CN100429496C - Method and device for measuring jet thrust - Google Patents

Abstract

The invention relates to a measuring device for jet thrust, which comprises a first bracket vertically fixed on a base and a guide mechanism supported by the top end of a second bracket, a bearing set is set on the guide mechanism, and the support seat and the bearing set are fixed together. The thruster to be measured is fixed on the support base by screws; the force measuring mechanism includes a cantilever beam with a positioning hole at one end, and the fastener fixes the cantilever beam on the bracket through the positioning hole, and the upper end of the cantilever beam is suspended and higher than the support The sensor is attached to the surface of the cantilever arm, and the sensor is electrically connected to the external acquisition, processing and display system through the signal line. The jet thrust measurement device of the present invention does not depend on the operating feeling of the installation and debugging personnel, so it will not vary from person to person, and does not need complicated and meticulous calibration that cannot guarantee repeatability during each installation, so the accuracy of the experimental measurement results The repeatability is good, and the thrust measurement results under different operating parameters of the thruster are highly comparable.

Description

A method and device for measuring jet thrust

technical field

The invention relates to a jet thrust measurement method and a device thereof, in particular to a jet thrust measurement method and a device thereof for on-orbit spacecraft attitude control and orbit control.

Background technique

With the development of the times, the space control capability plays an increasingly crucial role in the security and development of a country. Chemical propellants are suitable for short-duration, high-thrust propulsion missions. Relatively speaking, electric rocket propulsion technology can obtain higher carrying efficiency, and is suitable for propulsion tasks with long-term, small and medium thrust, and high specific impulse. At present, for various purposes of satellites or spacecraft, in order to reduce weight and size, improve positioning accuracy, and extend operating life, the use of space electric propulsion technology has become an indispensable and effective way. Whether it is the development of the national economy, national security, or future scientific research on deep space, it is necessary to develop efficient space electric propulsion technology. This is because compared with traditional attitude control/orbit control chemical rockets, electric propulsion has the outstanding advantage of high specific impulse. Space electric propulsion technology can be roughly divided into: 1) electrothermal type, including resistance heating jet method and arc heating plasma jet method; 2) electrostatic acceleration type, such as ion thruster; 3) plasma propulsion type, including Hall thruster , pulse plasma thruster, magnetoplasma dynamic thruster and variable specific impulse magnetoplasma thruster. So far, hundreds of satellites in the world have used electric propulsion systems, accumulating a large amount of useful data. However, there is no comprehensive performance index of any kind of electric propulsion thruster in my country that reaches or is close to practical application.

Before any kind of electric propulsion thruster can really go to the sky, it must carry out a lot of performance research and reliability simulation experiments on the ground. Among them, the measurement of the thrust is essential, especially the accurate measurement of the thrust of the small-thrust thruster is very important. One of the characteristics of the thruster used for space electric propulsion is that the thrust is relatively small, so one of the key technologies for the ground test of the electric propulsion thruster is the small thrust measurement of the thruster. If the thrust cannot be measured, the basic performance of the thruster cannot be verified. Therefore, people have proposed various force measuring devices with different principles, such as inverted pendulum type, double pendulum type, torsion pendulum type, multi-arm type and other measurement methods; Consistent) force measurement method, or do some center of gravity balance processing or compensation on the basis of sitting up; there is also a measurement method based on the principle of laser interferometry. These methods all have very high requirements for setting, debugging and calibration, especially some measurement methods that require counterweight and center of gravity adjustment, which require structural design and debugging of thrust thrusters of different types, weights and shapes, and the same measuring instrument For thrusters of the same shape and weight, incalculable measurement errors will also occur due to small changes that are difficult to grasp each time they are debugged. In this case, it is meaningless to propose a certain measurement principle or the accuracy or measurement error of the dynamometer in practical application. The fundamental reason why the small thrust of the electric propulsion thruster is so difficult to measure is that the ground test is carried out in the gravitational field of the earth, and the characteristic of the electric propulsion thruster is that its own weight is much greater than the thrust it generates. Electric rockets have been sent to space abroad for measurement, but such measurement must be very expensive and unbearable for the development of electric thrusters. In addition, the power supply system, air supply system, thruster itself heats up, and the vacuum environment of the measurement also has a great influence on the thrust measurement. Therefore, people have been looking for an ideal high-precision jet thrust measurement method.

Contents of the invention

The purpose of the present invention is to overcome the defect that the existing force measurement principle requires high debugging and calibration when measuring jet thrust, and is prone to measurement errors, to provide a simple force measurement method, and to provide a method for realizing the method measuring device.

The measuring device that realizes this method comprises: base 15, and the first support 1 that is vertically fixed on base 15, the second support 14, and force-measuring mechanism; Force-measuring mechanism comprises the sensor 11 that is connected with signal line 13, one end The cantilever beam 10 with the positioning hole 24, the force-measuring support 21 fixed on the upper end of the cantilever beam 10, and the fastener 12 that fixes the cantilever beam 10 on the support through the positioning hole 24. The upper end of the cantilever beam 10 is suspended and higher than the support base 3 , and the sensor 11 is attached to the surface of the cantilever arm 10 , and is electrically connected to an external acquisition, processing and display system through a signal line 13 . The measuring device is characterized in that it also includes a thruster carrying platform and a fixed positioning mechanism composed of a guide mechanism 2, a bearing group 16, and a support base 3; wherein the first bracket 1 and the second bracket 14 support the guide mechanism 2 at the top, The movement of the bearing group 16 is restricted by the guide mechanism 2 , the support seat 3 and the bearing group 16 are fixed together, and the thruster 6 whose thrust is measured is fixed on the support seat 3 .

In the above technical solution, the sensor 11 may be a stress gauge. Yet another technical solution is that the sensor 11 is an eddy current induction displacement sensor.

In the above technical solution, the bearing group is composed of more than two bearings, which are mutually positioned by the guide mechanism 2 and connected with the support seat 3 . Make the supporting seat 3 loaded with the thruster 6 reach stability and balance.

In the above technical solution, the guide mechanism 2 makes the bearing group 16 move linearly in a certain direction, the moving direction is parallel to the thrust direction, and the horizontal sliding resistance between the bearing group 16 and the guide mechanism 2 is less than 1mN.

In the above technical solution, the support base 3 loaded with the thruster, such as a trolley for directional linear translation, moves in a direction perpendicular to the force-measuring cantilever beam.

In the above technical solution, the shape design of the support seat can realize that the thrust direction of the thruster is parallel to the moving direction of the bearing group while locking the thruster.

In the above technical solution, the levelness of the base 15 is adjusted so that the angle between the thrust direction and the gravity direction is equal to or slightly smaller than 90 degrees, and the additional resistance generated by gravity when sliding along the thrust direction is eliminated.

The advantages of the present invention are:

1. Since the thruster of the electric propulsion rocket is fixedly connected to the bearing group, as long as the bearing with the appropriate size and carrying capacity is selected according to the weight and size of the thruster during production, the processing and matching dimensions are reasonable, and the sliding resistance of the bearing is adjusted to the minimum during assembly, The thruster support base is like a stable vehicle seat installed on a slide rail with minimal resistance. When the thruster is fixed to the vehicle seat, it is not required to pay attention to the adjustment of the position of the center of gravity of the thruster and the balance of the fuselage. It is only necessary to ensure that the thrust Parallel to the sliding direction of the linear bearing, high-precision measurement can be realized.

2. The condition to ensure that the thrust (that is, the axis of the thruster) is parallel to the guiding mechanism of the bearing group is that when designing the support seat, bracket and guiding mechanism, the positioning restrictions during consolidation are considered according to the structure of the thruster, so it is not necessary It depends on the operating feeling of the installation and commissioning personnel, so it will not vary from person to person, and there is no need for complicated and meticulous calibration that cannot guarantee repeatability during each installation. Therefore, the repeatability of the experimental measurement results is good, and the thrusters are different. Thrust measurements are highly comparable across operating parameters.

Description of drawings

Fig. 1 is the structural representation of jet thrust measuring device of the present invention;

Fig. 2 is a schematic diagram of the relationship between the sensor and the cantilever beam when the sensor of the present invention selects a stress strain gauge;

Fig. 3 is when the sensor of the present invention selects the eddy current induction sensor, the schematic diagram of the relationship between the sensor and the cantilever beam;

Fig. 4 is a schematic diagram of the thrust calibration and verification system of the present invention.

Illustration

1 First bracket 2 Guide mechanism 3 Support seat 4 High-speed airflow 5 Arrow

6 Thruster 7 Supply air path 8 Power cord 9 Head 10 Cantilever beam

11 Sensor 12 Fastener 13 Signal Line 14 Second Bracket 15 Base

16 Bearing group 21 Force measuring support 24 Positioning hole 30 Connecting piece 31 Force transmission piece

33 Displacement sensor 37 Optical fiber 38 Precision bearing 39 Shaft 40 Weight

Detailed ways

The jet thrust measuring device of the present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

Example 1:

With reference to Fig. 1, make a measuring device of jet thrust of the present invention. The first bracket 1 and the second bracket 14 are fixed on the base 15 , and the top ends of the first bracket 1 and the second bracket 14 support a guide mechanism 2 . The bearing set 16 and the guide mechanism 2 form a kinematic pair, the support base 3 and the bearing set 16 are fixed together, and the thruster 6 whose thrust is to be measured is fixed on the support base 3, so as to realize the fixation with the bearing set 16. The support base 3 is made of a material with good heat insulation.

As shown in Figure 2, a metal strip is used as the cantilever beam 10, and one end of the cantilever beam 10 of the metal strip has a positioning hole 24, and the fastener 12 fixes the cantilever beam 10 on the second support 14 through the positioning hole 24, also It can be fixed on the first bracket 1, and the fastener 12 can be fixed on different positions on the bracket, so as to be suitable for thrust measurement of thrusters of different sizes. The sensor 11 of this embodiment uses a stress strain gauge, and the stress strain gauge is attached to the surface of the cantilever arm 10. The stress strain gauge is electrically connected to the external collection, processing and display system through the signal line 13, and the stress strain gauge senses the cantilever arm 10. amount of deformation.

When utilizing the measuring device of the jet thrust of the present invention to measure the jet thrust of the thruster, the thruster 6 is fed into the thruster propellant by the gas supply path 7, and the power supply line 8 supplies power to the thruster so as to heat the propellant. During operation, the nozzle of thruster 6 ejects high-temperature and high-speed airflow 4, and simultaneously produces thrust in the direction shown by arrow 5 to the thruster, as shown in Figures 1 and 2, the thrust acts on the thruster through the plug 9 fixed to thruster 6 Measuring device The force-measuring support 21 on the suspended end of the cantilever beam 10 . The cantilever beam 10 deforms under the action of the thrust, and the strain gauge senses the deformation, outputs an electrical signal and converts it into a voltage corresponding to the force through the signal line 13 through the circuit board, and displays it as a force reading through the digital tube.

Example 2:

As shown in Figure 1, make a jet thrust measuring device of the present invention. A base 15 is made, on which the first support 1 and the second support 14 are fixed, and the top ends of the first support 1 and the second support 14 support the guide mechanism 2 . The bearing set 16 and the guide mechanism 2 form a kinematic pair, the support base 3 and the bearing set 16 are fixed together, and the thruster 6 whose thrust is measured is fixed on the support base 3 by screws, so as to realize the fixation with the bearing set 16 . The support base 3 is made of a material with good heat insulation. As shown in Figure 2, a positioning hole 24 is arranged on one end of the cantilever beam 10, and the fastener 12 fixes the cantilever beam 10 on the second bracket 14 through the positioning hole 24, and the fastener 12 can be fixed to different parts of the second bracket 14. Position, measured in thrust for thrusters of different sizes. There is a sensor 11 near the suspension end of the cantilever arm 10, and the sensor 11 is an eddy current induction displacement sensor.

Utilize the measuring device of jet thrust of the present invention to measure the jet thrust of thruster, before measuring, as shown in Figure 3, thruster 6 is fixed with one end of force transmission part 31 by connector 30, the other end of force transmission part 31 One end is connected with the displacement sensor 33 . The eddy current induction displacement sensor should be aligned with the displacement sensing element 33 during installation, and there is a certain distance between them. During measurement, the thruster 6 is supplied with the propellant of the thruster by the air supply circuit 7, and the power supply is supplied to the thruster by the power line 8. The propellant is heated in the thruster 6 and sprayed out by the nozzle to form a high-temperature and high-speed airflow 4, and at the same time, the thruster generates The thrust in the direction shown by the arrow 5, the thrust acts on the cantilever beam 10 through the force transmission member 31, and the cantilever beam 10 is deformed under the action of the thrust, so that the displacement sensor 33 connected to the force transmission member 31 produces a force parallel to the direction of action of the force. The movement of the displacement sensor 33 and the gap between the eddy current induction sensor changes, the gap change is sensed by the eddy current induction sensor and converted into an electrical signal, and then transmitted to the signal processing circuit board through the signal line 13, according to the output voltage of the circuit board The magnitude of the force can be obtained from the calibration relationship.

Example 3:

Fig. 4 is the static calibration schematic diagram of the measuring device of jet thrust of the present invention, and the center of thruster 6 forms aperture, and 200 micron diameter optical fiber 37 one ends are fixedly connected in thruster nozzle, and the other end runs through aperture and electric thrust thruster 6 Axle hole, and pass through from top 9, cantilever beam 10, ride on precision bearing 38 at last. The center of the precision bearing 38 is fixed on the shaft 39, and the shaft 39 is fixed on the base 15 of the measuring device. The end of the optical fiber close to the precision bearing 38 is installed with a detachable weight 40, and the same thrust as the gravity of the weight 40 is as follows: Arrow 5 acts on the cantilever beam 10 , and the sensor 11 detects the force acting on the cantilever beam 10 . The jet thrust measuring device of the present invention can be calibrated by comparing the force measured by the sensor with the gravity of the weight 40 .

Claims (6)

1. A measuring device for jet thrust, comprising: a base (15), and a first support (1), a second support (14) vertically fixed on the base (15), and a force-measuring mechanism; The mechanism includes a sensor (11) connected with a signal line (13), a cantilever beam (10) with a positioning hole (24) at one end, and a force-measuring support (21) fixed on the upper end of the cantilever beam (10). Holes (24) fix the cantilever beam (10) on the fastener (12) on the support; the upper end of the cantilever beam (10) is suspended and higher than the support seat (3), and the sensor (11 ) is attached to the surface of the cantilever arm (10) and is electrically connected to the external acquisition, processing and display system through the signal line (13); it is characterized in that it also includes a guide mechanism (2), a bearing group (16), a support seat (3) The thruster carrying platform and fixed positioning mechanism that form; Wherein said first support (1) and second support (14) top support described guide mechanism (2), and bearing group (16) is by guide mechanism ( 2) Restricting the movement, the support seat (3) and the bearing group (16) are fixed together, and the thruster (6) whose thrust is measured is fixed on the support seat (3). 2. The jet thrust measuring device according to claim 1, characterized in that: the bearing group is composed of more than two bearings, which are positioned with each other by a guide mechanism and connected with the support base. 3. The jet thrust measuring device according to claim 2, characterized in that: the guide mechanism makes the bearing group move linearly in a certain direction, the moving direction is parallel to the thrust direction, and the horizontal sliding resistance between the bearing group and the guide mechanism Less than 1mN. 4. The jet thrust measuring device according to claim 2, characterized in that: the supporting seat loaded with the thruster is a trolley that is oriented and linearly translated, and the moving direction is perpendicular to the force-measuring cantilever beam. 5. The device for measuring jet thrust according to claim 2, characterized in that: the topography of the support seat is designed so that the thrust direction of the thruster is parallel to the moving direction of the bearing group while locking the thruster. 6. The device for measuring jet thrust according to claim 1, characterized in that: adjust the horizontal adjustment mechanism of the base so that the angle between the direction of thrust and the direction of gravity is equal to or slightly less than 90 degrees, and when the elimination mechanism slides along the direction of thrust, the Additional resistance due to gravity.

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