JP2018004059A - Airflow control apparatus and airflow control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an airflow control apparatus capable of producing sufficient airflow control effects even in a situation where a boundary layer of an airflow flowing through a surface of an object can become thicker.SOLUTION: An airflow control apparatus 10 includes a layer thickness reduction mechanism 20 and an airflow generator 30. The layer thickness reduction mechanism reduces a thickness of a boundary layer of an airflow 15 flowing through a surface of an object 12. The airflow generator is disposed on the surface of the object. The layer thickness reduction mechanism is disposed at an upstream side in a flow direction of the airflow in comparison with a position at which the airflow generator is disposed on the object.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to an airflow control device and an airflow control method.

  It is important to reduce the vibration and noise of the fluid device and to improve the efficiency of the fluid device by controlling the flow of fluid along the inside and the surface of the fluid device. As an apparatus for controlling the flow of fluid, development of an airflow generator that generates a plasma-induced flow by converting a part of the fluid into plasma has been underway.

  In this airflow generator, when a high voltage is applied at a high frequency, plasma is generated on the airflow generator, and the momentum of ions present in this plasma is transferred to the surrounding neutral gas molecules, so that a plasma-induced current is generated. A thin laminar flow called is generated.

  By applying the plasma-induced flow to the boundary layer of the flow, the velocity distribution of the boundary layer can be changed or a disturbance can be given. In other words, the action of this plasma-induced flow can forcibly cause a transition from laminar flow to turbulent flow, generate eddy currents, or extinguish eddy currents. It is possible to improve the aerodynamic characteristics of the fluid device by controlling the flow of the fluid.

JP 2008-25434 A

  By the way, such an airflow generation device is installed near the leading edge of a wing (such as a two-dimensional symmetric wing) in a fluid device, thereby improving the stall of fluid flow (airflow) at the leading edge of the wing. Efficient airflow control can be performed.

  However, in the airfoil, there is an airfoil having a shape in which the airflow stalls in the vicinity of the trailing edge of the wing, unlike the stalling of the airflow in the vicinity of the leading edge of the wing described above. In the case of the latter airfoil, even if an airflow generator is installed near the trailing edge of the blade, the boundary layer develops at a position upstream of the installation position of the airflow generator and its thickness increases. There arises a problem that a sufficient airflow control effect cannot be obtained.

  Therefore, the problem to be solved by the present invention is to provide an airflow control device and an airflow control method capable of exerting a sufficient airflow control effect even in a situation where the boundary layer of the airflow flowing on the surface of the object can be thick. That is.

  The airflow control device of the embodiment includes a layer thickness reduction mechanism and an airflow generation device. The layer thickness reduction mechanism reduces the thickness of the boundary layer of the airflow flowing on the surface of the object. The airflow generation device is installed on the surface of the object, and the layer thickness reduction mechanism is provided at a position upstream of the installation position of the airflow generation device on the object in the flow direction of the airflow.

The perspective view which shows roughly the structure of the airflow control apparatus which concerns on 1st Embodiment. The figure which shows schematically the structure of the airflow generator with which the airflow control apparatus of FIG. 1 was equipped. AA sectional drawing which shows the structure of the layer thickness reduction mechanism with which the airflow control apparatus of FIG. 1 was equipped. The figure which shows the state of the airflow when the plasma induced flow is not generated in the wing | blade which installed the airflow generation apparatus near the front edge (in the case of plasma OFF). The figure which shows the state of the airflow when the plasma induced flow is generated in the wing | blade which installed the airflow generator near the front edge (in the case of plasma ON). The figure which shows schematically the airflow which moves the surface of the nacelle of a windmill. The figure which shows schematically the airflow which moves the surface of a motor vehicle. The figure which shows roughly the airflow which moves the surface of a helicopter. The figure which shows the model of the wing | blade which the airflow stalls near the trailing edge. The figure which shows roughly the airflow which acts on a diffuser model. The figure which shows the state of the airflow in case the plasma induced flow is not generated in the back step which installed the airflow generator in the corner | angular part. The figure which shows the state of the airflow at the time of generating a plasma induced flow in the back step which installed the airflow generation apparatus in the corner | angular part. The figure which shows the state of an airflow when a tripping wire is installed in the upstream of the back step in addition to the structure of FIG. 8B. The figure which shows the state of the airflow when not generating the plasma induction flow in the wing | blade which installed the airflow generation apparatus in the vicinity of the peeling point of an airflow. The figure which shows the state of the airflow at the time of generating a plasma induced flow in the wing | blade which installed the airflow generation apparatus in the vicinity of the peeling point of an airflow. The figure which shows the peeling inhibitory effect of the airflow in case the airflow generator is installed in the vicinity of the peeling point of an airflow, and the plasma induced flow is not generated. The figure which shows the peeling inhibitory effect of the airflow at the time of generating the plasma induced flow in the blade | wing installed in the airflow separation point vicinity. The figure which shows the structure when the layer thickness reduction mechanism is not provided in the wing | blade which installed the airflow generation apparatus in the vicinity of the peeling point of an airflow. FIG. 11B is a diagram showing the relationship between the moving section of the airflow flowing on the surface of the blade and the effect of suppressing separation by the plasma-induced flow in the configuration of FIG. 11A. The figure which shows the structure at the time of providing the layer thickness reduction mechanism in the wing | blade which installed the airflow generation apparatus in the vicinity of the peeling point of an airflow. FIG. 11C is a diagram showing the relationship between the moving section of the airflow flowing over the surface of the blade and the effect of suppressing the separation by the plasma-induced flow in the configuration of FIG. 11C. The figure which shows the velocity distribution of the boundary layer in the case of not providing the layer thickness reduction mechanism in the wing | blade which installed the airflow generation apparatus in the vicinity of the peeling point of an airflow. The figure which shows the velocity distribution of a boundary layer at the time of providing the layer thickness reduction | decrease mechanism in the wing | blade which installed the airflow generation apparatus in the vicinity of the peeling point of an airflow. The perspective view which shows roughly the structure of the airflow control apparatus which concerns on 2nd Embodiment. The perspective view which shows roughly the structure of the airflow control apparatus which concerns on 3rd Embodiment.

Hereinafter, embodiments will be described with reference to the drawings.
<First Embodiment>
As shown in FIGS. 1 to 3, the airflow control device 10 according to the present embodiment includes a layer thickness reduction mechanism (boundary layer thickness reduction portion) 20 and an airflow generation device 30. The layer thickness reduction mechanism 20 reduces the thickness of the boundary layer of the airflow 15 flowing on the surface of the wing (object) 12 as will be described in detail later. On the other hand, a plasma-induced flow is generated by converting a part of the air flow 15 into plasma, and this plasma-induced flow is applied to the boundary layer with a reduced thickness.

  As shown in FIG. 2, the airflow generation device 30 includes dielectrics 33 and 34, a pair of first and second electrodes 31 and 32 that are opposed to each other with the dielectric 33 interposed therebetween, and first and second electrodes 31. , 32, and a discharge power supply (power supply device) 35 that applies a voltage between the two. The first electrode 31 is provided on the surface of the dielectric 33. The second electrode 32 is embedded between the dielectric 33 and the dielectric 34.

  The discharge power source 35 is connected to the first and second electrodes 31 and 32 via the cable 36 and applies an alternating voltage (alternating voltage) between the first electrode 31 and the second electrode 32. To do. The discharge power source 35 applies, for example, a pulse modulation voltage between the first and second electrodes 31 and 32 that can increase or decrease the voltage value or can be periodically turned on and off (intermittently ON / OFF). It has a pulse modulation function.

  Here, when a high voltage is applied between the first and second electrodes 31 and 32 from the discharge power source 35 at a high frequency, a dielectric barrier discharge occurs between the electrodes, and the discharge is accompanied by the dielectric barrier discharge. Plasma is generated. The momentum of ions present in the discharge plasma is transferred to the surrounding neutral gas molecules to generate plasma-induced flow (thin laminar flow). The plasma-induced flow flows along the surface of the first dielectric 33 so as to go from the first electrode 31 side to the second electrode 32 side.

  By applying such plasma-induced flow to the boundary layer of the airflow, the velocity distribution of the boundary layer can be changed or disturbance can be given. That is, the action of the plasma-induced flow can forcibly cause a transition from laminar flow to turbulent flow, generate vortex flow, or eliminate vortex flow, and thereby flow on the surface of the blade 12. It is possible to improve the aerodynamic characteristics and the like by controlling the air flow 15.

  4A and 4B, an air flow generation device 70 similar to the air flow generation device 30 described above is provided in the vicinity of the leading edge of a blade (two-dimensional symmetric blade) 71 that has caused a leading edge stall. When the voltage is intermittently applied to the generator 70 by pulse modulation control, the stall of the air current 72 at the leading edge of the blade 71 is improved, and the air current control is more efficient than the method in which the voltage is continuously applied. Is possible. In particular, it has been found that when the frequency of pulse modulation is set near the dominant frequency of the flow velocity fluctuation detected in the wake of the blade, the effect of attracting a large-scale separated flow to the blade surface appears.

  Regarding the mechanism of the action of the plasma-induced flow by such intermittent voltage application, the flow is attached by the case where a two-dimensional transverse vortex is released from the vicinity of the leading edge of the blade 71 and the turbulent transition. It is said that there is a case. It has also been found that it is efficient to set the installation position of the airflow generator 70 (the installation position of the first and second electrodes) close to the separation point of the airflow with respect to the blade.

  However, in the airfoil, there is an airfoil having a shape in which the airflow stalls in the vicinity of the trailing edge of the blade, as shown in FIG. 6, unlike the stalling of the airflow in the vicinity of the leading edge of the blade described above. Further, in the present embodiment, as shown in FIGS. 5A to 5C, as various objects (fluid devices) subject to airflow control, in various fluid devices such as a windmill nacelle 74, an automobile 75, and a helicopter 76, It is assumed that separation at the corners on the rear side of the fluid device is controlled instead of the front edge, and the wake (downstream airflow) is rectified.

  Therefore, the inventors of the present application experimentally studied a method for controlling the flow behind the fluid device using a plurality of models. First, as shown in FIG. 6, in the blade 71 where the air current 72 is separated near the trailing edge, an attempt was made to suppress separation with an airflow generator installed near the separation point S where the flow separated near the trailing edge. However, a sufficient effect was not obtained. Next, as shown in FIG. 7, in the diffuser model 73, an attempt was made to promote pressure recovery by the airflow generation device 70 installed in the vicinity of the separation point S, but a sufficient effect could not be obtained.

  Furthermore, as shown in FIG. 8A, in the air reattachment promotion experiment in which the air flow generation device 70 is installed at the corner of the back step 77 of the fluid device, the reattachment is promoted as shown in FIG. 8B by the plasma induced flow. Although it was possible, when the tripping wire 78 or the like was installed upstream of the back step 77, it was found that the airflow control effect was reduced as shown in FIG. 8C.

  As a result of comprehensive consideration of these results, even if an airflow generator is installed near the trailing edge of a wing or the like, a boundary layer develops at a position upstream of the installation position of the airflow generator and the thickness of the boundary layer develops. When it became thick, the subject that sufficient airflow control effect was not acquired became clear.

  Therefore, the airflow control device 10 of the present embodiment includes the layer thickness reduction mechanism (boundary layer thickness reduction part) 20 described above, as shown in FIGS. The layer thickness reduction mechanism 20 is provided at a position on the blade 12 on the upstream side in the flow direction of the airflow 15 with respect to the installation position of the airflow generation device 30 installed on the surface of the blade (object) 12.

  The layer thickness reduction mechanism 20 has a slit (opening) 21 for guiding a part 15 a of the air flow 15 flowing on the surface of the blade 12 toward the inside 12 a of the blade 12. The slit 21 is a slit configured by providing a step 22 having a gap D in the surface portion of the blade 12.

  More specifically, as shown in FIG. 3, the layer thickness reduction mechanism 20 includes an upstream side reduction portion 23 that constitutes a portion on the upstream side in the flow direction of the airflow 15 in the layer thickness reduction mechanism 20 main body, A downstream reduction portion 24 that constitutes a downstream portion of the layer thickness reduction mechanism 20 main body in the flow direction of the air flow 15. The surface of the upstream reducing portion 23 is formed by smoothly extending the upstream surface 14 of the blade 12. On the other hand, the surface of the downstream reduced portion 24 is smoothly connected to the downstream surface 16 of the blade 12.

  The upstream side reduction part 23 and the downstream side reduction part 24 are in a positional relationship such that they wrap around each other, and the upstream side reduction part 23 is disposed more inside the blade 12 body than the downstream side reduction part 24. A gap D between the upstream side reduction portion 23 and the downstream side reduction portion 24 is configured to be several milli-order or several tens of milli-order.

  In the layer thickness reduction mechanism 20, the airflow 15 that has flowed through the surface 14 of the blade 12 is divided by the tip E of the downstream reduction portion 24 when passing through the slit 21, and a part of the airflow 15 is upstream. The remaining airflow 15 flows into the slit 21 from the rear end portion of the reduced portion 23, while the remaining airflow 15 becomes an external flow that flows on the surface of the downstream reduced portion 24 and the surface 16 of the blade 12 to form a new boundary layer. To do. At this time, the thickness of the boundary layer newly formed on the corner flow side is smaller than the thickness of the original boundary layer.

  The shape of the distal end portion E of the downstream side reduced portion 24 is desirably a thin plate shape, a wedge shape (sharp edge), or a curved surface having a curvature radius as small as possible. The airflow generation device 30 including the first and second electrodes 31 and 32 is disposed on the surface 16 of the blade 12 on the downstream side of the downstream side reduction portion 24.

The surface of the first electrode 31 is installed so as to be flush with the surface 16 of the wing 12. The first electrode 31 may be embedded so that the surface thereof is not exposed.
On the other hand, as shown in FIG. 3, the second electrode 32 is arranged with its installation position shifted to the downstream side in the flow direction of the airflow 15 from the installation position of the first electrode 31. The second electrode 32 is buried deeper from the surface 16 of the blade 12 than the first electrode 31.

  Here, FIG. 9A is a diagram schematically showing a fluid flow (air flow 15) in the vicinity of the rear edge of the blade 12 (or in the vicinity of the rear of the vehicle) when the air flow control device 10 is not operated. On the other hand, FIG. 9B is a diagram schematically showing the flow of fluid (airflow 15) in the vicinity of the rear edge of the blade 12 (or the vicinity of the rear of the vehicle) when the airflow control device 10 is operated.

As shown in FIGS. 9A and 9B, the second electrode 32 included in the airflow generation device 30 is installed in the vicinity of the separation point S ₀ of the airflow (external flow) 15 that flows on the surface 16 of the wing (object) 12. It is desirable. The frequency of the alternating voltage applied by the discharge power supply 35 or the pulse modulation frequency is a frequency close to the dominant frequency fs of the eddy current 17 intermittently discharged from the separation point S _{0 in the} state where no discharge is applied. It is preferable. Specifically, these frequencies are preferably controlled to ± 10% of the dominant frequency fs.

  This range is preferable because, within this range, the discharge phenomenon of the vortex 17 can be efficiently resonated with the energy of the discharge and the vortex 17 can be strengthened. The material of the dielectric 33 between the first and second electrodes 31 and 32 of the airflow generation device 30 is not particularly limited, and a known solid dielectric material is applied. Examples of the material of the dielectric 33 include an electrically insulating material such as an inorganic insulator such as aluminum oxide (alumina) and mica, and an organic insulator such as polyimide, glass epoxy, rubber, and glass. It is possible to select and use the most suitable dielectric material. The upstream side reduction part 23 and the downstream side reduction part 24 of the layer thickness reduction mechanism 20 may be formed integrally with the main body of the blade (object) 12, or the upstream side reduction part 23, the downstream side reduction part 24, and the blade After the 12 main bodies are individually formed, they may be integrated.

Next, the operation (airflow control method) of the airflow control device 10 of the present embodiment will be described.
As shown in FIG. 9A, the air flow 15 flows along the curvature of the surface of the blade 12 in the first stage, but the separation occurs at the separation point S ₀ . At the time of separation, a lateral vortex (vortex) 17 having an axis parallel to the surface of the blade 12 and perpendicular to the flow direction of the airflow 15 is generated. The boundary layer is in an unsteady state in which the separation state shown in FIG. 9A and the adhesion state shown in FIG. 9B are repeated, and the transverse vortex 17 moves in the flow direction of the air flow 15 during this repetition of separation and adhesion. Released intermittently. The position of the separation point S ₀ is determined by the surface shape of the wing (object) 12 and the velocity of the airflow 15 (mainstream velocity).

  Therefore, when the flow causes separation, the air flow control device 10 is operated. In this case, for example, an alternating voltage is applied between the first and second electrodes 31 and 32 of the airflow generation device 30 by the discharge power source 35, and plasma is generated on the surface of the blade 12. A plasma induced flow is generated by transmitting the force received by the ions in the plasma from the electric field to the gas. The plasma-induced flow is preferably generated so as to flow along the flow direction of the air flow 15, but the direction of the plasma-induced flow may be reversed particularly when it is desired to give a disturbance to the boundary layer. When plasma-induced flow occurs, the low-speed part of the boundary layer of the airflow is accelerated by the plasma-induced flow and has an effective effect on the velocity distribution.

  For example, when an alternating voltage is applied, plasma is intermittently generated according to the frequency of the alternating voltage, so that the plasma induced current is intermittently generated in accordance with the period of the alternating voltage. Further, when pulse modulation control is performed to intermittently control the application of voltage when applying the alternating voltage, the plasma induced flow is intermittently generated corresponding to the frequency of this pulse modulation control.

  As shown in FIGS. 9A and 9B, when the airflow generation device 30 is not operated, the state of the lateral vortex 17 in the vicinity of the trailing edge of the blade 12 is an unstable state as described above. On the other hand, as shown in FIGS. 10A and 10B, when the airflow generation device 30 is provided, for example, the frequency of the alternating voltage to be applied or the frequency fc of the pulse modulation, that is, the frequency of the plasma-induced flow generated intermittently. Is tuned to the dominant frequency fs of the vortex flow (lateral vortex) emitted from the vicinity of the trailing edge of the blade 12, the released horizontal vortex 17 resonates and energy is injected, and the horizontal vortex 17 is strengthened. When the lateral vortex 17 is strengthened, the flow near the surface of the blade 12 is attracted to the surface of the blade 12 by the action of the reduced pressure of the lateral vortex 17 or the exchange of momentum inside and outside the boundary layer by the lateral vortex 17.

  As a result, as shown in FIG. 10B, large-scale separation is suppressed, and the fluid flow (air flow 15) moves so as to adhere to the surface of the blade 12. Thereby, in the wing | blade 12, effects, such as a lift improving and resistance reducing, are acquired.

  Here, the frequency of the alternating voltage applied between the electrodes or the frequency fc of the pulse modulation is based on the dominant frequency fs corresponding to the eddy current (eddy current emission frequency) emitted when no voltage is applied. Is set. Even if the frequency fc is not completely equal to the dominant frequency fs, a sufficient airflow control effect can be obtained as long as the value is within a range of ± 10% with respect to the dominant frequency fs. When the dominant frequency fs of the eddy current is not equal to the frequency of the alternating voltage or the frequency fc of the pulse modulation, the dominant frequency fs converges to the frequency fc.

The dominant frequency fs of the eddy current can be measured in advance as a function of the wind speed and stored in a database, and the dominant frequency fs can be determined by determining only the mainstream speed during operation. For this reason, the frequency control of the alternating voltage can be easily performed. Further, as shown in FIG. 10B, the separation point of the air flow 15, by the effect of the airflow generating device 30, moves from the S _off in the Figure 10B to S _on, the distance ΔS from the S _off to S _on, It can be regarded as a delamination suppressing effect (plasma effect ΔS) by the plasma induced flow.

  Next, based on FIGS. 11A to 11D, the operation of the layer thickness reduction mechanism (boundary layer thickness reduction part) 20 installed on the upstream side of the airflow generation device 30 will be described.

  FIG. 11A and FIG. 11B show a run-up section (moving section of the airflow flowing over the surface of the wing) L, a plasma effect (a delamination suppressing effect due to plasma-induced flow) ΔS, when the layer thickness reduction mechanism 20 is not provided. This shows the relationship. As shown in FIGS. 11A and 11B, the longer the length of the run-up section L, the smaller the plasma effect ΔS. When L is longer than a certain threshold, the plasma effect can hardly be observed.

  On the other hand, FIG. 11C and FIG. 11D show the relationship between the run-up section L and the plasma effect ΔS when the layer thickness reducing mechanism 20 is provided. As shown in FIGS. 11C and 11D, when the layer thickness reduction mechanism 20 is provided, the plasma effect ΔS is hardly affected by the length of the run-up section L.

The reason for the results shown in FIGS. 11A to 11D will be further described based on FIGS. 12A and 12B. FIG. 12A shows the velocity distribution of the boundary layer from the above-described running section to the separation point when the layer thickness reduction mechanism 20 is not provided. Here, the horizontal axis v in FIG. 12A represents the flow velocity, and the velocity distribution in FIG. 12A indicates that the velocity of the surface of the object is decreased by friction. X ₀ , X ₁ , and X _{2 in} FIG. 12A indicate positions on the surface of the wing (object) 12. The velocity distribution is different between the position X ₀ and the position X ₁ . That is, at the position X ₀ , the fluid has started to flow on the surface of the blade 12 (the airflow has started to move), and the boundary layer is thin. While the airflow moves (runs up) from position X ₀ to position X _1, the thickness of the boundary layer increases, and further passes over the curvature surface near the trailing edge of the wing (object) 12 to at the time it reaches the position X ₂ which is installed, the boundary layer becomes very thick.

On the other hand, FIG. 12B shows the velocity distribution of the boundary layer from the above-described running section L to the separation point when the layer thickness reduction mechanism 20 is provided. At position X ₀ , fluid has just started to flow over the surface of the wing 12 and the boundary layer is thin. While the thickness of the boundary layer increases while the airflow moves from position X ₀ to position X _1, the thickness of the boundary layer decreases when the airflow passes through the layer thickness reducing mechanism 20.

Furthermore, blade passes over the curvature surface near the trailing edge of the (object) 12, although the thickness of the boundary layer before it reaches the position X ₂ which is installed in the airflow generating device 30 increases, the position X ₂ by the action of the installed flow generator 30, the thickness of the boundary layer at the position X ₂ is thinner in comparison with the state shown in FIG. 12A. The plasma effect can be expressed by applying acceleration or disturbance by the plasma-induced flow to the thinned boundary layer.

  As described above, according to the airflow control device 10 and the airflow control method of the present embodiment, even in a situation where the boundary layer of the airflow flowing behind the fluid equipment such as the wings is sufficiently developed, the airflow generation device Since the thickness of the boundary layer at the installation position of the airflow generation device 30 can be reduced by the action of the layer thickness reduction mechanism 20 installed upstream of the airflow 30, the airflow control effect by the plasma-induced flow (airflow separation suppression effect) is sufficient. Can be demonstrated.

<Second Embodiment>
Next, a second embodiment will be described with reference to FIG. As shown in FIG. 13, the airflow control device 80 of this embodiment includes a layer thickness reduction mechanism 90 instead of the layer thickness reduction mechanism 20 provided in the airflow control device 10 of the first embodiment. The layer thickness reducing mechanism 90 has a gap (opening) 91 instead of the slit (opening) 21 of the layer thickness reducing mechanism 20.

The air gap 91 is provided so as to cross the surface of the wing (object) 92 with respect to the flow direction of the air flow 15. The air gap 91 functions as an opening for guiding (sucking) a part of the airflow (boundary layer) 95 flowing on the surface of the blade 92 toward the inside 92 a of the blade 92.

  Therefore, also in the airflow control device 80 of the second embodiment, since the thickness of the boundary layer can be reduced by the layer thickness reduction mechanism 90 installed on the upstream side of the airflow generation device 30, the downstream airflow generation device 30 generates the airflow. A sufficient airflow control effect can be obtained by the action of the plasma induced flow.

<Third Embodiment>
Next, a third embodiment will be described with reference to FIG. As shown in FIG. 14, the airflow control device 100 of this embodiment includes a layer thickness reduction mechanism 110 instead of the layer thickness reduction mechanism 20 included in the airflow control device 10 of the first embodiment. The layer thickness reducing mechanism 110 has a porous surface 111 instead of the slit (opening) 21 of the layer thickness reducing mechanism 20.

  The porous surface 111 is provided so as to cover a predetermined area on the surface of the wing (object) 112. The plurality of holes of the porous surface 111 are arranged along the flow direction of the air flow 115. The porous surface 111 functions as an opening for guiding (sucking) a part of the airflow (boundary layer) 115 flowing on the surface of the blade 112 toward the inside 112 a of the blade 112.

  Therefore, also in the airflow control device 100 of the second embodiment, since the thickness of the boundary layer can be reduced by the layer thickness reduction mechanism 110 installed on the upstream side of the airflow generation device 30, the downstream airflow generation device 30 generates the airflow. A sufficient airflow control effect can be obtained by the action of the plasma induced flow.

  According to at least one embodiment described above, a sufficient airflow control effect can be exhibited even in a situation where the boundary layer of the airflow flowing on the surface of the object can be thick.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit 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.

  10, 80, 100 ... Airflow control device, 12, 92, 112 ... Wing (object), 12a, 92a, 112a ... Inside of the wing, 14, 16 ... Surface of the wing, 15, 95, 115 ... Airflow, 17 ... Eddy current (Horizontal vortex), 20, 90, 110 ... layer thickness reduction mechanism, 21 ... slit (opening), 22 ... step, 23 ... upstream reduction part, 24 ... downstream reduction part, 30 ... air flow generator, 31 ... first DESCRIPTION OF SYMBOLS 1 electrode 32 ... 2nd electrode, 33, 34 ... Dielectric material, 35 ... Power supply for discharge, 91 ... Air gap (opening), 111 ... Porous surface, E ... Tip part of downstream reduction part.

Claims (8)

A layer thickness reduction mechanism that reduces the thickness of the boundary layer of the airflow flowing through the surface of the object;
An airflow generator installed on the surface of the object,
The layer thickness reduction mechanism is an airflow control device provided at a position upstream of the airflow generation device on the object in the flow direction of the airflow. The airflow control device according to claim 1, wherein the airflow generation device generates a plasma induced flow obtained by converting a part of the airflow into plasma and acts on the boundary layer having the reduced thickness. The airflow control device according to claim 1, wherein the layer thickness reduction mechanism has an opening for guiding a part of the airflow flowing on the surface of the object to the inside of the object. The air flow control device according to claim 3, wherein the opening is configured by providing a step with a gap in a surface portion of the object. The airflow control device according to claim 3, wherein the opening is provided so as to cross the surface of the object with respect to a flow direction of the airflow. The opening is provided on the surface of the object.
The airflow control device according to claim 3. The airflow control device according to any one of claims 1 to 6, wherein the object is a wing or a moving body. Reducing the thickness of the boundary layer of the airflow flowing over the surface of the object;
And a step of generating a plasma-induced flow in which a part of the airflow is converted into plasma and acting on the boundary layer with the reduced thickness.

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