CN106394941B - A method for derotation of space non-magnetized metal fragments - Google Patents

Abstract

The present invention relates to the methods that a kind of pair of space unmagnetized metal fragment carries out racemization to accelerate fragment cutting magnetic line using the speed of related movement between rotating excitation field and fragment, generates vortex torque, improves the function and effect of vortex torque, shortens the fragment racemization time.The method of the present invention is compared with research compared to the rotating excitation field opposite with the fragment direction of motion having the advantage that through foundation, increase the relative velocity moved between rotating excitation field and fragment, increase the vortex of fragment cutting magnetic line generation, to enhance racemization torque, the time of racemization is reduced.

Description

A method for derotation of space non-magnetized metal fragments

technical field

The invention belongs to the rotating magnetic field technology for derotating non-magnetized metal fragments in space, and relates to a method for derotating non-magnetized metal fragments in space. The invention relates to a derotation magnetic field setting method which utilizes the relative motion between a rotating magnetic field and a conductor to accelerate the conductor to cut the magnetic force line and form a derotation torque, and belongs to the technical field of space debris cleaning.

Background technique

"Space debris" means non-functional man-made objects in Earth orbit or re-entering the atmosphere, including fragments and components thereof. With the increasing frequency of human spaceflight activities, the number of space debris is increasing exponentially, and they are concentrated in areas with an altitude of 800-1000km. Due to the influence of space perturbation, these debris are often in a state of high-speed spin motion. This has brought great difficulties to the capture and clean-up of space debris. Derotation of space debris is a top priority for capture and cleanup. At present, there are mainly contact racemization and non-contact racemization. The magnetic field-based eddy current derotation technology for space debris is a non-contact derotation method. This research is still in its infancy, and the existing research mainly focuses on the derotation method under a constant magnetic field.

In the article "Study on the eddycurrent damping of the spin dynamics of space debris from the Ariane launcherupper stages" published in "ACTA ASTRONAUTICA" 2012, Volume 76, pages 145-153 (author Praly, N., etc.), discussed the The eddy current effect of the space debris produced by the upper stage of the Yana rocket under the action of the earth's magnetic field leads to the conclusion that the space debris will gradually stop spinning under the action of the earth's magnetic field. It has been theoretically shown that the constant magnetic field will dampen the rotational motion of space debris. This passive racemization takes a long time, usually about half a year.

In the article "Eddy currents applied to de-tumbling of space debris: Analysis and validation of approximate proposed methods" (authors Gomez, Natalia Ortiz, etc.) published in "ACTA ASTRONAUTICA", Volume 114, pages 34-53, 2015, it is proposed to establish a constant Magnetic field, active derotation technology using eddy current torque. In this method, the derotation of space debris is achieved by actively constructing a directional magnetic field, and the magnitude of the eddy current torque and the derotation time are studied. This technology only relies on a single set of coils to establish a constant magnetic field, and relies on the movement of fragments to cut the magnetic field lines to generate eddy currents and generate derotation torque. However, due to the low speed of debris movement, the size of the eddy current is limited, and the derotation torque is small.

The national invention patent "A Method and Device for Removing Space Debris" applied in 2013, patent application publication number CN103434658A, inventor: Li Yiyong, etc., proposed to change the movement of space debris through the combination of electric field force, magnetic field force or electromagnetic field force Speed and direction of motion, a method of removing space debris that deviates debris from a fixed orbit. This technique does not address the rotational motion and racemization of the fragments.

The prior art analyzes the generation mechanism and implementation method of eddy current torque. The magnetic field used is a constant magnetic field, and only depends on the eddy current torque generated by the rotational motion of the debris itself. The rotational speed of space debris is relatively slow, generally less than 60deg/s , the magnitude of the derotation torque is small, and the derotation time is longer.

Contents of the invention

technical problem to be solved

In order to avoid the deficiencies of the prior art, the present invention proposes a method for derotating non-magnetized metal fragments in space, using the relative motion speed between the rotating magnetic field and the fragments to accelerate the fragments to cut the magnetic field lines, generate eddy current torque, and improve The effect of the eddy current torque shortens the spin-off time of the fragments.

Technical solutions

A method for derotating non-magnetized metal fragments in space, characterized in that: a rotating magnetic field is applied around the non-magnetized metal fragments in space, the main axis of the rotating motion of the rotating magnetic field coincides with the main axis of the rotating motion of the fragments, and the direction of rotation of the rotating magnetic field The direction of rotation of the fragments is opposite; the magnetic field strength amplitude of the rotating magnetic field is constant.

The rotating magnetic field adopts a mechanical power device to drive the magnetic field generating device to rotate, and the mechanical power device drives the N magnetic pole and the S magnetic pole to rotate, the main axis of the movement coincides with the main axis of the rotational movement of the fragments, and the direction of the rotational movement of the magnetic field coincides with the direction of the rotational movement of the fragments. on the contrary.

The magnetic field generating device is an N magnetic pole and an S magnetic pole oppositely arranged to generate a single magnetic field or a combined magnetic field.

The rotating magnetic field is generated by a current-controlled magnetic field generating device.

The magnetic field generating device of the current control mode is composed of a plurality of coils, wherein each coil diameter passes through the fragment rotation axis, and every two adjacent coils form an included angle in space, and the included angle between different adjacent coils can be Different from each other, alternating current is passed into each coil to generate an alternating magnetic field, and the alternating magnetic field vectors generated by all coils are synthesized into a circular rotating magnetic field with a constant amplitude.

Beneficial effect

A method for derotation of non-magnetized metal fragments in space proposed by the present invention uses the relative motion speed between the external rotating magnetic field and the non-magnetized metal fragments to accelerate the fragments to cut the magnetic field lines, generate eddy currents in the metal fragments, and form eddy current torque derotation magnetic field. Compared with the existing research, the method of the present invention has the following advantages: by establishing a rotating magnetic field opposite to the moving direction of the fragments, the relative speed of the movement between the rotating magnetic field and the fragments is increased, and the eddy current generated by the fragments cutting magnetic force lines is increased, thereby enhancing The derotation torque is reduced, and the derotation time is reduced.

Description of drawings

Figure 1: Schematic diagram of space debris movement profile

Figure 2: Representation of a rotating magnetic field for derotation

(a) Representation in space (b) Representation in time

Figure 3: Schematic diagram of using a mechanical power device to drive a magnetic field generator to perform rotational motion

Figure 4: Schematic diagram of a magnetic field generator using two-phase alternating current

(a) Three-dimensional view; (b) Sectional view

Figure 5: Schematic diagram of the current and synthetic magnetic field at each moment of the magnetic field generator

(a) ω ₁ t = 0 (b) (c)ω ₁ t=π (d)

Detailed ways

Now in conjunction with embodiment, accompanying drawing, the present invention will be further described:

The present invention is a derotation magnetic field technology that utilizes the relative motion speed between an externally applied rotating magnetic field and non-magnetized metal fragments to accelerate the fragments to cut the magnetic lines of force, generate eddy currents in the metal fragments, and form eddy current torque. Its technical feature is that it contains the following content:

(1) The basic principle of derotation of rotating magnetic field

According to Faraday's law of electromagnetic induction, when a moving conductor cuts the magnetic force line, an induced electromotive force will be formed inside the conductor, and an eddy current will be generated, and the eddy current and the magnetic field will work together to generate an eddy current torque. For rotating fragments in a constant magnetic field, this eddy current torque is of a racemic nature. The faster the conductor cuts the magnetic force lines, the greater the induced electromotive force formed in the conductor, and the greater the eddy current torque. However, since the movement speed of the debris itself is not fast, the generated eddy current is small, and its derotation torque is also small. In order to improve the efficiency of derotation, a rotating magnetic field for derotation can be set outside the rotating conductor fragments, so as to increase the relative movement speed of the fragments cutting magnetic force lines and improve the efficiency of derotation.

(2) Characteristics of the rotating derotation magnetic field

The rotating magnetic field used for derotation can be a single magnetic field or a synthetic magnetic field, and the final derotation magnetic field is a vector, that is, its basic characteristics are: first, the amplitude of the magnetic field strength is constant; second, the magnetic field The vector rotates in space, the main axis of the rotation coincides with the main axis of the debris rotation, and the rotation direction is opposite to the rotation direction of the debris.

(3) Generation method of rotating magnetic field

There are two ways to generate a rotating magnetic field. One is to use mechanical motion to form a rotating magnetic field. A power device is installed on the constant magnetic field generating device, so that the magnetic field generating device and the fragments rotate coaxially, and the direction is opposite to generate a rotating magnetic field. The second is to use alternating current to form a rotating magnetic field. Through a specific form of magnetic field generating device, alternating currents with different phases are passed through different coil windings, so that it forms a constant amplitude in space and changes with time to form a space that is the same as the main axis of rotation of the fragments and opposite to the direction of rotation. rotating magnetic field. Its rotational speed is related to the frequency of the alternating current.

This embodiment discusses the rotating magnetic field used for derotation. The structure of the fragments does not affect the magnetic field. For the convenience of description, the shape of the fragments is selected as a hollow cylinder, and the main axis of rotation is located on the centerline of the cylinder, rotating counterclockwise. Select a section perpendicular to the cylinder to establish a Cartesian coordinate system, the origin is the center of the section circle, and take any two perpendicular directions to establish the x-axis and y-axis. The form of the Cartesian coordinate system and the movement direction of the fragments are shown in Figure 1.

The synthetic magnetic field vector of the rotating magnetic field used for derotation rotates in space, and the main axis of the rotating motion coincides with the main axis of the debris rotating motion, the direction of rotation is opposite to that of the debris, and the amplitude of the magnetic field intensity is constant. Its form of expression can be expressed in Figure 2. Figure 2(a) The arrow representing the magnetic field intensity vector rotates at a constant speed, the axis of rotation coincides with the main axis of the fragments' rotational motion, and the direction of rotation is clockwise, which is opposite to the direction of the fragments' rotational motion. Since the magnitude of the magnetic field strength is constant, the trajectory at the end of the arrow is a circle. In the plane coordinate system of Fig. 2(b), the rotating magnetic field strength appears as a straight line parallel to the time axis.

In order to form the above-mentioned rotating magnetic field, a mechanical control method or a current control method may be used.

The mechanical control method is mainly to use the mechanical power device to drive the magnetic field generating device to perform rotational motion, the main axis of the rotational motion coincides with the main axis of the rotational motion of the fragments, and the direction of rotation is opposite. It can be shown in Figure 3. As shown in Figure 3, the debris rotates counterclockwise along its main axis of motion with a speed of ω. The magnetic field generating device uses N and S magnetic poles to represent the single or synthetic magnetic field generated. The amplitude of the magnetic field is constant. The device drives the movement to rotate, and its main axis of movement coincides with the main axis of the rotational movement of the fragments, and it rotates clockwise along the trajectory shown by the outer dotted line at a speed of _ω1 . The magnetic field formed at this time is the aforementioned rotating magnetic field for derotation.

The current control method is different according to the different magnetic field generating devices. Here, only the method of two-phase alternating current is used as an example to illustrate the method of generating the rotating magnetic field, and the practical application is not limited to this method. The magnetic field generating device using two-phase alternating current consists of two sets of coils perpendicular to each other, and its structure is shown in Figure 4.

In the two coils, the input amplitude is the same, and the alternating current with a certain angle difference in phase, for the convenience of expression, the currents in the two coils are represented by i _A and i _B respectively, where i _A =I _M sin(ω ₁ t), i _B =I _M sin(ω ₁ t+θ), the magnetic fields formed by the two coils are B _A =B _M sin(ω ₁ t), B _B =B _M sin(ω ₁ t+θ). its synthetic magnetic field In order to ensure that the amplitude of the magnetic field B remains unchanged during the rotation process, ω ₁ t = 0 and Substituting the two moments into the magnetic field synthesis formula respectively, we can get It can be solved from this Since the direction of rotation of the magnetic field is opposite to that of the debris, take The magnetic field formed at this time is the rotating magnetic field for derotation. To further verify the rotation direction of the magnetic field, we take The four moments are analyzed separately. When ω ₁ t=0, B _A =0, B _B =-B _M ; when , B _A ＝B _M , B _B ＝0; when ω ₁ t＝π, B _A ＝0, B _B ＝B _M ; , B _A =-B _M , B _B =0. The directions of the current and the resultant magnetic field at each moment are shown in Fig. 5 . It can be seen from the figure that the amplitude of the synthesized magnetic field is constant, and the main axis of the moving debris is the axis, which is opposite to the moving direction of the debris and rotates clockwise with an angular velocity of ω ₁ .

Claims (1)

1. the method that a kind of pair of space unmagnetized metal fragment carries out racemization, it is characterised in that: rotating excitation field is applied to space The main shaft of unmagnetized metal fragment surrounding, the rotary motion of rotating excitation field is overlapped with the main shaft of fragment rotary motion, rotating excitation field Direction of rotation it is opposite with fragment direction of rotation；The magnetic field strength constant amplitude of the rotating excitation field；The rotating excitation field uses Mechanical driver unit drives field generator for magnetic to make rotating motion, and mechanical driver unit drives N magnetic pole and S magnetic pole to do rotation fortune Dynamic, motive spindle is overlapped with the rotary motion main shaft of fragment, the rotary motion direction in magnetic field and the rotary motion direction phase of fragment Instead；The field generator for magnetic is the N magnetic pole and S magnetic pole being oppositely arranged, and generates single magnetic field or resultant magnetic field；

Or the rotating excitation field is generated using the field generator for magnetic of current control mode；It sends out in the magnetic field of the current control mode Generating apparatus is multiple coils composition, wherein each coil diameter passes through fragment rotation axis, each adjacent two coil is in space In be in an angle, the size of angle can be different between different adjacent windings, and alternating current is passed through in each coil and generates friendship Varying magnetic field, the alternating magnetic field Vector modulation that all coils generate are the circular rotating field of a constant amplitude.