JP5500997B2 - Plasma actuator - Google Patents

Description

The present invention relates to a plasma actuator, and more particularly to a plasma actuator that can reduce the influence of airflow on plasma.

  In recent years, fluid control using a plasma actuator using dielectric barrier discharge has been actively studied. In the plasma actuator, for example, electrodes are arranged with a dielectric such as resin or ceramic sandwiched between them, and an AC voltage or a pulse voltage is applied between the electrodes to generate plasma near the electrodes on the surface side of the dielectric.

  Such a plasma actuator is attached to the blade of a gas turbine like the thing of patent document 1, for example, and suppresses peeling of the air current in the blade surface. Similarly, Patent Document 2 discloses a plasma actuator used for suppressing separation of airflow. Further, as a plasma actuator used for controlling the separation of the airflow, one that is arranged on the Coanda surface of an aircraft wing in Patent Document 3 is known.

JP 2008-270110 A Special table 2009-511360 gazette JP 2008-290710 A

  By the way, each of the plasma actuators described above is exposed to a high-speed air stream under a high pressure. For this reason, the generated plasma may be caused to flow by such an air flow. As a result, the plasma may become unstable and it may be difficult to control the airflow.

  Therefore, the present invention aims to eliminate such problems.

  In order to achieve such an object, the present invention takes the following measures.

That is, the plasma actuator according to the present invention has three or more electrodes and two or more and one dielectric less than the electrodes, and is arranged on the surface side of the object to apply a high voltage to the electrodes. In this way, the plasma actuator generates plasma at the end of the dielectric that is exposed so as to be in contact with the gas, and the electrodes and the dielectric are alternately stacked. It arrange | positions so that it may be exposed to a normal line direction.

  Here, examples of the high voltage applied to the electrode include a voltage already known to be capable of generating plasma, such as a high-voltage AC voltage or a pulse voltage.

  According to such a configuration, plasma is generated over a plurality of stages by applying a high-voltage AC voltage or a pulse voltage, so that a shock wave accompanying the generation of plasma is also generated over a plurality of stages. As a result, shock waves generated over a plurality of stages are connected to each other, so that a stronger shock wave can be generated. As a result, the effectiveness with respect to the dynamic pressure flow is enhanced, and the gas flow can be controlled even in a high-speed flow under a high pressure.

  As a configuration for more reliably controlling the flow of gas, the ends of the electrodes and the ends of the dielectrics are exposed in the normal direction of the object surface in the stacking order. The dimension which the edge part exposes from an electrode can set what is set larger than the dimension which the edge part of an electrode exposes from a dielectric material.

  According to the present invention, by generating plasma over a plurality of stages, shock waves generated along with the generation of plasma are connected to each other, so that a stronger shock wave can be generated. As a result, it is possible to provide a plasma actuator that is highly effective against dynamic pressure flow and can control the flow of gas even in high-speed flow under high pressure.

Structure explanatory drawing which concerns on the same embodiment. The typical structure explanatory view concerning the embodiment. 1 is an external view according to a first embodiment of the present invention. The partial expanded sectional view. The fragmentary sectional view concerning a 2nd embodiment of the present invention. The partial expanded sectional view. The external view which concerns on the modification of this invention. The partial expanded sectional view concerning the other modification of this invention.

<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 3, the plasma actuator according to this embodiment is mounted on a body surface B of an automobile C. As shown in the figure, in the present embodiment, as an example in which the plasma actuator 1 is mounted, the plasma actuator 1 is mounted on the front end portion of the bonnet on the surface B of the body, the upper portion of the windshield, and the upper portion of the rear glass.

  Here, the plasma actuator 1 according to the present embodiment includes three or more four electrodes 11 and two or more three dielectrics 10, which are arranged on the surface B side of the object. The plasma actuator 1 generates plasma 15 at the end 10a of the dielectric 10 exposed so as to be in contact with gas by applying a high voltage to the electrode 11, and the electrodes 11 and the dielectric 10 are alternately stacked. In addition, the end portions 10a of the dielectrics 10 are arranged so as to be exposed in the normal direction of the object surface B in the stacking order. In each drawing in this specification, the thicknesses of the dielectric 10 and the electrode 11 are exaggerated so that the structure can be clearly understood.

  Hereinafter, the configuration of the plasma actuator 1 will be described with reference to FIGS. 1 to 4.

  As shown in FIGS. 1 and 2, the dielectric 10 is made of three thin plate-like insulators in the present embodiment. The dielectric 10 is made of, for example, a ceramic system such as alumina, zirconia, or silicon nitride, or a polymer system such as Teflon (registered trademark) or polyimide, and has a thickness that hardly resists air.

  The electrode 11 is formed in a thin plate shape as shown in FIGS. The electrode 11 is formed of an electromagnet, which is a magnetic material in this embodiment. The electrode 11 includes an upper electrode 12 positioned at the uppermost portion, a lower electrode 14 positioned at the lowermost portion, and two intermediate electrodes 13 interposed between the upper electrode 12 and the lower electrode 14. These electrodes 11 are arranged in a state of being electrically insulated from the surface B. When the air flow direction is used as a reference, the upper electrode 12, the intermediate electrode 13, and the lower electrode 14 are arranged in this order from the upstream side toward the downstream side. In particular, in the present embodiment, as schematically shown in FIG. 3, in order to generate plasma more efficiently, the upper electrode 12 that is the uppermost electrode is set to a negative pole. The electrodes 11 are arranged such that at least a part of a pair of electrodes 11 arranged via any one of the dielectrics 10 overlaps in plan view.

  Thus, as described above, the plasma actuator according to the present embodiment is configured such that the electrodes 11 and the dielectrics 10 are alternately stacked, and the end portions 10a of the dielectrics 10 are exposed in the normal direction of the surface B in the stacking order. 11 and a stepped exposed portion X in which the dielectric 10 is disposed.

  The stepped exposed portion X is obtained by exposing the end 10a of the dielectric 10 and the end 11a of the electrode 11 in the normal direction of the surface B in the stacking order. Specifically, the stepped exposed portion X is formed so that the end portion a of the electrode 11 and the end portion 10a of the dielectric 10 are inclined from the surface direction of the electrode 11 and the dielectric 10 with respect to the surface B which is the object surface. It arrange | positions so that it may expose continuously. In this embodiment, the dimension α at which the end 10 a of the dielectric 10 is exposed is set to be larger than the dimension β at which the end 11 a of the electrode 11 is exposed from between the dielectrics 10.

  In this configuration, in the present embodiment, a high-voltage pulse voltage is applied between the electrodes 11 when the automobile C as shown in FIG. As a result, as shown in FIGS. 1 and 4, plasma 15 is generated on the surface of the dielectric 10 on the downstream side of the electrode 11. The high-voltage pulse voltage to be applied may be a voltage and frequency known in this field, for example, 1 kV to 10 kV, 1 kHz to 10 kHz, and changeable depending on the flow rate. Of course, in addition to the embodiment shown in FIG. 1, a high voltage AC voltage having the same voltage and frequency may be applied.

  When the voltage is applied to the electrode 11, plasma 15 is generated over a plurality of stages. Shock waves SW are generated from locations where the plasma 15 is generated over a plurality of stages. In the present embodiment, the stepped exposed portion X is arranged so that the positions where the plasma is generated are arranged obliquely, so that the generated shock wave SW is connected in an oblique direction, and a stronger shock wave SW is generated. It has become something that can be. As a result, even a high pressure, high flow rate gas can be reliably controlled.

  In addition, in the state in which a voltage is applied to the electrode 11, the electrode 11 as an electromagnet forms a pulse magnetic field having the same frequency as the applied high-voltage pulse voltage. The pulse magnetic field is generated perpendicular to the surface electrode 11 and covers the generated plasma 15. Thus, when the pulsed magnetic field acts on the plasma 15, ions in the plasma 15 move while spinning in the opposite direction to the direction of the magnetic field, and electrons move while spinning in the same direction with respect to the direction of the magnetic field. . As a result, ions, electrons, and radicals collide with each other in the plasma 15 to promote the generation of the plasma 15, and the plasma 15 is suppressed from moving from the generated position by the formed pulse magnetic field. Is detained in that position. When an AC voltage is applied to the electrode 11 instead of the pulse voltage, an alternating magnetic field is formed instead of the above-described pulse magnetic field.

  When the vehicle C as shown in FIG. 3 is driven with the above voltage applied to the plasma actuator 1, the body surface B of the vehicle C receives wind pressure from the front. At this time, the plasma 15 generated over a plurality of stages in the plasma actuator 1 generates a strong shock wave SW as described above while being restrained from moving by the magnetic field, and thus acts efficiently on the air flowing from the front. As a result, an induced airflow is generated by the plasma actuator 1 at each site where the plasma actuator 1 is installed, and the airflow, that is, the airflow becomes the solid arrow IF in FIG. It is suppressed. Therefore, the air resistance received by the body of the automobile C is effectively reduced. In addition, when airflow separation occurs without applying a voltage to the plasma actuator 1, the flow of air flows without flowing along the surface B as shown by the dotted arrows in FIG. It becomes.

  With the configuration as described above, the plasma actuator 1 according to the present embodiment generates the plasma 15 over a plurality of stages by applying the pulse voltage, so that a plurality of shock waves SW generated along with the generation of the plasma 15 are also generated. Occurs across stages. Therefore, the generated shock waves SW are connected to each other, so that a stronger shock wave SW can be generated even when the same voltage is applied as compared with the conventional one in which the dielectric 10 is configured as a single unit. For this reason, since it becomes possible to control the gas flow even in a high-speed flow under a higher pressure than in the past, it is possible to effectively reduce the air resistance applied when the automobile C is traveling. As a result, the fuel consumption of the automobile C can be improved. In addition, it is possible to effectively reduce the wind noise that occurs when the vehicle C is traveling.

  In other words, since the plasma actuator 1 according to the present embodiment can generate a stronger shock wave SW even at the same voltage as that of the conventional one, the electric power necessary to obtain a flow improvement effect with a required strength. Can be effectively reduced.

  In the plasma actuator 1 according to the present embodiment, the stepped exposed portion X and the end portion 10a of the dielectric 10 and the end portion 11a of the electrode 11 are arranged in the stacking order in order to more reliably control the gas flow. It is assumed that the surface B is exposed in the normal direction, and the dimension α at which the end 10a of the dielectric 10 where the plasma 15 is generated is exposed is set larger than the dimension β at which the end 11a of the electrode 11 is exposed. It is assumed that

Second Embodiment
Hereinafter, the second embodiment of the present invention will be described in detail. In addition, in this embodiment and each modification mentioned later, while attaching the same code | symbol to the component corresponded to the said 1st Embodiment, the detailed description shall be abbreviate | omitted.

  The plasma actuator 1 according to this embodiment is applied to a multi-cylinder engine 100 for an automobile which is an internal combustion engine. The engine 100 is of a spark ignition type using, for example, gasoline as fuel. The engine 100 introduces intake air and fuel into the cylinder 22 via an intake port 21 following the intake manifold. FIG. 4 shows an enlarged configuration of the main part of the one cylinder. Each intake port 21 has a shape that curves from the intake manifold side toward the combustion chamber 23. Each of the intake ports 21 is provided with the plasma actuator 1 at a position on a curved surface 24 that curves in a convex shape toward the inside, where gas separation is likely to occur due to curvature. In FIG. 5, 26 is an intake valve, 27 is an exhaust port, 28 is an exhaust valve, and 29 is a piston.

  In FIG. 6, the thicknesses of the dielectric 10 and the electrode 11 are exaggerated so that the structure can be clearly understood. Actually, the thickness of the entire plasma actuator 1 is a thickness that does not disturb the airflow of the intake air.

  When the engine 100 is operated, intake air flows into the cylinder 22 through the intake port 21 in the intake stroke of each cylinder. At this time, the plasma 15 generated in the plasma actuator 1 acts efficiently on the inflowing intake air as in the above embodiment. As a result, an induced airflow is generated by the plasma actuator 1 at the site where the plasma actuator 1 is installed, and the airflow of the intake air becomes as indicated by the solid arrow IF in FIG. 6 due to the induced airflow, and the separation of the airflow is suppressed. . Therefore, the intake air flows smoothly into the cylinder 22. For this reason, the charging efficiency of intake air can be improved and fuel consumption can be improved. When airflow separation occurs, the airflow of the intake air flows without flowing along the curved surface 24 as shown by a dotted arrow in FIG. .

  Note that the plasma actuator 1 installed in the intake port 21 is not limited to one as in the above-described embodiment, and may be installed at each position where it is estimated that separation occurs in the airflow of the intake air. . That is, depending on the shape of the intake port 1, it may be installed at a plurality of locations in the direction of the airflow of the intake air.

  Although the embodiment of the present invention has been described above, the specific configuration of each unit is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

<Modification>
For example, as shown in FIG. 7, a plasma actuator 1 similar to the above embodiment may be used for the wing W of an airplane. In this case, as shown in the figure, an induced airflow is generated by the plasma actuator 1 as in the above embodiments, and the airflow of the intake air is as shown by the solid arrow IF in FIG. .

  Further, as shown in FIG. 8, the downstream end portion 11a of the electrode 11 and the downstream end portion 10a of the dielectric 10 are aligned at the same position in plan view, and the normal direction of the surface B of the object is viewed from the normal direction. Only the dielectric 10 may be exposed. Even with such a configuration, the same effects as those of the above-described embodiments and modifications can be obtained by generating the plasma 15 over a plurality of stages.

  In addition to the above modifications, for example, in the above embodiment, an electromagnet is employed as the magnetic body, but a permanent magnet may be used. In addition, specific modes such as the dielectric and electrode materials and specific dimensions are not limited to those of the above-described embodiment, and various modes including the existing ones can be applied.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  Examples of the application of the plasma actuator of the present application include those used in places where aerodynamic resistance is generated, such as various internal combustion engines such as spark ignition engines and diesel engines equipped with intake ports, aircraft wings, and automobile exteriors. An example of the use of the internal combustion engine of the present application is an automobile.

DESCRIPTION OF SYMBOLS 1 ... Plasma actuator 10 ... Dielectric 11 ... Electrode 15 ... Plasma X ... Stepped exposure part

Claims (2)

It has three or more electrodes and two or more and one less dielectric than the electrodes, and it can be placed in contact with gas by placing it on the surface side of the object and applying a high voltage to the electrodes A plasma actuator for generating plasma at an exposed end of the dielectric,
A plasma actuator, wherein electrodes and dielectrics are alternately laminated, and the ends of the dielectrics are arranged so as to be exposed in the normal direction of the object surface in the order of lamination.   The end of each electrode and the end of each dielectric are exposed in the normal direction of the surface of the object in the stacking order, and the dimensions at which the end of the dielectric is exposed from the electrode The plasma actuator according to claim 1, wherein the plasma actuator is set to be larger than a dimension exposed from.

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