阅读说明：本技术 一种可用于减阻的阶梯状随行波等离子体激励器 (Stepped traveling wave-following plasma exciter capable of being used for drag reduction ) 是由 喻明浩 金元中 郑博睿 赵太飞 付钰伟 葛畅 张雯 于 2021-01-04 设计创作，主要内容包括：本发明公开的一种可用于减阻的阶梯状随行波等离子体激励器,包括有安装在机翼表面上且相互平行排布的第一级随行波发生器及第二级随行波发生器,第一级随行波发生器及第二级随行波发生器为材质为绝缘材料的三棱柱体,第一级随行波发生器及第二级随行波发生器的一侧壁面安装在机翼表面；第一级随行波发生器朝向气流方向的一侧壁面上设置有条状上电级；第二级随行波发生器的内部开有下电极安装槽,下电极安装槽内安装有平板型下电极,平板型下电极与条状上电级相平行；平板型下电极接地；条状上电级接直流脉冲高电压。该等离子体激励器能够提升流动控制效果,达到降低摩擦阻力的目标。(The invention discloses a stepped traveling wave following plasma exciter for drag reduction, which comprises a first-stage traveling wave generator and a second-stage traveling wave generator, wherein the first-stage traveling wave following generator and the second-stage traveling wave following generator are arranged on the surface of a wing and are arranged in parallel, the first-stage traveling wave following generator and the second-stage traveling wave following generator are triangular prisms made of insulating materials, and one side wall surfaces of the first-stage traveling wave following generator and the second-stage traveling wave following generator are arranged on the surface of the wing; a strip-shaped charging stage is arranged on one side wall surface of the first-stage traveling wave generator facing to the airflow direction; a lower electrode mounting groove is formed in the second-stage traveling wave generator, a flat-plate-type lower electrode is mounted in the lower electrode mounting groove, and the flat-plate-type lower electrode is parallel to the strip-shaped upper electrode; the flat-plate lower electrode is grounded; the strip-shaped charging stage is connected with a direct current pulse high voltage. The plasma exciter can improve the flow control effect and achieve the aim of reducing the frictional resistance.)

1. A step-shaped traveling wave following plasma exciter for drag reduction is characterized by comprising a first-stage traveling wave generator (4) and a second-stage traveling wave generator (5) which are arranged on the surface of a wing and are arranged in parallel, wherein the first-stage traveling wave generator (4) and the second-stage traveling wave generator (5) are triangular prisms made of insulating materials, and one side wall surfaces of the first-stage traveling wave generator (4) and the second-stage traveling wave generator (5) are arranged on the surface of the wing; a strip-shaped upper electrode (1) is arranged on one side wall surface of the first-stage traveling wave generator (4) facing to the airflow direction; a lower electrode mounting groove (3) is formed in the second-stage traveling wave generator (5), a flat-plate-type lower electrode (2) is mounted in the lower electrode mounting groove (3), and the flat-plate-type lower electrode (2) is parallel to the strip-shaped upper electrode (1); the flat-plate type lower electrode (2) is grounded; the strip-shaped upper electrode (1) is connected with a direct current pulse high voltage.

2. The stepped traveling wave plasma exciter for drag reduction according to claim 1, wherein the first-stage traveling wave generator (4) and the second-stage traveling wave generator (5) are triangular prisms made of polytetrafluoroethylene.

3. The stepped traveling wave plasma actuator for drag reduction according to claim 1, wherein said dc pulsed high voltage is 5kv to 10 kv.

4. The stepped traveling wave following plasma exciter for drag reduction according to claim 1, wherein the strip-shaped upper electrode (1) is made of copper electrode and has a thickness of 0.1mm to 2 mm.

5. A stepped traveling wave following plasma actuator for drag reduction according to claim 1, wherein the flat plate type lower electrode (2) is a copper electrode having a thickness of 0.1mm to 2 mm.

Technical Field

The invention belongs to the technical field of plasma equipment, and particularly relates to a stepped traveling wave-following plasma exciter for drag reduction.

Background

In the face of the increasingly severe energy crisis, improving the fuel economy of transportation vehicles has become a necessary choice for research and development design. The friction drag accounts for a large proportion of the total drag of the aircraft, for example, the turbulent friction drag on the surface of a hypersonic large aircraft accounts for more than 50% of the total drag when the hypersonic large aircraft is cruising. The research result shows that: reducing the aerodynamic drag coefficient is one of the important means for reducing fuel consumption.

The drag reduction technology is mainly divided into active drag reduction and passive drag reduction according to whether the drag reduction control mode needs additional energy input.

The currently common passive drag reduction methods mainly comprise: the method is characterized in that a solid blade type vortex generator is additionally arranged on a wing, a tiny drag reduction groove is arranged, a drag reduction method of a compliant wall, a traveling wave drag reduction method and the like are arranged. The traveling wave drag reduction is a bionic drag reduction technology which is researched in recent years at home and abroad, does not bring additional equipment or extra energy consumption to a control object, and has important effects on economic value and military value. The wave-corrugated shape along the surface of the traveling wave is utilized to generate secondary flow at the wave trough under a certain flow condition, namely, a row of parallel artificial vortexes are initiated by the flow, so that free incoming flow flows on the parallel artificial vortexes, the sliding friction is changed into rolling friction, and the aim of reducing drag is fulfilled. However, most passive drag reduction methods have special effective working conditions, and in a complex flow field, the action and effect brought by the passive flow control technology are limited.

The active resistance reduction technology comprises a micro-flow blowing and sucking method, a zero-mass jet method, plasma flow control and the like. The plasma flow control is to break down air to generate plasma by driving high voltage, and plays a role in disturbing a flow field by utilizing characteristics such as impact effect, temperature rise effect, physical property change and the like when the plasma is generated. The plasma drag reduction technology is derived from a plasma flow control technology, a stimulator is used for generating plasma, the plasma and neutral particles collide with each other under the action of an electric field force to form particle jet flow, the characteristics of a surrounding flow field are changed, the number of low-speed strips of a vortex coherent structure on the surface of an airfoil is reduced, and the laminar flow state of surface flow is delayed, so that the drag reduction effect is achieved.

However, in the plasma flow control, the excitation intensity and the service life of the plasma exciter are limited, and the effect of the drag reduction depends on the excitation effect of the exciter in certain cases.

The research finds that: in the plasma exciter, the electrode is combined with the stepped dielectric layer, so that the volume of the dielectric layer of the exciter is reduced, the space for generating plasma is increased, and the efficiency of the plasma exciter is improved. In addition, the stepped dielectric layer is degraded slowly along with the operation of the exciter, and the service life of the exciter can be prolonged.

Therefore, how to combine the active resistance reduction technology and the passive resistance reduction technology, how to improve the excitation strength of the exciter and how to further improve the resistance reduction efficiency by combining the characteristics of the active resistance reduction technology and the passive resistance reduction technology are becoming the latest development trend for improving the resistance reduction efficiency.

Disclosure of Invention

The invention aims to provide a stepped traveling wave-following plasma exciter for reducing drag, which can improve the flow control effect and achieve the aim of reducing frictional resistance.

The invention adopts the technical scheme that the stepped traveling wave following plasma exciter for reducing drag comprises a first-stage traveling wave generator and a second-stage traveling wave generator which are arranged on the surface of a wing and are arranged in parallel, wherein the first-stage traveling wave generator and the second-stage traveling wave generator are triangular prisms made of insulating materials, and one side wall surfaces of the first-stage traveling wave generator and the second-stage traveling wave generator are arranged on the surface of the wing; a strip-shaped charging stage is arranged on one side wall surface of the first-stage traveling wave generator facing to the airflow direction; a lower electrode mounting groove is formed in the second-stage traveling wave generator, a flat-plate-type lower electrode is mounted in the lower electrode mounting groove, and the flat-plate-type lower electrode is parallel to the strip-shaped upper electrode; the flat-plate lower electrode is grounded; the strip-shaped charging stage is connected with a direct current pulse high voltage.

The present invention is also characterized in that,

the first-stage traveling wave generator and the second-stage traveling wave generator are triangular prisms made of polytetrafluoroethylene.

The high voltage of the direct current pulse is 5kv-10 kv.

The strip upper electrode is made of copper electrode with thickness of 0.1-2 mm.

The flat plate type lower electrode is a copper electrode with the thickness of 0.1mm-2 mm.

The invention has the beneficial effects that:

(1) according to the plasma exciter, accelerated neutral particle flow and vortex in the groove are superposed in the same direction, so that the generation of the vortex is accelerated, the strength of the vortex is improved, the sliding friction on the surface of the wing is converted into rolling friction, and the resistance reduction effect is achieved;

(2) according to the plasma exciter, the temperature in the groove is sharply increased due to the heating effect of plasma discharge, so that gas in the groove expands towards the outside of the opening of the groove, the coupling effect of a main flow on the upper surface of the wing and a vortex in the groove is more obvious, and the resistance reduction effect is further improved. The advantages of active control and passive control are combined, the mixed drag reduction effect is achieved, and the aerodynamic efficiency of the wing is improved.

(3) The plasma exciter has the following wavy appearance, plays a role in passive drag reduction, and does not increase additional resistance; the stepped insulating medium layer is adopted, so that the space generated by the plasma is increased, and the effect of the exciter is improved in a multiplied way.

(4) The plasma exciter has small volume and is suitable for most aircrafts.

(5) The plasma exciter of the invention is composed of two stages of traveling wave generators, and the number of the traveling wave generators can be flexibly installed and connected in series according to the use requirement, thereby replacing the efficiency of the traditional damping device.

(6) The plasma exciter has the advantages of power supply triggering, quick response, lighter weight and longer service life than the traditional exciter. The device can be matched with a closed-loop control system, and an exciter is pertinently started to carry out active control drag reduction according to the flight state of the aircraft.

Drawings

FIG. 1 is a schematic structural diagram of a stepped traveling wave-following plasma exciter for drag reduction according to the present invention

FIG. 2 is a schematic side view of a stepped traveling wave plasma exciter useful for drag reduction in accordance with the present invention.

FIG. 3 is a schematic diagram of the installation position of the plasma exciter and the direction of the jet flow generated by the plasma exciter according to the present invention.

FIG. 4 is a view of the peripheral flow field profile of an airfoil without the device installed;

FIG. 5 is a flow field profile of a wing fitted with a stepped traveling wave plasma actuator of the present invention useful for drag reduction.

In the figure, 1, a strip upper electrode, 2, a flat plate type lower electrode, 3, a lower electrode mounting groove, 4, a first-stage traveling wave generator and 5, a second-stage traveling wave generator.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The invention relates to a stepped traveling wave following plasma exciter for drag reduction, which comprises a first-stage traveling wave following generator 4 and a second-stage traveling wave following generator 5 which are arranged on the surface of a wing and are arranged in parallel, wherein a gap is not formed between the first-stage traveling wave following generator 4 and the second-stage traveling wave following generator 5, and a V-shaped groove is formed between the first-stage traveling wave following generator 4 and the second-stage traveling wave following generator 5; the first-stage traveling wave generator 4 and the second-stage traveling wave generator 5 are triangular prisms made of insulating materials, and one side wall surfaces of the first-stage traveling wave generator 4 and the second-stage traveling wave generator 5 are arranged on the surface of the wing; a strip-shaped upper electrode 1 is arranged on one side wall surface of the first-stage traveling wave generator 4 facing to the airflow direction; a lower electrode mounting groove 3 is formed in the second-stage traveling wave generator 5, a flat plate type lower electrode 2 is mounted in the lower electrode mounting groove 3, and the flat plate type lower electrode 2 is parallel to the strip-shaped upper electrode 1; the flat-plate type lower electrode 2 is grounded; the strip-shaped upper electrode 1 applies high voltage with fast rising and slow declining, and the strip-shaped upper electrode 1 is connected with direct current pulse high voltage or millisecond pulse alternating current high voltage or nanosecond pulse high voltage. And the projection of the strip-shaped upper electrode 1 on the plane of the flat-plate lower electrode 2 and the flat-plate lower electrode 2 are arranged without gap.

The first-stage traveling wave generator 4 and the second-stage traveling wave generator 5 are triangular prisms made of polytetrafluoroethylene.

The high voltage of the direct current pulse is 5kv-10 kv.

The strip upper electrode 1 is a copper electrode with the thickness of 0.1mm-2 mm.

The flat plate type lower electrode 2 is a copper electrode, and the thickness is 0.1mm-2 mm.

The invention relates to a stepped traveling wave following plasma exciter for drag reduction, which combines the passive drag reduction of the traveling wave and the active control technology of a novel plasma exciter. The working phase of the device is divided into two parts, as shown in figures 3 and 5:

(1) when the plasma exciter does not work, airflow flows through the highest point of the first-stage traveling wave generator 4 and then is opposite to low-speed airflow in the V-shaped groove to generate high-speed airflow rotating clockwise. When the airflow rotates to the opening above the V-shaped groove, the vortex rotating at high speed and the main flow flowing over the V-shaped groove are in relative action, move along the trailing edge of the wing along the airflow direction, and generate the same aerodynamic process with the insulation surface of the next second-stage traveling wave generator 5, so that the main flow on the upper surface of the wing is prevented from generating relative friction with the low-speed boundary layer on the surface of the wing, and further the aerodynamic resistance is reduced.

(2) When the plasma exciter works, a fast-rising slow-decay type waveform is adopted, so that a strip-shaped upper electrode 1 and a flat plate type lower electrode 2 of the exciter generate plasma discharge, charged particles move from the upper electrode to the lower electrode at a high speed and continuously collide with neutral particles in a V-shaped groove to generate momentum exchange, static neutral particles obtain momentum, the neutral particles perform particle jet under the action of an electric field force, and the particle jet flows along the surface of a step-shaped medium to generate three beneficial effects:

firstly, accelerated neutral particle flow and vortex in a groove are superposed in the same direction, so that the generation of the vortex is accelerated, the strength of the vortex is improved, and the resistance reduction effect is obviously improved;

secondly, the temperature in the groove is sharply increased due to the heating effect of plasma discharge, so that the gas in the groove expands towards the outside of the opening of the groove, the relative action of the main flow of the upper surface of the wing and the vortex in the groove is more obvious, the flow separation point moves backwards, the flow separation is inhibited, the laminar flow state of the surface of the wing is kept as much as possible, and the resistance reduction effect is further improved.

Thirdly, the exciter dielectric layer is a step-shaped insulating dielectric layer, the volume of the dielectric layer can be reduced, and the dissipation power of the dielectric layer is reduced, so that the dissipation power of plasma is reduced, the volume of the plasma is increased, the excitation effect of the plasma is greatly increased, and the excitation effect of the plasma can be up to 8 times of the conventional excitation effect.

The device is arranged at the maximum wing thickness position of the upper surface of the wing along the wing span direction, a plurality of groups of stepped traveling wave plasma exciters which can be used for reducing drag can be continuously arranged without gaps, a plurality of traveling wave generators in the shape of triangular prisms are sequentially arranged to form the stepped traveling wave exciters, the insulating medium layer of each exciter is in a stepped shape, and the extending direction of a groove formed by the device is vertical to the airflow direction of the upper surface of the wing. The appearance of an insulating medium layer of the device is V-shaped following wavy, and the V-shaped following wavy profile medium is formed by combining two stages of step-shaped devices without gaps.

The height of the plasma exciter is 10 mm-40 mm.

The laying length of the multiple groups of plasma exciters is 50-100 mm.

The active novel efficient plasma exciter drag reduction and the passive traveling wave drag reduction are combined to achieve the purpose of efficient drag reduction (as shown in figure 5). Experiments show that when the insulating dielectric layer is in a step shape, when the exciter discharges, the step-shaped dielectric layer 2 is slower in degradation than that of a conventional exciter, so that the time for the exciter to break down the dielectric layer is delayed, and the service life of the exciter is prolonged. Wherein, fig. 4 and fig. 5 are effect comparison diagrams, and the comparison can clearly show that the flow separation point moves backwards by adopting the combination of the active and the passive, the flow separation is delayed, and the effect of larger drag reduction is achieved.