DE102006028614B4 - Method for operating a flow area element with plasma generation devices - Google Patents

Abstract

Method for operating a flow sheet element (1) with a plurality of plasma generating devices (2) distributed over the flow sheet element (1), which are designed as dielectrically disabled discharge devices and have electrodes (5, 6, 7, 8), a) electrical power pulses (12) b) first electrodes (6) of the plasma generating devices (2) are supplied with the power pulses (12), c) in the area of the first electrodes (6) of the plasma generating devices (2), which are supplied with the power pulses (12), a plasma is generated in a gaseous medium surrounding the first electrodes (6), characterized in that d) periodic signals (10a, 10b, 10c) are generated which are qualitatively different from the electrical power pulses, at least two periodic signals (10a , 10b, 10c, ...) have a phase shift, e) second electrodes (5a, 5b, 5c) which are in the vicinity of the first electrodes (6) and of the generated plasma are arranged, from which periodic signals (10a, 10b, 10c, ...) having a phase shift are applied, so that only forces are exerted on ionized particles of the generated plasma in the region of the second electrodes (5a, 5b, 5c) , f) by the action of the second electrodes (5a, 5b, 5c) with the periodic signals (10a, 10b, 10c) having a phase shift and the forces exerted on the ionized particles of the plasma, a conveying movement of the plasma along the flow surface element (1) is produced.

Description

TECHNICAL FIELD OF THE INVENTION

The invention relates to a method for operating a flow area element with a plurality of plasma generation devices distributed over the flow area element according to the preamble of claim 1.

STATE OF THE ART

• – eine Ventilation, insbesondere über perforierte Platten oder Rillen in der Oberfläche des Tragflügels,
• – eine aktive Grenzschichtabsaugung,
• – Konturbeulen in der Oberfläche des Tragflügels,
• – adaptive Oberflächen und/oder
• – mechanische Wirbelgeneratoren

zum Einsatz.In the case of a flight of an aircraft with high subsonic numbers, it may occur during the flow around the wings to form local supersonic areas on the top of the wing. This supersonic area is completed by a compression shock, particularly under off design flight conditions. When passing through the shock entropy of the flow medium increases while at the same time the resting pressure decreases. As a result, a so-called characteristic impedance is caused, which is typical for the Transsonikbereich. Furthermore, the interaction of the compression shock with the boundary layer on the wing can lead to a separation of the boundary layer, which leads to further losses. In addition, flow vibrations can occur. For known measures to influence such a compression shock and its effects come

• A ventilation, in particular via perforated plates or grooves in the surface of the wing,
• An active boundary layer suction,
• Contour bumps in the surface of the wing,
• - adaptive surfaces and / or
• - mechanical vortex generators

for use.

On the other hand, even in a low-flying phase during take-off and landing, an aircraft generates undesirable noise. To influence these noise sources during takeoff and landing, it is known to use mechanical vortex generators. In the case of motor vehicles, influencing of the flow conditions also takes place via mechanical elements and flow surface elements such as, for example, a spoiler.

For the aforementioned different types of vehicles, an attempt has been made in the recent past repeatedly to influence the flow conditions by using plasma generating devices.

• – zu einer Reduzierung einer Turbulenz im Bereich einer Grenzschicht und einer Reduzierung des Turbulenzgrads,
• – zu einer Unterdrückung einer Ausbildung von turbulenten Wirbeln und/oder
• – zur Abshwächung eines Stoßes im Bereich von Stirnseiten des Fahrzeugs

kommen. US Pat. No. 6,570,333 B1 discloses the incorporation of a pair of conductors under insulation of a flat or curved surface of a vehicle that is in the air, such as an aircraft, in the water, such as a ship, or on the ground, such as a motor vehicle or a utility vehicle, emotional. The pair of conductors are subjected to high-frequency energy such that a gaseous medium in the vicinity of the surface forms a plasma. The conductors in this case form electrodes which are spaced apart from one another and oriented parallel to one another. As a result of the formed plasma can lead to a reduction of the flow resistance of the vehicle. An arrangement of the conductors is also possible in small areas of an aircraft in order to change the flow resistance asymmetrically to the longitudinal axis of the vehicle, whereby a non-moving control surface is given. Furthermore, the conductors can be arranged in the region of an input, in the region of the interior or in the outlet region of a turbine, in order to achieve a change in the performance characteristic by influencing the flow. As a result of the formation of the plasma it can

• To reduce turbulence in the area of a boundary layer and to reduce the degree of turbulence,
• To suppress the formation of turbulent vortices and / or
• - To dampen a shock in the range of front sides of the vehicle

come.

If the generated plasma coincides between individual electrical pulses, a renewed ionization is required for a renewed plasma formation, which would make increased demands on the energy input and the formation of the electric fields. The electrical energy is provided at frequencies in the range of 1 MHz and 10 GHz. By the said frequency range can be achieved that a complete coincidence of the plasma between individual pulses of the oscillation is avoided.

The document proposes to arrange the conductors in a loop, so that a field is formed. Such a field is formed with parallel conductors in the form of sub-straight pieces, which are oriented transversely to the flow and coaxial with the flow. Another embodiment discloses conductors having a plurality of approximately circular, partially overlapping loops.

It is still out US Pat. No. 6,570,333 B1 It is known to sequentially excite a plurality of downstream electrodes to cause generation of peristaltic plasma waves over the surface of the aircraft. If these plasma waves run from the front to the rear, an acceleration of the plasma in the boundary layer is caused, whereby the flow u. U. can be made rather laminar and the formation of vertebrae is suppressed. In the event that the plasma waves run from back to front, this acts in the boundary layer against the aerodynamic flow, whereby u. U. the flow resistance of the aircraft is increased and a "braking effect" can be caused. Furthermore, by selectively driving the pairs of conductors, the Reynolds number for a transition to a turbulent flow can be raised locally or globally. In the operation of the conductors, the conductors in a pair are subjected to a phase shift of 180 ° with the high-frequency energy.

Out US Pat. No. 6,570,333 B1 It is also known to vary the distance of the conductors across the surface of the aircraft, whereby the density of the plasma can be varied according to local requirements. As an additional use for the formation of the plasma, the document also mentions that formation of ice in the area of a wing can be avoided and ice, which is already on a wing, can be removed. Another embodiment discloses parallel alignment of multiple sections of conductors for processing microelectronic circuits.

US 6 200 539 B1 describes as a side effect of electrodes of a plasma generating device that they exert on the ionized gaseous medium paraelectric electrohydrodynamic (EHD) forces. The document proposes to spatially distribute the electrodes over the flow area element in such a way that, due to the abovementioned forces, movements of the plasma and of the gaseous medium surrounding the plasma are produced, which influence the flow around the flow area element in a suitable manner. In this case, the electrodes are subjected to a single phase of a high-frequency excitation, whereby forces are generated, which are the result of an averaging of attractive and repulsive forces over a high-frequency cycle, which is also referred to as a second-order effect. Furthermore, it is mentioned in the document that much stronger effects should be possible when adjacent electrodes are excited with a multi-phase high-frequency excitation, whereby an electric field is to be generated, which is oriented parallel to the surface of the flow area element. Such an embodiment is also referred to as a "first-order EHD effect". The document is based on the basic idea that the forces exerted on the ionized gaseous medium are significantly determined by the orientation and the geometry of the electrodes and the relative arrangement of adjacent electrodes.

From the pamphlets US 5 414 324 A and US 5,387,842 A is also a generation of a plasma by excitation of electrodes, here known at a frequency between 5 KV and 100 KHz.

US Pat. No. 5,897,713 A relates to the formation of a plasma for the application of a film in a manufacturing process, for example for semiconductors.

Also US 5 797 563 A relates to a reduction in the density of a gas surrounding an aircraft in order to reduce the friction and the flow resistance. This is achieved by radiation of electromagnetic waves, which is to be carried out an ionization of the gas. Microwaves are emitted in the region of the front side of an aircraft and along a front contour of a tailplane or above and below a wing of an aircraft.

Also aimed at reducing the density of the gas flowing around the aircraft US 5 263 661 A from, in which case a laser is used to heat the gas.

Out US 4,917,335 A and US Pat. No. 3,620,484 It is known to produce in front of an aircraft a flame with which the gas flowing around the aircraft is to be heated in order to bring about a reduction in the density.

US 3 446 464 A discloses the arrangement of electrodes for generating different electrical potentials at the end edges of aircraft wings.

Further prior art is to influence flow and flow resistance including experimental results
E. Stanewsky, J. Fulker, J. Delery and J. Geissler: Drag Reduction by Passive Shock Control - Results of the EUROSHOCK Project, AER2-CT92-0049 supported by the European Union 1993-1995. Vol. 56 of Notes to Numerical Fluid Mechanics, Vieweg, 1997;
Stanewsky, E .; Delery, J .; Fulkner, J .; Matteis, P. de (Eds.): Drag Reduction by Shock and Boundary Layer Control - Results of the EUROSHOCK II Project; supported by the European Union 1996-1999, Springer Verlag, 2002
such as WO 02/081303 A1 . EP 1 373 067 B1 . US 3,095,163 A and DE 197 17 127 A1 refer to.

OBJECT OF THE INVENTION

• – der elektrischen Beaufschlagung der Plasmaerzeugungseinrichtungen,
• – des Energieaufwands und/oder
• – einer Wechselwirkung des Strömungsflächenelementes mit einem dieses umströmenden gasförmigen Medium

verbessert ist.The present invention has for its object to propose a method for operating a flow area element, which in terms

• The electrical charging of the plasma generating devices,
• - the energy expenditure and / or
• - An interaction of the flow area element with a this flowing around the gaseous medium

is improved.

SOLUTION

The object of the invention is achieved by a method having the features of independent claim 1. Further embodiments of the method according to the invention will become apparent according to the features of claims 2 to 5.

DESCRIPTION OF THE INVENTION

The present invention relates to flow area elements which serve to influence a flow of a gaseous medium in the surrounding area of the flow area element and / or to influence the forces exerted by the gaseous medium in the surrounding area of the flow area element on the flow area element. Such an influence is based on two effects, namely on the one hand a conversion of the gaseous medium into a plasma with ionized components, for which plasma generating devices are distributed over the flow area element, which are designed as dielectrically impeded discharge devices and having electrodes. On the other hand, forces can be exerted on the gaseous medium present in the plasma in ionized form by targeted generation of electric fields, which can ultimately result in an acceleration of the ionized particles and thus an influence on the flow around the flow surface element.

• a) Es hat sich gezeigt, dass eine Anregung von Elektroden mit elektrischen Leistungspulsen effizienter ist hinsichtlich einer Erzeugung eines Plasmas als eine Anregung der Elektroden mit moderat zeitveränderlichen Signalen wie beispielsweise mit einem sinusförmigen Signal. Dies hat zur Folge, dass für eine Beaufschlagung der Elektroden zur Erzeugung eines Plasmas mit elektrischen Leistungspulsen der zeitliche Abstand der Leistungspulse gegenüber einer Periodendauer eines harmonischen Signals u. U. vergrößert werden kann und/oder die Energie und Leistung der elektrischen Leistungspulse gegenüber der Energie und Leistung eines harmonischen periodischen Signals reduziert werden kann.
• b) Andererseits bedeuten impulsartige Beaufschlagungen der Elektroden stark zeitvariante elektrische Impulse zwischen benachbarten Elektroden, die damit stark veränderliche Kräfte auf ein erzeugtes Plasma ausüben können. Um eine gezielte Beschleunigung der ionisierten Teilchen des Plasmas zu erzeugen, ist somit eine impulsartige Anregung nicht zwingend erforderlich – u. U. kann sogar mit einem zwischen benachbarten Elektroden ausgebildeten elektrischen Feld mit konstantem Gradienten eine zumindest für ein zeitliches Teilinterval konstante Kraft vorteilhaft sein für eine Beschleunigung der geladenen Teilchen in eine gewünschte ”Förderrichtung”.

The invention is further based on the recognition that the requirements for an electrical application of electrodes in the region of the flow area element to bring about the two aforementioned effects are different:

• a) It has been found that excitation of electrodes with electric power pulses is more efficient in generating a plasma than excitation of the electrodes with moderately time varying signals, such as a sinusoidal signal. This has the consequence that for applying the electrodes for generating a plasma with electric power pulses, the time interval of the power pulses with respect to a period of a harmonic signal u. U. can be increased and / or the energy and power of the electric power pulses with respect to the energy and power of a harmonic periodic signal can be reduced.
• b) On the other hand, impulse-like exposures of the electrodes represent strongly time-variant electrical impulses between adjacent electrodes, which can thus exert highly variable forces on a generated plasma. In order to generate a targeted acceleration of the ionized particles of the plasma, thus a pulse-like excitation is not absolutely necessary - u. For example, even with a constant gradient electric field formed between adjacent electrodes, a force constant at least for a partial time interval can be advantageous for accelerating the charged particles in a desired "conveying direction".

The resulting conflict of objectives is for the US 6 200 539 B1 and US Pat. No. 6,570,333 B1 known method solved in that a high-frequency signal is selected, which is sufficiently dimensioned to bring about ionization. An influence of the applied forces on an electric field is brought about by arrangement, asymmetrical distances and orientation of the neighboring electrodes, s. US 6 200 539 B1 , Thus, an electrical signal is suitably adapted to both the generation of the plasma and the advantageous design of the electric field.

• – Einerseits werden elektrische Leistungspulse erzeugt, mit denen Elektroden der Plasmaerzeugungseinrichtungen beaufschlagt werden. Die Leistungspulse sind optimiert hinsichtlich einer Erzeugung eines Plasmas.
• – Daneben werden periodische Signale erzeugt, deren Energie und Leistung u. U. unter dem Niveau liegen kann, welches zur Erzeugung eines Plasmas erforderlich ist. Die periodischen Signale werden Elektroden zugeführt, die im Umgebungsbereich des erzeugten Plasmas angeordnet sind. Hierbei handelt es sich nicht um die Elektroden, die zur Erzeugung eines Plasmas dienen, sondern um zusätzliche Elektroden, die ausschließlich zur Ausübung von Kräften auf ionisierte Teilchen dienen. Durch Beaufschlagung dieser Elektroden wird eine Förderbewegung des Plasmas entlang dem Strömungsflächenelement erzeugt. Damit kann das periodische Signal gezielt auf eine Optimierung der Förderbewegung ausgelegt werden, ohne dass die Optimierung an die Erfordernisse für eine Erzeugung eines Plasmas angepasst werden muss.

According to the invention, two qualitatively different signals are used to produce the previously described desired effects a), b), which can each be optimized for one of the desired effects:

• On the one hand electrical power pulses are generated, which are applied to electrodes of the plasma generating devices. The power pulses are optimized for generation of a plasma.
• - In addition, periodic signals are generated whose energy and power u. U. may be below the level required to produce a plasma. The periodic signals are applied to electrodes disposed in the surrounding area of the generated plasma. These are not the electrodes used to generate a plasma, but additional electrodes that are used exclusively to apply forces to ionized particles. By applying these electrodes, a conveying movement of the plasma along the flow area element is generated. Thus, the periodic signal can be designed specifically for optimizing the conveying movement, without the optimization having to be adapted to the requirements for generating a plasma.

While according to US 6 200 539 B1 For periodic signals an electric field has been generated primarily by an asymmetrical arrangement of a plurality of electrodes of the same potential, the invention proposes that the periodic signals are supplied to the electrodes for generating a conveying movement with a phase shift. As a result of the phase shift, regardless of a position and / or orientation of the electrodes, an electric field may arise whose magnitude may depend on the amplitude of the periodic signal, the phase shift and the distance between the electrodes. Thus, in addition to influencing the resulting electric field on the arrangement and orientation according to US 6 200 539 B1 on the phase shift further influencing possibilities for the conveying movement due to the inventive design given.

The phase shift according to the invention can be actively generated by a suitable power supply, so that the power supply brings about a plurality of periodic signals with different, defined phase shifts. It is likewise conceivable that a central periodic signal generated by a power supply is purposefully provided with a phase shift by means of different electrical components, the components being interposed in a respective circuit having an electrode and the power supply. It is possible that both the periodic signal and the electrical power pulses are provided by the same electrical power supply. Alternatively, the periodic signals and the power pulses may be provided by separate power supplies.

A particularly simple embodiment of a periodic signal is given according to a development of the method according to the invention, if these are designed as harmonic signals (sinusoidal signals). For example, such signals may be provided and / or amplified by oscillators.

The electrodes can extend with the interposition of a dielectric straight or arbitrary curved or with partial line pieces in the region of a surface. According to a first embodiment, the electrodes, which are subjected to the power pulses, and the electrodes, which are acted upon by the periodic signals, at least in partial areas approximately perpendicular, namely at an angle between 80 ° and 100 °, oriented to each other. As a result, a plasma field extending in parallel with the electrodes subjected to the power pulses is acted upon by forces applied approximately in the direction of its longitudinal extent by the electrodes acted upon by the periodic signals.

In the event that an exertion of forces transverse to the longitudinal extension of such a plasma field is desired, this can be produced in a particularly simple manner by the electrodes acted upon by the power pulses and the electrodes acted upon by the periodic signals being oriented approximately parallel to one another at least in partial regions are, namely at an angle of -10 ° to + 10 °.

For example, by choosing a phase shift of the periodic signal from adjacent electrodes, the size of the electric field between the electrodes may be affected. On the other hand, there is a change in the electric field in accordance with the distance of the adjacent electrodes. A particularly homogeneous field in the region of the surface of a flow area element also over a plurality of adjacent, acted upon with periodic signals electrodes results when the electrodes are approximately equidistant from each other and the phase shifts between adjacent electrodes are each approximately constant.

Advantageous developments of the invention will become apparent from the claims, the description and the drawings. The advantages of features and of combinations of several features mentioned in the introduction to the description are merely exemplary and can come into effect alternatively or cumulatively, without the advantages having to be achieved by embodiments according to the invention. Further features are the drawings - in particular the illustrated geometries and the relative dimensions of several components to each other and their relative arrangement and operative connection - refer. The combination of features of different embodiments of the invention or of features of different claims is also possible deviating from the chosen relationships of the claims and is hereby stimulated. This also applies to those features which are shown in separate drawings or are mentioned in their description. These features can also be combined with features of different claims. Likewise, in the claims listed features for further embodiments of the invention can be omitted.

BRIEF DESCRIPTION OF THE FIGURES

In the following the invention will be further explained and described with reference to preferred embodiments shown in the figures.

1 shows a flow area element with plasma generating devices in a side view.

2 shows the flow area element according to 1 in a top view.

3 shows a further embodiment of a flow area element in a plan view.

4 shows a further embodiment of a flow area element in a plan view.

5 shows a schematic block diagram of a method according to the invention for operating a flow area element.

6 shows a schematic block diagram of a non-inventive method for operating a flow area element.

DESCRIPTION OF THE FIGURES

A illustrated in the figures flow area element 1 finds use, for example, in a vehicle which may be an aircraft, land vehicle, watercraft, spacecraft or as a vehicle for a combination of the aforementioned purposes. Alternatively, the flow area element 1 Use find in through-flow line systems, a medical management system, a pipeline, an exhaust pipe, a turbine, a conveyor for the treatment of a surface including a plasma cleaning, sterilization, a heating system, a ventilation system, an air conditioner u. ä. The flow area element 1 is used to influence a flow, avoiding or causing vortexes, creating a countercurrent flow, delayed or accelerated flow, or deliberately inducing or reducing flow-induced forces on the flow surface element. In the case of a use of the flow area element in a vehicle, the vehicle preferably moves in the range of low speeds from 50 km / h up to supersonic speeds in the transonic or supersonic range. Furthermore, the use of a flow surface element for an aircraft in any layers of air through to the use of a reentry aircraft (shuttle) is conceivable.

In the flow area element 1 are several plasma generating devices 2 through a dielectric 3 separated from each other. By means of the plasma generating device 2 can a the flow area element 1 in the region of the surface 4 flowing around the gaseous medium locally or along the extension of the plasma generating device 2 be converted into a plasma with ionized particles. For this purpose, all of the aforementioned plasma generating devices according to the prior art can be used. In particular, the plasma generating device generates a movement of the charged plasma particles, that is, ions or electrodes, which interact with the flow surface element. For example, the charged plasma particles can affect the neutral particles of the flow, so that their speed is changed, in particular the direction of the speed is changed, and / or the amount of speed is increased or decreased. Furthermore, it is possible that by the plasma generating device 2 the boundary layer is influenced, for example, the thickness of the boundary layer is changed. As explained above, via the plasma generating device 2 the flow in the area of the flow area element 1 accelerated or slowed down. Also a qualitative change of the flow in the area of the flow area element 1 is possible by deliberately generating a vortex or a turbulent flow is induced or the formation of vortices or a turbulent flow is selectively prevented. It has been shown that a use of a plasma generating device 2 in the region of a flow area element 1 is possible without the outer contour of the flow area element must be changed mandatory. As a result, the use of the plasma generating device 2 as an "add-on" possible without a re-interpretation of the flow area element is required. The plasma generating device 2 may be formed as a so-called "dielectrically impeded discharge device". Such discharge devices are also referred to in the literature as "dielectric barrier discharge". In the context of the present invention, the dielectrically impeded discharge device is understood to mean a device in which at least one dielectric, which forms a barrier, is interposed between two electrodes and the flow of the flow surface element. The dielectric may be a jacket of the electrode, which is integrated in the area of the surface of the same, for example in the flow area element.

For the in 1 and 2 illustrated embodiment of the flow area element 1 extend alternately from opposite end faces of the flow area element electrodes 5 in the area of the surface 4 , Transverse to these extend from a side surface of the flow area element 1 electrodes 6 located inside the flow area element 1 encased in the dielectric 3 , are arranged. Notwithstanding the simplified representation according to 1 can the electrodes 5 in the surface 4 be integrated with a smooth outer contour. The electrodes 5 . 6 are each aligned in a straight line, with the electrodes 5 (as well as electrodes 6 ) are each oriented parallel to each other and are arranged equidistant from each other.

For the in 3 illustrated embodiment are rectilinear electrodes 7 oriented parallel to each other and equidistant in the surface 4 the flow area element 1 integrated. Electrodes connected to the ground 8th are in the dielectric 3 integrated and parallel to each other and to the electrodes 7 oriented, the electrodes 8th off-center between adjacent electrodes 7 are arranged.

For the in 4 illustrated embodiment of a flow area element 1 owns these electrodes 5 , Electrodes 6 and grounded electrodes 8th , which are each arranged parallel to each other at equal distances from each other, wherein the electrodes 6 and 8th off-center between two adjacent electrodes 5 are arranged.

For the inventive method are in a power supply 9 periodic signals 10a . 10b . 10c , in particular harmonic signals, generated, s. 5 , The periodic signals 10a . 10b . 10c each have a phase shift, which may have the same or different amounts. In particular, the signals are um Signal 10a: S _10a = S _max sin (t), Signal 10b: S _10b = Smax sin (t + Δφ) Signal 10c: _10c S = Smax sin (t + 2Δφ)

The signals 10a . 10b . 10c be the electrodes 5a . 5b . 5c supplied, s. 1 and 2 respectively. 4 ,

Another power supply 11 generates electrical power pulses 12 with or without phase shift to the electrodes 6a . 6b . 6c be supplied, s. 1 and 2 respectively. 4 , Alternatively, the power supplies 9 and 11 be formed by a central power supply.

For the in 6 Non-inventive methods shown are the periodic signals 10a . 10b . 10c with the electrical power pulses 12 to the superimposed signals 13a . 13b . 13c superimposed. The superimposed signals 13a . 13b . 13c be the electrodes 7a . 7b . 7c supplied, s. 3 , According to 6 This results in a particularly compact embodiment of a method and the flow area element used in the process, since the same electrodes are used for application of power pulses to generate the plasma and an application of a periodic signal to generate the conveying movement. As a result, the number of electrodes can be reduced, in particular halved. This non-inventive embodiment means that the electrical power pulses and a periodic signal are superimposed to form a single signal, with which then the electrodes are acted upon. This has the consequence that the field due to the periodic signal acts directly in the area in which the plasma is generated, namely in the surrounding area of the same electrode.

In the event that, as in 3 and 4 shown connected to ground electrodes 8th are provided, a pulse operation for generating a plasma by alternately connecting the electrodes 8th and 6 be brought about.

As a rough guideline for a frequency of the power pulses about 100 kHz (± 10%, ± 20%) can be given, for which a coarse efficiency maximum can be detected experimentally.

LIST OF REFERENCE NUMBERS

1

Flow surface element

2

Plasma generating device

3

dielectric

4

surface

5

electrode

6

electrode

7

electrode

8th

electrode

9

power supply

10

periodic signal

11

power supply

12

electrical power pulses

13

superimposed signal

Claims (5)

Method for operating a flow area element ( 1 ) with several via the flow area element ( 1 ) distributed plasma generating devices ( 2 ), which are designed as dielectrically impeded discharge devices and electrodes ( 5 . 6 . 7 . 8th ), wherein a) electrical power pulses ( 12 ), b) first electrodes ( 6 ) of plasma generating devices ( 2 ) with the power pulses ( 12 ), c) in the region of the first electrodes ( 6 ) of plasma generating devices ( 2 ) with the power pulses ( 12 ), a plasma in one the first electrodes ( 6 ) surrounding gaseous medium, characterized in that d) periodic signals ( 10a . 10b . 10c ) are qualitatively different from the electric power pulses, wherein at least two periodic signals ( 10a . 10b . 10c , ...) have a phase shift, e) second electrodes ( 5a . 5b . 5c ) in the vicinity of the first electrodes ( 6 ) and the generated plasma are arranged by the phase-shifted periodic signals ( 10a . 10b . 10c , ...) are applied, whereby in the region of the second electrodes ( 5a . 5b . 5c ) only forces are exerted on ionized particles of the plasma generated, f) by the application of the second electrodes ( 5a . 5b . 5c ) with the phase-shifted periodic signals ( 10a . 10b . 10c ) and the forces exerted on the ionized particles of the plasma, a conveying movement of the plasma along the flow area element (FIG. 1 ) is produced. Method according to Claim 1, characterized in that the periodic signals ( 10a . 10b . 10c ) are formed as harmonic signals. Method according to claim 1 or 2, characterized in that with the power pulses ( 12 ) acted upon first electrodes ( 6a . 6b . 6c ) and with the periodic signals ( 10a . 10b . 10c ) acted upon second electrodes ( 5a . 5b . 5c ) are oriented approximately perpendicularly, namely at an angle of 80 ° to 100 °, to each other. Method according to claim 1 or 2, characterized in that with the power pulses ( 12 ) acted upon first electrodes ( 6a . 6b . 6c ) and with the periodic signals ( 10a . 10b . 10c ) acted upon second electrodes ( 5a . 5b . 5c ) are oriented approximately parallel, namely at an angle of -10 ° to + 10 °, to each other. Method according to one of the preceding claims, characterized in that adjacent to periodic signals ( 10a . 10b . 10c ) acted upon second electrodes ( 5a . 5b . 5c ) are approximately equidistant from each other and the phase shifts (Δφ 2Δφ, 3Δφ, ...) between adjacent second electrodes ( 5a . 5b . 5c ) are each approximately constant.

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