JP2013236995A - Air current generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air current generating device which can accelerate a flow rate of a generated induced flow while suppressing a voltage to be applied to a pair of electrodes which generates dielectric barrier discharge.SOLUTION: An air current generating device 10 includes: a dielectric body 20; a first electrode 21 provided on a surface 20a of the dielectric body 20; a second electrode 22 provided, via a dielectric body F, at a position away from the surface 20a of dielectric 20 more than the first electrode 21 and also a position shifted from the first electrode 21 in a direction an inductive flow F flows; and a third electrode 23 provided, via the dielectric body 20, at a position shifted from the second electrode 22 in the direction the inductive flow F flows and on the surface 20a of the dielectric body 20. A discharge power supply 40 that applies an alternating voltage between the first electrode 21 and the second electrode 22, and an acceleration power supply 41 that applies a voltage between the second electrode 22 and the third electrode 23 are included. The inductive flow F is generated from the first electrode side toward the third electrode side.

Description

  Embodiments described herein relate generally to an airflow generation device.

  In fluid equipment and fluid equipment systems, it is necessary to reduce power from the viewpoint of energy saving. In addition, it is necessary to suppress vibration and noise caused by fluid equipment and fluid equipment systems from the viewpoint of ensuring plant safety and improving the work environment.

  In order to satisfy the above-described needs, studies have been made to provide a fluid device or a fluid device system with an air flow generation device that generates a gas flow by converting the fluid into plasma.

  According to this airflow generation device, it is possible to generate a very thin layered induced flow on a flat plate while appropriately controlling it. This generated induced flow realizes airflow control such as changing the velocity distribution in the boundary layer of the flow, forcibly causing a transition from laminar flow to turbulent flow, and generating or extinguishing vortices. Can do. Therefore, there is a possibility that this airflow generation device can be used as an innovative elemental technology for various industrial equipment.

  In the above-described airflow generation device, a pair of electrodes including the first electrode and the second electrode are arranged apart from each other with a dielectric interposed therebetween. A sine wave voltage having an effective value of about 1 to 10 kV and a frequency of about 1 to 100 kHz is applied between the first electrode and the second electrode. Thereby, the air on the surface of the dielectric near the first electrode is turned into plasma, and an induced flow along the surface of the dielectric is generated from the first electrode side toward the second electrode side.

JP 2007-317656 A JP 2008-1354 A

  However, in the above-described airflow generation device, the flow velocity of the induced flow generated is about 3 m / s at the maximum. When the airflow generation device is provided in a wind turbine blade, for example, when the Reynolds number increases due to an increase in the chord length (blade cord length) or the increase in the main flow velocity of the wind, it is necessary to increase the flow velocity of the induced flow. . For this purpose, for example, it is necessary to increase the voltage applied between the pair of electrodes.

  In order to increase the voltage applied between the pair of electrodes, it is necessary to increase the size of the power source. Further, when the voltage applied between the pair of electrodes is increased, the wear of the electrodes and the dielectric due to the discharge plasma is promoted.

  The problem to be solved by the present invention is to provide an air flow generation device capable of accelerating the flow velocity of the induced flow generated while suppressing the voltage applied to the pair of electrodes that cause dielectric barrier discharge. .

  The airflow generation device of the embodiment is an airflow generation device that generates an induced flow. The airflow generator includes a solid dielectric, a first electrode provided on the surface of the dielectric, or embedded near the surface of the dielectric, and the dielectric more than the first electrode. A second electrode provided between the first electrode and the first electrode at a position away from the surface and shifted from the first electrode in a direction in which the induced flow flows. A third electrode provided at a position shifted from the second electrode in the direction in which the induced flow flows and on the surface of the dielectric with the second electrode interposed between the second electrode and the second electrode; Prepare.

  Furthermore, the airflow generation device includes a first voltage application mechanism that applies an alternating voltage between the first electrode and the second electrode, and a gap between the second electrode and the third electrode. A second voltage application mechanism for applying a voltage. Then, the induced flow flows on the surface of the dielectric from the first electrode side toward the third electrode side.

It is the perspective view which showed typically the airflow generator of embodiment. It is a figure which shows typically the AA cross section of FIG. 1 by which the airflow generator of embodiment was shown. It is a figure which shows the other structure of the airflow generation device 10 of embodiment, and shows typically the cross section equivalent to the AA cross section of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view schematically showing an airflow generation device 10 according to the embodiment. FIG. 2 is a diagram schematically showing the AA cross section of FIG. 1 in which the airflow generation device 10 of the embodiment is shown. In FIGS. 1 and 2, the generated induced flow F is indicated by an arrow.

  As shown in FIGS. 1 and 2, the airflow generation device 10 includes a dielectric 20, a first electrode 21, a second electrode 22, and a third electrode 23.

  The dielectric 20 is a known solid dielectric material, and is configured in, for example, a flat plate shape or a film shape. Specific examples of the material constituting the dielectric 20 include an electrically insulating material such as an inorganic insulator such as alumina, glass, and mica, and an organic insulator such as polyimide resin, silicone resin, and synthetic rubber. In addition, the material which comprises the dielectric material 20 is not restricted to these, According to the use and environment where the airflow generation apparatus 10 is used, it can select from a well-known solid dielectric material suitably.

  In order to make the velocity distribution of the induced flow F to be generated uniform, at least one surface 20a of the dielectric 20 provided with the first electrode 21 and the third electrode 23 is preferably a flat surface.

  As shown in FIGS. 1 and 2, the first electrode 21 is provided on one surface 20 a of the dielectric 20. Here, a configuration in which the surface of the first electrode 21 is located on the same plane as the one surface 20 a of the dielectric 20 is shown. The first electrode 21 may be embedded in the dielectric 20 so as to be positioned in the vicinity of one surface 20a of the dielectric 20. Further, the first electrode 21 may be arranged so that at least a part of the first electrode 21 protrudes from the one surface 20a of the dielectric 20 to an extent that does not hinder the airflow flowing on the first electrode 21. Good.

  The first electrode 21 is composed of a conductive member such as a thin plate or a foil, for example. As a conductive member, a well-known conductive material can be used according to the use and environment where the airflow generator 10 is used. For example, the first electrode 21 may be formed by coating one surface 20 a of the dielectric 20 with a conductive member such as copper, gold, nickel, tungsten, or platinum.

  The second electrode 22 is located farther from the one surface 20a of the dielectric 20 than the first electrode 21 and is displaced from the first electrode 21 in the direction in which the induced flow F flows. A dielectric 20 is provided between the electrode 21 and the electrode 21. That is, as shown in FIG. 2, the second electrode 22 is embedded at a position deeper from one surface 20 a of the dielectric 20 than the first electrode 21, for example. Further, the second electrode 22 is arranged in a direction in which the induced flow F flows from the first electrode 21 so that the second electrode 22 does not entirely overlap with the first electrode 21 when viewed from the one surface 20a side of the dielectric 20. The first electrode 21 is spaced from the first electrode 21. Here, the distance between the first electrode 21 and the second electrode 22 is set so that no direct discharge occurs.

  Note that the second electrode 22 is shifted from the first electrode 21 in the flow direction of the induced flow F so as not to overlap the first electrode 21 when viewed from the one surface 20a side of the dielectric 20. May be arranged. The second electrode 22 may be provided on the other surface 20b of the dielectric 20 when the thickness of the dielectric 20 is thin, for example. The second electrode 22 is paired with the first electrode 21 to form a pair of electrodes for generating a dielectric barrier discharge.

  Similar to the first electrode 21, the second electrode 22 is composed of a conductive member such as a thin plate or a foil. Further, the conductive member used is the same as the conductive member used for the first electrode 21.

  The third electrode 23 is located at a position shifted from the second electrode 22 in the direction in which the induced flow F flows, and on the one surface 20 a of the dielectric 20 via the dielectric 20 between the second electrode 22. Is provided. That is, as shown in FIG. 2, the third electrode 23 is arranged such that, for example, the second electrode 22 does not completely overlap with the second electrode 22 when viewed from the one surface 20 a side of the dielectric 20. It is arranged on the surface 20 a of the dielectric 20 so as to be shifted from the direction 22 in which the induced flow F flows, and is separated from the second electrode 22. Here, the distance between the second electrode 22 and the third electrode 23 and the distance between the first electrode 21 and the third electrode 23 are such that no direct discharge occurs between the respective electrodes. Is set to

  The third electrode 23 is shifted from the second electrode 22 in the flow direction of the induced flow F so as not to overlap the second electrode 22 when viewed from the one surface 20a side of the dielectric 20. May be arranged. Here, a configuration is shown in which the surface of the third electrode 23 is positioned on the same plane as the one surface 20 a of the dielectric 20. For example, the third electrode 23 is disposed so that at least a part of the third electrode 23 protrudes from the one surface 20a of the dielectric 20 to an extent that does not hinder the airflow flowing on the third electrode 23. May be.

  Here, the third electrode 23 and the first electrode 21 will be described in detail later, but a dielectric between the first electrode 21 and the second electrode 22 due to an electric field formed between these electrodes. It functions as an electrode for accelerating charged particles generated on one surface 20a of the dielectric 20 by the barrier discharge.

  The third electrode 23 is composed of a conductive member such as a thin plate or a foil, like the first electrode 21. Further, the conductive member used is the same as the conductive member used for the first electrode 21.

  As shown in FIG. 1, the first electrode 21 and the second electrode 22 are connected to a discharge power source 40 that functions as a first voltage application mechanism via cables 30 and 31. The second electrode 22 and the third electrode 23 are connected to an acceleration power supply 41 that functions as a second voltage application mechanism via cables 32 and 33. Here, one cable 34 having one end connected to the second electrode 22 is branched on the other end side to constitute a cable 31 and a cable 33. The side connected to these cables 31 and 33 is, for example, a ground potential.

  The discharge power supply 40 is a power supply for applying an alternating voltage, and outputs a voltage having a pulse-like (eg, AC pulse such as a square) or an AC-like (eg, sine wave, intermittent sine wave) waveform. The discharge power supply 40 applies a voltage between the first electrode 21 and the second electrode 22 by changing current voltage characteristics such as a voltage value, a basic frequency, a current waveform, a modulation frequency, and a duty ratio. be able to.

  The acceleration power supply 41 is constituted by, for example, a power supply that applies a DC voltage between the second electrode 22 and the third electrode 23. In this case, for example, the third electrode 23 is connected to the negative terminal. The acceleration power supply 41 can apply a voltage between the second electrode 22 and the third electrode 23 by changing a current-voltage characteristic such as a voltage value. For example, the acceleration power supply 41 can supply a DC voltage continuously or intermittently.

  Here, for example, the second electrode 22 is arranged so that no direct discharge occurs between the first electrode 21 and the third electrode 23 and between the second electrode 22 and the third electrode 23. The voltage applied between the first electrode 21 and the third electrode 23 is preferably smaller than the voltage applied between the first electrode 21 and the second electrode 22.

  Further, by adjusting the voltage applied by the discharge power supply 40 and the acceleration power supply 41, the potential of the third electrode 23 is set to be smaller than the potential of the first electrode 21. As a result, an electric field is formed in the direction from the first electrode 21 toward the third electrode 23. Therefore, the charged particles having positive charges in the plasma generated by the dielectric barrier discharge between the first electrode 21 and the second electrode 22 are accelerated in the direction from the first electrode 21 toward the third electrode 23. Is done. As a result, the induced flow is accelerated in the direction from the first electrode 21 to the third electrode 23.

  Here, the airflow generation device 10 is installed in, for example, a fluid device. Although it does not specifically limit as a fluid apparatus, For example, aero parts, such as a windmill blade of a wind power generator, a wing of an aircraft, a rear wing spoiler of an automobile, etc. are mentioned. By providing the air flow generation device 10 in these fluid devices, it is possible to control the air flow flowing through the fluid device by the generated induced air flow, thereby reducing power in the fluid device and suppressing vibration and noise.

  Next, the operation of the airflow generation device 10 will be described.

  When a voltage (for example, 1 to 10 kV, frequency 1 to 100 Hz) is applied between the first electrode 21 and the second electrode 22 by the discharge power supply 40 and the potential difference becomes a certain threshold value or more, the first electrode A discharge is induced between 21 and the second electrode 22. This discharge is called dielectric barrier discharge, and low temperature plasma is generated. Due to this discharge, charged particles are deposited on one surface 20 a of the dielectric 20 between the first electrode 21 and the second electrode 22.

  By applying a voltage between the second electrode 22 and the third electrode 23, an electric field is formed between the first electrode 21 and the third electrode 23. For example, a positive charge is generated. The charged particles are accelerated in a direction from the first electrode 21 toward the third electrode 23. Thereby, the induced flow F from the first electrode 21 toward the third electrode 23 can be generated, and the induced flow F can be accelerated.

  Here, an electric field for accelerating charged particles on the surface 20a of the dielectric 20 is also formed between the first electrode 21 and the second electrode 22 simultaneously with the generation of the low temperature plasma. However, after the charged particles are sufficiently generated, the potential of the surface 20a of the dielectric 20 becomes the same as the potential of the first electrode 21, the discharge self-extinguishes, and the first electrode 21 and the second electrode 20 The electric field between the electrodes 22 almost disappears. Therefore, the force acting on the charged particles existing on the surface 20a of the dielectric 20 is lost, and the induced flow F is not generated after self-extinguishing.

  However, as described above, by forming an electric field between the first electrode 21 and the third electrode 23, a force acts on the charged particles existing on the surface 20 a of the dielectric 20, and the induced flow F is generated. While being continuously generated, the induced flow F can be accelerated.

  In this way, the second electrode 22 and the third electrode 23 maintain the third electrode 23 at a predetermined potential in order to accelerate the induced flow F. The first electrode 21 and the third electrode 23 mainly accelerate the charged particles, that is, the induced flow F.

  As described above, according to the airflow generation device 10 of the embodiment, the electrodes (first electrode 21 and second electrode 22) for generating a dielectric barrier discharge and generating low-temperature plasma are generated. An electrode for accelerating charged particles in the low-temperature plasma, that is, accelerating the induced flow F can be configured separately.

  By providing an electrode for accelerating the induced flow F, charged particles existing on the surface 20a of the dielectric 20 can be obtained even after the discharge between the first electrode 21 and the second electrode 22 is self-extinguished. It can be accelerated. Therefore, the induced current F can be generated for a longer time in one cycle of the alternating voltage. Further, by controlling the voltage applied between the second electrode 22 and the third electrode 23, it is possible to control the electric field distribution and set the induced flow F to a predetermined flow velocity.

  Further, since the state of the plasma generated on the surface 20a of the dielectric 20 is determined by the specific capacitance of the capacitor composed of the first electrode 21, the second electrode 22, and the dielectric 20, the speed of the induced flow F that is desired to be generated. In some cases, the material of the dielectric 20 is limited. However, by providing the electrode that accelerates the induced flow F, the material of the dielectric 20 is not limited, and a material having a large dielectric constant can be used.

  In this way, by using a material having a large dielectric constant, even when the same voltage is applied between the first electrode 21 and the second electrode 22 as compared with the case where a material having a small dielectric constant is used. The voltage applied to the dielectric 20 decreases and the voltage applied to the discharge gap increases. Therefore, the density of charged particles can be increased, and a high-speed induced flow F can be generated. In other words, when the induced flow F having the same velocity is obtained, a material having a large dielectric constant is used, and thus, an application is made between the first electrode 21 and the second electrode 22 when a material having a small dielectric constant is used. It can be realized at a voltage lower than the voltage to be applied.

  Here, the airflow generation device 10 of the embodiment is not limited to the above-described configuration. FIG. 3 is a diagram schematically illustrating a cross section corresponding to the AA cross section of FIG. 1, showing another configuration of the airflow generation device 10 of the embodiment. In FIG. 3, the generated induced flow F is indicated by an arrow.

  As shown in FIG. 3, the surface of the third electrode 23 may be covered with a dielectric layer 50. The dielectric layer 50 is formed of the same material as that of the dielectric 20 described above. The dielectric layer 50 is composed of a thin film formed by, for example, chemical vapor deposition (CVD), sputtering, electrodeposition or the like.

  Thus, by covering the surface of the third electrode 23 with the dielectric layer 50, the third electrode 23 can be prevented from being directly exposed to plasma, and the third electrode 23 can be prevented from being worn. it can.

  According to the embodiment described above, it is possible to accelerate the flow velocity of the induced flow generated while suppressing the voltage applied to the pair of electrodes that cause the dielectric barrier discharge.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 10 ... Airflow generator, 20 ... Dielectric, 20a, 20b ... Surface, 21 ... 1st electrode, 22 ... 2nd electrode, 23 ... 3rd electrode, 30, 31, 32, 33, 34 ... Cable, 40 ... discharge power source, 41 ... acceleration power source, 50 ... dielectric layer, F ... induced flow.

Claims (5)

An airflow generator for generating an induced flow,
A dielectric made of solid,
A first electrode provided on the surface of the dielectric or embedded in the vicinity of the surface of the dielectric;
The dielectric is placed between the first electrode at a position farther from the surface of the dielectric than the first electrode and at a position shifted from the first electrode in the direction in which the induced flow flows. A second electrode provided via,
A third electrode provided at a position shifted from the second electrode in the direction in which the induced flow flows and on the surface of the dielectric, between the second electrode and the second electrode;
A first voltage application mechanism for applying an alternating voltage between the first electrode and the second electrode;
A second voltage application mechanism for applying a voltage between the second electrode and the third electrode;
The airflow generation device characterized in that the induced flow flows on the surface of the dielectric from the first electrode side toward the third electrode side.   The airflow generation device according to claim 1, wherein the voltage applied by the second voltage application mechanism is a DC voltage.   3. The airflow generation device according to claim 1, wherein a potential of the third electrode is lower than a potential of the first electrode.   The voltage applied between the second electrode and the third electrode is smaller than the voltage applied between the first electrode and the second electrode. The airflow generation device according to any one of 1 to 3.   The airflow generation device according to claim 1, further comprising a dielectric layer that covers a surface of the third electrode.

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