JP6993665B2 - Plasma actuator - Google Patents

Description

The present invention relates to a plasma actuator.

Conventionally, there is known a technique of arranging a plasma actuator in an intake passage of an internal combustion engine through which gas flows to accelerate or accelerate the flow of gas in the intake passage.

Japanese Unexamined Patent Publication No. 2012-180799

Here, in order to increase the combustion efficiency of the combustion chamber in the internal combustion engine, it is preferable that the air-fuel mixture appropriately diffuses into the combustion chamber.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a plasma actuator that appropriately diffuses a jet stream.

One aspect of the present invention controls a pair of electrodes, a dielectric arranged between the electrodes, a voltage applying device that applies a voltage to the electrodes, and a voltage application to the electrodes by the voltage applying device. A voltage control unit is provided, and the voltage control unit has a first state in which a voltage is applied to the electrode, and a voltage lower than the voltage applied to the electrode in the first state without applying a voltage to the electrode. The second state of applying the voltage to the electrode is repeated in a predetermined application cycle to control the application of the voltage to the electrode, and the first state is controlled in one application cycle. The shearing force applied to the airflow when the speed difference between the airflows is relatively large between the first application period that causes the induced flow and the airflow generated in the first application period after the first application period. The first non-application period in which the second state is controlled only for the time when the airflow is separated from each other and shear does not occur, and the second application period in which the first state is controlled for a time shorter than the first application period. It is a plasma actuator that repeats the second non-application period for controlling the second state.

Further, in the plasma actuator of one aspect of the present invention, the voltage control unit has the first application period, the first non-application period, the second application period, and the second application period in one application cycle. By repeating the non-application period, the third application period in which the control of the first state is performed for a time equal to or less than the second application period, and the third non-application period in which the control of the second state is performed, to the electrode. Controls the application of voltage.

Further, in the plasma actuator of one aspect of the present invention, when the Reynolds number of the airflow is low, the Reynolds number of the airflow is the period during which the first state is controlled and the period during which the second state is controlled. It repeats with a lower frequency compared to the higher case.

According to the present invention, it is possible to provide a plasma actuator that efficiently diffuses a jet flow.

It is a figure which shows the operating principle of a plasma actuator. It is a figure which shows an example of the shape of the nozzle which concerns on this embodiment. FIG. 2 is a cross-sectional view of the nozzle shown in FIG. 2 in the CC direction. It is a figure which shows an example of the plasma region of the nozzle which concerns on this embodiment. It is a figure which shows an example of the structure of the plasma actuator which concerns on this embodiment. It is a figure which shows the application cycle of the voltage which concerns on this embodiment. It is a flow chart which shows an example of the operation of the voltage application device which concerns on this embodiment. It is a figure which shows an example of the control result acquisition environment of the plasma actuator which concerns on this embodiment. It is a graph which shows the relationship between the flow velocity of the jet flow controlled by the plasma actuator of this embodiment, and the distance from a nozzle. It is an image of the jet of condition 1 according to this embodiment. It is an image of the jet of condition 2 according to this embodiment. It is an image of a jet of condition 3 according to this embodiment. It is an image of a jet of condition 4 according to this embodiment.

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

[Principle of plasma actuator]
First, the operating principle of the plasma actuator will be described with reference to the figure.
FIG. 1 is a diagram showing an operating principle of a plasma actuator.
The plasma actuator includes a pair of electrodes 11 (inner electrode 11-1 and outer electrode 11-2), a dielectric 12, and a voltage applying device 20. A dielectric 12 is arranged between the inner electrode 11-1 and the outer electrode 11-2. In other words, the dielectric 12 is arranged at a position sandwiched between the inner electrode 11-1 and the outer electrode 11-2.

Further, in the following description, the XYZ Cartesian coordinate system may be used when explaining the configuration of each part of the plasma actuator. In this XYZ Cartesian coordinate system, the Y-axis indicates the vertical direction of each part configuration, the X-axis indicates the horizontal direction of each part configuration, and the Z-axis indicates the depth direction of each part configuration. Further, in the following description, the positive direction of the Y-axis is described as upward or upward, the negative direction of the Y-axis is described as downward or downward, and the positive direction of the X-axis is described as right or right. It is described as a direction, and the negative direction of the X-axis is described as left or left direction.

A voltage is applied to the electrode 11 from the voltage applying device 20. The voltage application device 20 is a regulated power supply capable of setting, for example, the intensity of the applied voltage, the AC frequency, the voltage application time, the voltage application cycle, and the like. Here, by applying an AC high voltage to the electrode 11 by the voltage applying device 20, a dielectric barrier discharge (plasma) is generated between the inner electrode 11-1 and the outer electrode 11-2 (plasma shown in the figure). Region 200). The AC high voltage applied by the voltage application device 20 is an AC frequency of about 7 kHz, and a peak-to-peak voltage of 16 kV (voltage Vpp in the figure) of + 8 kV centered on 0 V and -8 kV is applied. do. In the plasma region 200, plasma causes ionization of a gas, and positive ions and negative ions are generated.

During one cycle of the AC high voltage applied by the voltage applying device 20, when the negative gradient of the voltage changes, electrons are emitted from the inner electrode 11-1 toward the outer electrode 11-2, and the outer electrode 11-2 Electrons are charged on the upper surface, that is, on the surface of the dielectric 12. Further, when the negative gradient of the voltage changes, the negative ions move to the outer electrode 11-2 in the same manner as the electrons. Further, in one cycle of the AC high voltage applied by the voltage applying device 20, when the positive gradient of the voltage changes, the electrons charged on the surface of the dielectric 12 when the negative gradient of the voltage changes are sent to the inner electrode 11-1. Moving. Further, when the positive gradient of the voltage changes, the positive ions move to the outer electrode 11-2 side. At the time of the above-mentioned negative gradient change of voltage and the positive gradient change of voltage, the momentum is transferred by the positive ions and the negative ions colliding with the neutral particles that are not ionized, and the body force (hereinafter referred to as the induced flow 250) is transferred. ) Occurs. This induced flow 250 causes a velocity change in the airflow existing around the dielectric 12.

The plasma actuator 1 of the present embodiment includes a jet outlet (hereinafter referred to as a nozzle 10) in which an electrode 11 is arranged, and a voltage applying device 20. The plasma actuator 1 controls the flow velocity of the jet as the voltage applying device 20 controls the voltage applied to the electrode 11, and efficiently diffuses the jet. Hereinafter, a specific configuration of the plasma actuator 1 will be described. First, the details of the nozzle 10 will be described, and then the details of the voltage applying device 20 will be described.

[About the nozzle]
Hereinafter, the configuration of the nozzle 10 will be described with reference to the drawings.
FIG. 2 is a diagram showing an example of the shape of the nozzle 10 according to the present embodiment. Specifically, FIG. 2A is a view showing the nozzle 10 from above. Further, FIG. 2B is a view showing the nozzle 10 from below. In the present embodiment, the nozzle 10 includes an inner electrode 11-1 and an outer electrode 11-2, and a dielectric 12. As shown in FIG. 2, in an example of the present embodiment, the dielectric 12 has a shape having a cylindrical portion and a brim portion extending toward the outer side of the circular diameter on the bottom surface of the cylindrical portion. The outer electrode 11-2 is arranged on the side surface of the cylindrical portion of the dielectric 12. Further, the inner electrode 11-1 is arranged in a circular shape on the bottom surface of the brim portion of the dielectric 12.

FIG. 3 is a cross-sectional view of the nozzle 10 shown in FIG. 2 in the CC direction. The cross section in the CC direction is a surface that passes through the center of the circle of the cylindrical portion of the dielectric 12 and has an axis parallel to the Y axis (center axis AX shown), and is a surface parallel to the XY plane.
As shown in FIG. 3, the dielectric 12 is arranged at a position sandwiched between the inner electrode 11-1 and the outer electrode 11-2. In one example of the present embodiment, the nozzle 10 is arranged on a horizontal plane with the brim portion as the bottom surface.

FIG. 4 is a diagram showing an example of the plasma region 200 of the nozzle 10 according to the present embodiment. A comparator (not shown) for supplying a jet is connected to the nozzle 10 on the bottom surface of the nozzle 10. The nozzle 10 ejects a jet flow supplied from the comparator (hereinafter referred to as jet flow 900) through the nozzle 10 in the vertical direction upward. Further, when the voltage applying device 20 applies a voltage to the electrode 11, the induced flow 250 is generated in the upper direction in the vertical direction (positive direction of the Y axis).

[About voltage application device]
Hereinafter, the configuration of the voltage applying device 20 will be described with reference to the drawings.
FIG. 5 is a diagram showing an example of the configuration of the plasma actuator 1 according to the present embodiment.
As shown in FIG. 5, the nozzle 10 (electrode 11) and the voltage applying device 20 are connected. The voltage application device 20 includes a power supply unit 21, an operation unit 22, a control unit 23, and a storage unit 25 as its functional units. The application period information 25-1 is stored in the storage unit 25. The application period information 25-1 is information indicating a period in which a voltage is applied to the electrode 11 (hereinafter, application period) and a period in which voltage application to the electrode 11 is stopped (hereinafter, non-application period). In one example of the present embodiment, the application period information 25-1 is information in which information indicating the application period and the non-application period is associated with environmental information indicating the characteristics of the jet flow 900, the diameter of the nozzle 10, and the like. ..

The power supply unit 21 applies an AC high voltage to the electrode 11 based on the control of the control unit 23. Environmental information is input to the operation unit 22 by the user of the plasma actuator 1 or the like. The control unit 23 realizes a functional unit that controls the power supply unit 21 by executing a program stored in the storage unit 25 by a processor such as a CPU (Central Processing Unit). The control unit 23 may be realized by hardware such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), or by cooperation between software and hardware. You may. The control unit 23 acquires environmental information from the operation unit 22. Based on the environmental information acquired from the operation unit 22, the control unit 23 reads the application period information 25-1 associated with the environmental information from the storage unit 25. The control unit 23 controls the power supply unit 21 based on the read application period information 25-1.

[About voltage application cycle]
Hereinafter, the details of the voltage applied to the electrode 11 by the power supply unit 21 based on the control of the control unit 23 will be described.
FIG. 6 is a diagram showing a voltage application cycle according to the present embodiment.
The vertical axis of FIG. 6 shows the voltage applied by the power supply unit 21, and the horizontal axis shows the time. The control unit 23 controls the power supply unit 21 and repeats the application period and the non-application period to generate the induced flow 250. In the following description, the cycle in which the power supply unit 21 repeats the application period and the non-application period in accordance with the control of the control unit 23 will be referred to as an application cycle. Further, the reciprocal of the application cycle is described as the application frequency.

In one example of the present embodiment, the application cycle indicated by the application period information 25-1 includes a first application period (the period Δt11 shown), a first non-application period (the period Δt12 shown), and a second application period (shown). The period Δt13), the second non-application period (shown period Δt14), the third application period (shown period Δt15), and the third non-application period (shown period Δt16) are included in the order described. The first application period, the second application period, and the third application period are periods in which the power supply unit 21 applies a voltage to the electrode 11 based on the control of the control unit 23. The first non-application period, the second non-application period, and the third non-application period are periods during which the power supply unit 21 stops applying the voltage to the electrode 11 under the control of the control unit 23.

Here, the length of the period in which the power supply unit 21 applies the voltage to the electrode 11 is different between the first application period, the second application period, and the third application period. Specifically, in the first application period, the second application period, and the third application period, the second application period and the third application period are shorter.
The third application period is a time equal to or less than the second application period.

The first non-application period is a period in which the application of the voltage to the electrode 11 is stopped only for a period in which shear does not occur in the jet 900 whose flow velocity is changed by the induced flow 250 generated in the first application period. The second non-application period is a period in which the application of the voltage to the electrode 11 is stopped only for a time during which shear does not occur in the jet 900 whose flow velocity is changed by the induced flow 250 generated in the second application period. The third non-application period is a period in which the application of the voltage to the electrode 11 is stopped only for a time during which shear does not occur in the jet 900 whose flow velocity is changed by the induced flow 250 generated in the third application period. Further, the second application period and the third application period are shorter than the first non-application period.

The power supply unit 21 applies a high AC voltage of a peak-to-peak voltage (voltage Vpp in the figure) centered on 0 V based on the control of the control unit 23. In one example of the present embodiment, the power supply unit 21 has a peak-to-to-peak AC frequency of 7 kHz, + 8 kV centered on 0 V, and -8 kV, for example, based on the control of the control unit 23. A peak voltage is applied to the electrode 11.

As described above, the period Δt11 to the period Δt16 are determined by the application period information 25-1. When the Reynolds number of the jet 900 is 2000, the application period is, for example, about 14 msec (that is, the applied frequency is approximately 70 Hz). When the Reynolds number of the jet 900 is 2000, the period Δt11 is a period of about 39% of the application cycle, the period Δt12 is a period of about 10% of the application cycle, and the period Δt13 is a period of about 13% of the application cycle. Δt14 is a period of about 6% of the application cycle, period Δt15 is a period of about 9% of the application cycle, and period Δt16 is a period of about 23% of the application cycle.
When the Reynolds number of the jet 900 is 5000, the application cycle is, for example, about 5 msec (that is, the applied frequency is a frequency of 200 Hz). When the Reynolds number of the jet 900 is 5000, the period Δt11 is a period of about 35% of the application cycle, the period Δt12 is a period of about 11% of the application cycle, and the period Δt13 is a period of about 9% of the application cycle. Δt14 is a period of about 14% of the application cycle, period Δt15 is a period of about 9% of the application cycle, and period Δt16 is a period of about 22% of the application cycle.

[Correlation between Reynolds number and application cycle]
Here, the flow velocity of the jet 900 increases as the Reynolds number increases. Along with this, as the Reynolds number increases, the application cycle controlled by the control unit 23 becomes shorter (frequency becomes higher). Further, when the Reynolds number increases, the ratio of the non-application period (in this example, the first non-application period, the second non-application period, and the third non-application period) in the application cycle controlled by the control unit 23 increases. become longer.

In the above description, the case where the AC frequency of the AC high voltage applied by the power supply unit 21 to the electrode 11 is 7 kHz has been described, but the present invention is not limited to this. The AC frequency of the AC high voltage supplied by the power supply unit 21 to the electrode 11 may be a value other than 7 kHz. Here, when the AC frequency is a high frequency, the movement of positive ions and negative ions actively occurs due to the above-mentioned configuration. That is, when the AC frequency is a high frequency, the induced flow 250 is likely to occur. Therefore, the AC frequency of the AC high voltage applied by the power supply unit 21 to the electrode 11 is preferably a high frequency.

[About the operation of the voltage application device]
Hereinafter, the details of the operation of the voltage applying device 20 will be described with reference to the drawings.
FIG. 7 is a flow chart showing an example of the operation of the voltage applying device 20 according to the present embodiment.
The control unit 23 acquires the environmental information input to the operation unit 22 (step S110). Based on the acquired environmental information, the control unit 23 reads out the application period information 25-1 associated with the environmental information from the storage unit 25 (step S120). The control unit 23 controls the operation of the power supply unit 21 based on the read application period information 25-1 (step S130). Specifically, the control unit 23 controls the operation of the power supply unit 21 based on the application period, the non-application period, and the application cycle indicated by the read application period information 25-1.

[About the application cycle start period]
In the above description, the case where the application cycle starts from the first application period has been described, but the present invention is not limited to this. As for the application cycle, if a part of the repetition of the first application period, the first non-application period, the second application period, the second non-application period, the third application period, and the third non-application period is set as one cycle, any of them can be applied. It may start from the period of. For example, the application cycle may be started from the first non-application period, the second application period, the second non-application period, or the third application period. It may be started from the third non-application period.

[Characteristics of application cycle]
Further, in the above description, the case where the application cycle includes the third application period and the third non-application period has been described, but the present invention is not limited to this. The application cycle may include at least two periods in which the power supply unit 21 applies a voltage to the electrode 11 and has different lengths. The application cycle may include, for example, a first application period and a second application period, and may include a first non-application period and a second non-application period accordingly. Further, the application cycle may include three or more application periods and a non-application period according to the number of application periods.

[Plasma actuator control results]
Hereinafter, the control result of the induced flow 250 (jet 900) controlled by the plasma actuator 1 will be described.
FIG. 8 is a diagram showing an example of a control result acquisition environment of the plasma actuator 1 according to the present embodiment.
As shown in FIG. 8, when confirming the jet flow 900 controlled by the plasma actuator 1 (nozzle 10 and voltage applying device 20), the measuring device 40, the image pickup device 41, the laser device 50, and the comparator (hereinafter referred to as the comparator). 90) and are used. In one example of the present embodiment, the jet 900 supplied from the comparator 90 includes a tracer. The tracer is, for example, seed particles having a diameter of about 1 micrometer (for example, ondina oil). The laser device 50 irradiates the jet light 900 ejected through the nozzle 10 with the laser beam. The image pickup device 41 takes an image of the jet stream 900 (tracer) irradiated with the laser beam by the laser device 50. The measuring device 40 measures the velocity of the jet 900 based on the image showing the jet 900 captured by the image pickup device 41.

FIG. 9 is a graph showing the relationship between the flow velocity of the jet flow 900 controlled by the plasma actuator 1 of the present embodiment and the distance from the nozzle 10. The horizontal axis of FIG. 9 shows the ratio between the distance (hereinafter, distance x) of the nozzle 10 from the ejection port (hereinafter, the upper portion of the nozzle 10) and the circular diameter (hereinafter, the diameter d) of the cylindrical portion of the dielectric 12. Specifically, the horizontal axis shows a value obtained by dividing the distance x by the diameter d (hereinafter, the diameter-distance ratio). In one example of this embodiment, the diameter d of the nozzle 10 is 10 mm. Therefore, the scale on the horizontal axis indicates from 5 mm to 40 mm from the ejection port of the nozzle 10. Further, the vertical axis of FIG. 9 shows the value obtained by dividing the distance x by the diameter d as 0.5, that is, the velocity of the jet 900 at a position 5 mm away from the ejection port of the nozzle 10 (hereinafter referred to as the reference velocity U0). The ratio with the velocity of the jet 900 at the position (hereinafter, jet velocity U) is shown. Specifically, the vertical axis shows a value obtained by dividing the jet velocity U by the reference velocity U0 (hereinafter, jet velocity ratio).

Further, FIG. 9 shows waveforms W1 to W4. The first waveform W1 is a waveform showing the relationship between the jet velocity ratio and the diameter distance ratio when the control unit 23 controls the power supply unit 21 (hereinafter, condition 1) by the above-mentioned application cycle. The second waveform W2 is a waveform showing the relationship between the jet velocity ratio and the caliber distance ratio when the voltage applying device 20 does not apply a voltage to the electrode 11 (hereinafter, condition 2). The third waveform W3 is a waveform showing the relationship between the jet velocity ratio and the caliber distance ratio when the voltage is continuously applied to the electrode 11 by the voltage applying device 20 (hereinafter, condition 3). The fourth waveform W4 has a cycle having the same length as the application cycle, and the voltage is applied to the electrode 11 only for a period of 50% of the cycle, and the voltage is not applied to the electrode 11 only for the other 50% period ( Hereinafter, it is a waveform showing the relationship between the jet velocity ratio of the condition 4) and the diameter distance ratio.

As shown in FIG. 9, the first waveform W1 shows a value in which the jet velocity ratio at a position where the distance from the nozzle 10 of the nozzle 10 is 40 mm (diameter distance ratio is “4”) is smaller than in other cases. In other words, when the induced flow 250 is generated by the application cycle (condition 1), the jet velocity U at a position far from the nozzle outlet of the nozzle 10 becomes the slowest. Further, the second waveform W2 shows a value in which the jet velocity ratio at a position where the distance from the nozzle 10 of the nozzle 10 is 40 mm is larger than in other cases. In other words, when no voltage is applied to the electrode 11 (condition 2), the jet velocity U at a position far from the nozzle outlet of the nozzle 10 becomes the fastest.

Further, in the third waveform W3 and the fourth waveform W4, the jet velocity ratio at the position where the distance from the ejection port of the nozzle 10 is 40 mm shows a value larger than the first waveform W1 and a value smaller than the second waveform W2. show. In other words, in the case of condition 3 or condition 4, the jet velocity U at a position far from the ejection port of the nozzle 10 is faster than when controlled by the application cycle and slower than when no voltage is applied.

FIG. 10 is an image of the jet flow 900 under condition 1 according to the present embodiment. Specifically, it is an image in which the image pickup device 41 takes an image of the jet stream 900 when the voltage application device 20 applies a voltage to the electrode 11 and stops in the application cycle. In this case, as shown in FIG. 10, a vortex is periodically generated in the jet 900. Further, the jet stream 900 is diffused at a position far from the nozzle port of the nozzle 10 (diameter distance ratio is “4”).

FIG. 11 is an image of the jet flow 900 of the condition 2 according to the present embodiment. Specifically, it is an image in which the image pickup device 41 images the jet stream 900 when the voltage application device 20 does not apply a voltage to the electrode 11. In this case, as shown in FIG. 11, vortices are periodically generated in the jet 900, but the jet 900 is diffused even at a position far from the nozzle 10 of the nozzle 10 (diameter distance ratio is “4”). do not have.

FIG. 12 is an image of the jet flow 900 of the condition 3 according to the present embodiment. Specifically, it is an image in which the image pickup device 41 takes an image of the jet stream 900 when the voltage application device 20 continues to apply a voltage to the electrode 11. In this case, the jet 900 shown in FIG. 12 is more diffuse than the jet 900 shown in FIG. 11, but the vortex is not generated as in the jet 900 shown in FIG. Therefore, the jet 900 is not diffused at a position farther from the jet outlet of the nozzle 10 (diameter distance ratio is “4”) than the jet 900 shown in FIG.

FIG. 13 is an image of the jet flow 900 of the condition 4 according to the present embodiment. Specifically, the voltage was applied to the electrode 11 only for a period of 50% of the cycle having the same length as the application cycle, and the voltage was not applied to the electrode 11 for a period of 50% of the cycle. At that time, it is an image that the image pickup apparatus 41 imaged the jet stream 900. In this case, the jet 900 shown in FIG. 13 is more diffuse than the jet 900 shown in FIG. 11, and a vortex is generated as in the jet 900 shown in FIG. However, the jet 900 is not diffused at a position farther from the jet outlet of the nozzle 10 (diameter distance ratio is “4”) than the jet 900 shown in FIG.

In addition, in an example of this embodiment, the control unit 23 is an example of a voltage control unit.
Further, in the example of the present embodiment, the first application period is an example of the application period. The first non-application period is an example of a limited non-application period. The second application period and the third application period are examples of the short application period. The second non-applied period and the third non-applied period are examples of the non-applied period.

Further, in an example of the present embodiment, the control unit 23 controls the first state in the first application period, the second application period, and the third application period. Further, the control unit 23 controls the second state in the first non-application period, the second non-application period, and the third non-application period. Here, in each application period, the voltage value of the voltage applied to the electrode 11 by the power supply unit 21 based on the control of the control unit 23 may be a different voltage value.

In one example of the present embodiment, there are a plurality of short application periods (in this example, a second application period and a third application period) in the application cycle, and a number of non-application periods corresponding to the number of application periods (in this example, the second application period and the third application period). The case where the second non-application period and the third non-application period) are included has been described, but the present invention is not limited to this. The application cycle may include at least one short application period (for example, a second application period). Further, the application cycle includes a number (in this case, one) of non-application periods (for example, a second non-application period) corresponding to the application cycle.

[Summary of embodiments]
As described above, the plasma actuator 1 includes a nozzle 10 and a voltage applying device 20. The voltage application device 20 applies and stops the voltage to the electrode 11 arranged in the nozzle 10 according to the application cycle to generate the induced flow 250.
Here, when the value of the jet velocity ratio is small (for example, the first waveform W1) at a position far from the ejection port of the nozzle 10, it means that the velocity of the jet flow 900 is slowed down. When the velocity of the jet 900 slows down, it indicates that the jet 900 is diffusing. In the plasma actuator 1 of the present embodiment, the jet flow 900 can be efficiently diffused by the voltage application device 20 generating the induced flow 250 according to the application cycle.

Further, the plasma actuator 1 of the present embodiment generates an induced jet 250 according to the application period, and the induced jet 250 generated by the first application period, the induced jet 250 generated by the second application period, and the third application. The induced flow 250 generated by the period causes a vortex in the jet 900, respectively. Further, this vortex is paired at a position far from the ejection port of the nozzle 10 (for example, a position where the diameter-distance ratio is "4"). As a result, in the plasma actuator 1 of the present embodiment, a larger vortex is generated by pairing the vortices with each other, and the jet flow 900 can be efficiently diffused.
For example, by using the plasma actuator 1 of the present embodiment as a mechanism for diffusing the air-fuel mixture into the combustion chamber of an internal combustion engine, the air-fuel mixture can be efficiently diffused into the combustion chamber.

When the jet 900 to be controlled by the plasma actuator 1 of the present embodiment is a jet 900 having a specific feature, the storage unit 25 stores the application period information 25-1 corresponding to the specific feature. May be configured. Further, in this case, the voltage applying device 20 does not have to include the operating unit 22.

Further, in the above description, the case where the dielectric 12 has a cylindrical portion and a brim portion extending toward the outer side of the circular diameter on the bottom surface of the cylindrical portion has been described, but the present invention is not limited to this. The plasma actuator 1 may have any shape as long as a voltage can be applied to the electrodes 11 sandwiching the dielectric 12 to generate an induced flow 250. The plasma actuator 1 may have, for example, a plate-like shape shown in FIG.

[About other examples of non-application period]
Further, in the above description, the non-application period has been described as a period in which the power supply unit 21 stops applying the voltage to the electrode 11 based on the control of the control unit 23, but the present invention is not limited to this. The non-application period may be, for example, a period in which the power supply unit 21 applies a voltage lower than the application period to the electrode 11 based on the control of the control unit 23. Here, the voltage applied by the power supply unit 21 during the non-application period is such a low voltage that plasma is not generated or plasma is not generated until the induced flow 250 is generated. The low voltage value applied by the power supply unit 21 during the non-application period is a voltage value based on the shape and material of the dielectric 12. Further, when the power supply unit 21 applies a voltage to the electrode 11 during the non-application period, the voltage value of the voltage may be a voltage value that matches in any non-application period, and is different for each non-application period. It may be a voltage value.

Each part of the voltage application device 20 in each of the above embodiments may be realized by dedicated hardware, or may be realized by a memory and a microprocessor.

Each part of the voltage application device 20 is composed of a memory and a CPU (central processing unit), and the function is executed by loading a program for realizing the function of each part of the voltage application device 20 into the memory and executing the program. It may be the one that realizes.

Further, a program for realizing the functions of each part included in the voltage applying device 20 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed to perform processing. You may go. The term "computer system" as used herein includes hardware such as an OS and peripheral devices.

Further, the "computer system" includes the homepage providing environment (or display environment) if the WWW system is used.
Further, the "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, or a CD-ROM, and a storage device such as a hard disk built in a computer system. Further, a "computer-readable recording medium" is a communication line for transmitting a program via a network such as the Internet or a communication line such as a telephone line, and dynamically holds the program for a short period of time. In that case, it also includes those that hold the program for a certain period of time, such as the volatile memory inside the computer system that is the server or client. Further, the above-mentioned program may be for realizing a part of the above-mentioned functions, and may be further realized by combining the above-mentioned functions with a program already recorded in the computer system.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment and may be appropriately modified without departing from the spirit of the present invention. can. The configurations described in each of the above-described embodiments may be combined.

1 ... Plasma actuator, 10 ... Nozzle, 11 ... Electrode, 11-1 ... Inner electrode, 11-2 ... Outer electrode, 12 ... Dielectric, 20 ... Voltage application device, 21 ... Power supply unit, 22 ... Operation unit, 23 ... control unit, 25 ... storage unit, 25-1 ... application period information, 40 ... measuring device, 41 ... imaging device, 50 ... laser device, 90 ... comparator, 200 ... plasma region, 250 ... induced flow, 900 ... jet flow

Claims (3)

With a pair of electrodes,
The dielectric placed between the electrodes and
A voltage application device that applies voltage to the electrodes, and
A voltage control unit that controls the application of voltage to the electrodes by the voltage application device, and
Equipped with
The voltage control unit
A predetermined application cycle is a first state in which a voltage is applied to the electrode and a second state in which a voltage is not applied to the electrode or a voltage lower than the voltage applied to the electrode in the first state is applied to the electrode. It repeatedly controls the application of voltage to the electrodes.
In one application cycle, the first application period in which the induced flow is generated by controlling the first state, and the air flow generated in the first application period after the first application period are combined with each other. The first non-application period in which the second state is controlled only for the time during which shearing, which is a state in which the airflows are separated from each other, is generated by the shearing force applied to the airflow when the velocity difference is relatively large, and the first application period. The second application period in which the first state is controlled and the second non-application period in which the second state is controlled are repeated for a time shorter than the period.
Plasma actuator. The voltage control unit
In one application cycle, in addition to the first application period, the first non-application period, the second application period, and the second non-application period, the first application period or less is the time. The application of the voltage to the electrode is controlled by repeating the third application period for controlling the first state and the third non-application period for controlling the second state.
The plasma actuator according to claim 1 . The period for controlling the first state and the period for controlling the second state are repeated at a lower frequency when the Reynolds number of the airflow is low and as compared with the case where the Reynolds number of the airflow is high. The plasma actuator according to any one of claims 1 and 2 .

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