator A described above, in particular, since the dielectric 1 and the exposed surface 12A of the second electrode 12 are flush and smoothly continuous, the generated induced air flow F can flow smoothly along the exposed surface 12A of the second electrode 12, and heat transfer to the induced air flow F can be further promoted.

[0037] <〈Tenth Embodiment〉> Similar to the ninth embodiment, the plasma actuator A shown in FIG. 10 has a structure in which the induction region B includes an end portion of the dielectric 1 and the exposed surface 12A of the second electrode 12 in a plan view, and a second dielectric 2 and a third dielectric 3 are interposed between the end portion of the dielectric 1 and the convex portion 12B forming the exposed surface 12A. At this time, the second dielectric 2 is disposed on the end side of the dielectric 1, and the third dielectric 3 is disposed on the convex portion 12B side. The plasma actuator A has a structure in which the induction region B is flush with the surfaces of the first electrodes 11 of the respective dielectrics 1 to 3 and the exposed surface 12A.

[0038] Similar to the first embodiment, the plasma actuator A having the above configuration generates a strong induced air flow F in the direction of the exposed surface 12A of the second electrode 12, and can promote heat transfer to the induced air flow F. Further, in the plasma actuator A described above, in particular, since the induction region B includes the second and third dielectrics 2 and 3, and the front surfaces and the exposed surface 12A of the respective dielectrics 1 to 3 are smoothly continuous, the generation of the induced air flow F is further promoted, the flow of the induced air flow F becomes smooth, and heat transfer to the induced air flow F can be further promoted.

[0039] <〈Eleventh Embodiment〉> The plasma actuator A shown in FIG. 11, similar to the ninth embodiment, has a structure in which the induction region B includes the end of the dielectric 1 and the exposed surface 12A of the second electrode 12 in a plan view. The end of the dielectric 1 has a thin portion 1A via a step S that descends toward the second electrode 12 side. The plasma actuator A has a structure in which the induction region B is flush with the thin portion 1A and the surface of the exposed surface 12B on the side of the first electrode 11.

[0040] The plasma actuator A having the above configuration, similar to the first embodiment, generates a strong induced air flow F in the direction of the exposed surface 12A of the second electrode 12, and can promote heat transfer to the induced air flow F. Further, in the plasma actuator A, since the induction region B has the thin portion 1A of the dielectric 1, the capacitance as a capacitor is large and the light emission intensity of the plasma is also high. Furthermore, in the plasma actuator A, since the front surface of the thin portion 1A and the exposed surface 12A are smoothly continuous, the flow of the induced air flow F also becomes smooth. As a result, the plasma actuator A can further promote the generation of a strong induced air flow F and further promote heat transfer to the induced air flow F.

[0041] As described in each of the above embodiments, the plasma actuator A can change the dielectric constant by selecting the shape, size (volume), and material of the dielectric in the induction region B, and generate a strong induced air flow in a specific direction on the induction region B side.

[0042] The configuration of the plasma actuator according to the present invention is not limited to the above embodiments, and can be appropriately changed without departing from the gist of the present invention, and the configurations of the above embodiments can also be combined.

Explanation of reference numerals

[0043] A Plasma actuator B Induction region E Void F Induced air flow S Step 1 Dielectric 1A Thin portion 1B Inclined Portion 2 Second Dielectric 3 Third Dielectric 11 First Electrode 12 Second Electrode 12A Exposed Surface

Claims

1. A plasma actuator that generates an induced air flow on the front surface of a dielectric by applying a voltage between a first electrode disposed on the front surface of the dielectric and a second electrode disposed on the back surface, wherein: In a cross-section along the flow direction of the induced air flow, the second electrode has a size that extends in both end directions of the first electrode, and The dielectric has an induction region on one side of the first electrode that promotes the generation of an induced air flow due to a change in dielectric constant, The induction region has a void that exposes the second electrode in a plan view, and The plasma actuator is characterized by comprising a second dielectric having a dielectric constant higher than that of the dielectric and the void.

2. The induction region includes a thin portion formed at an end of the dielectric, the second dielectric, and the void, The thin portion is continuous with the end of the dielectric via a step that reduces its thickness, and The plasma actuator according to claim 1, wherein the second dielectric is laminated on the surface of the thin portion on the first electrode side.

3. The induction region includes the second dielectric and a third dielectric having a dielectric constant lower than that of the second dielectric, and the second dielectric, the third dielectric, and the void are arranged in this order from the first electrode side. The plasma actuator according to claim 1, characterized in that.

4. The plasma actuator according to any one of claims 1 to 3, wherein the second electrode is a metal member constituting a heat sink.

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