DE10050301A1 - Method to detach gaseous laminar border layer from high-speed material with gas molecules in border layer ionized and subjected to magnetic or electrical field - Google Patents

Abstract

The laminar border layer consists of gas molecules, some of which are ionized, the border layer is subjected to a field, which applies a force to the loaded particles contained in it. The field is a magnetic or electrical field. Ionization is by pref. short-wave electromagnetic radiation or particle jet, the loaded particles are accelerated in an electrical or magnetic field, ionized particles ionize neutral gas molecules by collision ionization.

Description

The invention relates to a method for detaching a gaseous laminar Boundary layer of high-speed material.

A gaseous substance adheres in particular to uniformly shaped material laminar boundary layer if the material is transported quickly. This The effect comes from the gas molecules surrounding the material force transmitted by friction. As a result, this is here to use the term high-speed material used broadly. It relates on evenly shaped continuous material as well as on individual workpieces that move quickly, for example in the production process become. However, it should be noted that smooth or at least relative continuous forms of material, which can include curvatures, usually favor the formation of a strong laminar boundary layer. However, such a laminar boundary layer is often undesirable because it is the Air circulation around the high-speed material is reduced.

As a result of this reduced air circulation, through air exchange favored physical and chemical processes such as evaporation or Evaporation of substances on the surface of the high-speed material, Temperature exchange between high-speed material and the environment or oxidation of substances on the surface is delayed. Also in mechanical consequences from the presence of the laminar Boundary layers are known. When winding material webs onto suitable ones The winding can reduce the friction between the layers of the Material web during the winding process between the material webs  cause that the material web is not wound up straight and none cylindrical film wrap is created.

To overcome all of these disadvantages, according to the current status the technology tries to comb-like or squeegee-like the laminar boundary layer Devices placed over the surface of the high-speed material to be fixed in place, or to replace the laminar one To transform flow into a turbulent flow.

There are limits to the success of these measures, however, because the aforementioned comb or squeegee-like devices in a certain Clearance must be placed over the high-speed material not to damage this. This distance leaves at least one thin laminar boundary layer on the high-speed material, which the the aforementioned physical and chemical processes are already clear impaired.

The object of the present invention is therefore the laminar boundary layer detach more completely from the high-speed material.

According to the invention, a method for detaching a gaseous laminar boundary layer from high-speed material is proposed, which is characterized by the following method steps:

• a) part of the gas molecules that make up the laminar boundary layer exists, is ionized;
• b) the gaseous laminar boundary layer is exposed to a field, which has a force effect on those in the gaseous laminar Boundary layer contains charged particles.

By the method according to the invention are within the laminar Boundary layer generates ions, which are also subsequently within the laminar Boundary layer are accelerated and in this way generate turbulence and the exchange of air between the surface of the high-speed Improve material and environment significantly.

Preferred embodiments of the invention take the acceleration of the ionized particles using a magnetic or an electrical Field in front. The ionization of some of the laminar molecules  Boundary layer can be done in several steps. So it is beneficial first carry out an initial ionization of gas molecules and this then ionized gas molecules in an electric field accelerate. In this way, collision ionization of other molecules takes place instead of. Impact ionization is an exponential process, so the number of ionized molecules increase rapidly, which is beneficial for the Turbulence generation is.

To the equipment complexity of a device for performing a To reduce such a procedure, it is advantageous if the field used for Acceleration of the molecules used to carry out the impact ionization is also used for turbulence generation.

However, for various reasons it may also be appropriate to use the Impact ionization and the further acceleration of the molecules of different fields or from a field with different To have directional components carried out. In this way it is possible the molecules in one direction of movement, at least those for impact ionization to convey necessary energy while the energy in another Direction of movement at will, for example for optimal Turbulence generation, can be adjusted.

If a direct bombardment of the surface of the high-speed material should be avoided by the molecules accelerated for impact ionization, the acceleration of the molecules used for impact ionization parallel to the Surface of the material take place during a second field of particles also mediates force components that are orthogonal to the surface of the material are directed.

It is also advantageous to have the movement of the particles parallel to the surface of the high-speed material through barrier walls at least once limit. These barrier walls can be connected to the electrodes that are used for the Generate acceleration electric field necessary for impact ionization, be identical. In this way, the accelerated gas molecules rebound the shock laws while maintaining a large part of their kinetic energy from these walls and carry out further impact ionizations. Around  To optimize the form of ionization can also be a periodic reversal of the Electrodes are charged.

In this way, a large number of ions are generated, which are predominantly and move orthogonal to the movement of the laminar boundary layer also contribute to the generation of turbulence. This type of ionization is can be used advantageously with or without initial ionization. Find one Initial ionization takes place, so a relatively large number of ions immediately trigger the Chain reaction ready. However, there are also in normal breathing air low concentration ions that trigger the ionizing chain reaction can.

If necessary, further acceleration of the particles by forces in in a direction orthogonal to the surface of the web, more Generate turbulence and the exchange of air between the Material surface and the environment to improve further.

It is advantageous to ionize or initial ionize a portion of the Molecules that make up the laminar boundary layer, UV rays, sufficiently short-wave laser steels, cathode steels, as well as X-ray or use γ-rays. Regarding the laser steels it should be mentioned that it is now possible to use relatively short-wave radiation, for example To provide excimer lasers. Furthermore, longer waves Laser sources such as laser diodes often devices that Generation of short-wave radiation, for example by photoluminescence make, downstream. Also the rays provided in this way are referred to in the context of this application with laser beams.

Another advantageous way of providing ions in the Laminar boundary layer consists in the injection of gas molecules that are lighter are to be ionized as the extremely stable oxygen and Nitrogen molecules, which are usually predominant in the ambient air. Advantageous methods for providing a magnetic field are in the Use of electromagnets, permanent magnets and a combination of both types of magnets. Especially the exclusive or complementary one The use of permanent magnets is advantageous in many applications, because by now suitable alloys, which are usually  Contain rare earth metals, allow significant field strengths to be reached without that electrical power has to be used.

The question of which temporal course the magnetic field should have to turbulence It has to be decided depending on the area of application. Therefore can Equal and alternating fields as well as overlaps of both field types are advantageous his. Alternating fields have the advantage over identical fields, thanks to the associated reversal of the force of the field to more disorder in of the laminar flow. The advantage of same fields is that lasting force effect, a longer acceleration phase in a Direction allowed.

Further features and advantages of the invention result from the others Subclaims and the description below in connection with the Drawings in which exemplary embodiments of the invention are schematic are illustrated. The figures show:

Fig. 1 is a sketched side view of a device in which the ionization of molecules of the laminar boundary layer with a radiation source and the force effect on the charged particles with a magnetic field is caused.

Fig. 2 is a sketched top view of a device in which the ionization of molecules of the laminar boundary layer with two electrodes and the force effect on the charged particles is caused by an electromagnet.

Fig. 3 shows a section through a conveyor belt, which is located in the air gap of an electromagnet.

Fig. 4 shows a section through a material web, which is located in the air gap of an electromagnet. The electromagnet is rotated through 90 ° with respect to the magnet shown in FIG. 3.

Fig. A sketched plan view of a device which ionizes molecules of a laminar boundary layer with radiation, and a specific mirror assembly 5.

Fig. 6 A sketched plan view of a device which molecules initialionisiert a laminar boundary layer with radiation, and then providing an electric field in a particular arrangement of electrodes which provides for the impact ionization and the generation of turbulence.

Fig. 1 shows a material web 1 , which is moved on rollers 2 in the transport direction at speed v. A laminar boundary layer 4 is located above the surface of the web 1 . Molecules of this laminar boundary layer are ionized by the radiation indicated by the arrow 15 of the radiation source S. The sketched electromagnet 3 generates a magnetic field B which exerts a force F, which points into the plane of the drawing, on the charged particles.

Fig. 2 shows a plan view of a conveyor belt 6 which workpieces 7 is moved in the transport direction. The workpieces pass between the electrodes 5 , which are charged with the voltages U and -U.

The electrodes can be reversed periodically if necessary. The direction of the acceleration of charged particles in the electric field is indicated by arrow 8 . The charged particles then get into the magnetic field which is provided by the electromagnet 3 with the windings 9 . The magnetic field exerts forces on the charged particles, which are represented by the arrow F. The arrow 10 outlines eddies or turbulences that arise.

Fig. 3 shows a section through a conveyor belt 6 , which leads workpieces, not shown at this point, through the air gap 14 of an electromagnet 3 with the windings 9 .

In FIG. 4 is a section through a web of material 1, which is guided through the air gap 14 of the electromagnet 3. The electromagnet is shown rotated by 90 ° relative to the material web 1 with respect to the position which the electromagnet 3 in FIG. 3 has with respect to the conveyor belt.

Fig. 5 shows a plan view of a web of material. The radiation source S emits a radiation which is reflected by the mirrors 11 in such a way that it crosses the width of the web several times and in this way ionizes as many molecules as possible or causes them to decay.

Laser beams are particularly suitable for devices of this type because of their Beam due to the special properties of laser light (Coherent length, monochrome, etc.) runs very little apart.

Fig. 6 again shows a plan view of a conveyor belt. Both the pointed electrodes 13 and the counter electrode 12 are shown above the conveyor belt. The radiation source S, which is held by the arm 16 above the material, in turn emits an ionizing radiation, which is indicated by the arrow 15 . In this exemplary embodiment, the radiation ensures initial ionization, which leads to an increase in the ion concentration in the region of the electrodes 13 . The impact ionization therefore starts with an increased number of charged particles which are accelerated in the direction of the counterelectrode 12 and at the same time ionize air molecules and cause vortices via the mechanism of the impact ionization.

With a view to the figures described and the method according to the invention the following should be emphasized at this point. The lifespan of charged particles is extremely low, at least under standard conditions. Hence the sequence of the method steps according to the invention often both spatially and temporally an immediate or - as the last embodiment shows - even simultaneously. In this case, the word process steps is used only for Differentiation of different physical processes, as a rule can also be caused by different measures.

The spatial differentiation that was made in FIGS. 1 and 2, for example, between the location of the ionization and the effect of the magnetic field has mainly illustrative reasons.

As a rule, both processes can take place in one place. Also different or differently aligned electrical or magnetic Fields can often overlap in one place without the ability to develop different or different effects to lose.  

LIST OF REFERENCE NUMBERS

1

web

2

roll

3

electromagnet

4

laminar boundary layer

5

electrodes

6

conveyor belt

7

workpiece

8th

arrow

9

windings

10

arrow

11

mirror

12

counter electrode

13

electrode

14

air gap

15

arrow
S radiation source
v The speed of the path or workpiece
B magnetic field
E electric field
U voltage
x, y, z coordinates

Claims (17)

1. Method for detaching a gaseous laminar boundary layer from high-speed material characterized by the following method steps:

• a) part of the gas molecules that make up the laminar boundary layer is ionized;
• b) the gaseous laminar boundary layer is exposed to a field which exerts a force on the charged particles contained in the gaseous laminar boundary layer.

2. The method according to claim 1, characterized in that the field, which acts on the force in the gaseous Boundary layer containing charged particles exerts a magnetic field is. 3. The method according to claim 1, characterized in that the field, which acts on the force in the gaseous Boundary layer contains charged particles, an electrical Field is.   4. The method according to one or more of the preceding claims, characterized in that the ionization takes place in the following two process steps:

• a) initial ionization of part of the gas molecules that make up the laminar boundary layer by means of a preferably short-wave electromagnetic radiation or a particle beam;
• b) acceleration of the resulting charged particles in an electric or magnetic field;
• c) Collision ionization of other previously neutral gas molecules by the already ionized and accelerated particles.

5. The method according to claim 4 characterized in that that of impact ionization and that of further acceleration to the already ionized parts underlying force of one and in the same field. 6. The method according to claim 4 characterized in that that of impact ionization and that of further acceleration to the already ionized parts underlying force effect of two different fields, which are preferably orthogonal stand on each other. 7. The method according to one or more of the preceding claims characterized in that the acceleration of the particles for impact ionization by a first one Field essentially parallel to the surface of the high-speed Material is done while the second field is the ionized particles accelerated orthogonal to the surface of the high-speed material.   8. The method according to claim 7 characterized in that the movement of the particles parallel to the surface of the high-speed Material at least once through barrier walls, of which the particles bounce off and move in the opposite direction, is interrupted. 9. The method according to one or more of the preceding claims, characterized in that one or more of the following types of radiation are used for the ionization or initial ionization of part of the gaseous molecules of the laminar boundary layer:

• a) UV radiation
• b) UV laser beams
• c) cathode steels
• d) ion beams
• e) X-rays or γ-rays

10. The method according to one or more of the preceding claims characterized in that the ionization of part of the gas molecules that make up the laminar Boundary layer exists, is facilitated by easily ionizable Gas molecules are introduced into the laminar boundary layer. 11. The method according to any one of claims 1 and 2 and 4 to 10, characterized in that the force effect of a magnetic field acts on the ionized gas molecules, which is generated at least by one of the following measures:

• a) by a permanent magnet,
• b) by an electromagnet,
• c) by an electromagnet, in the iron core or pole pieces of which permanent magnets are integrated.

12. The method according to any one of claims 1 and 2 and 4 to 11, characterized in that a current is applied to the windings of the electromagnets, the course of which is characterized by at least one of the following terms:

• a) a direct current,
• b) a direct current on which alternating current components are superimposed,
• c) an alternating current.

13. The method according to any one of claims 1 and 2 and 4 to 12 characterized in that to compress the magnetic flux near the surface of the high-speed material ferrite materials with high permeability (µ) can be used. 14. The method according to any one of claims 1 and 2 and 4 to 13 characterized in that the high-speed material through the air gap (d) otherwise closed magnet is running. 15. The method according to any one of claims 1 and 2 and 4 to 9 characterized in that the force of an electric force on the ionized gas molecules Field acts, which by at least two with opposite Charge applied electrodes is generated. 16. The method according to one or more of the preceding claims characterized in that the laminar boundary layer is dissolved to dry paint, Paint, glue or similar substances that are on the surface of the high-speed material or the high-speed material Form, improve or enable material.   17. The method according to one or more of the preceding claims characterized in that the laminar boundary layer is dissolved to the temperature of the high-speed material or the substances on it to change as quickly as possible through the improved gas exchange.