Triboelectrification equivalent simulation and measurement device for AP particle pot entering process

Abstract

The invention discloses a contact separation triboelectrification equivalent simulation and measurement device for a solid engine AP particle pot entering process, and relates to a solid engine propellant oxidant feeding production process safety technology and a static electricity generation and release simulation and measurement technology. The device is mainly composed of a funnel, a flow control valve, a height adjusting device, a Rogowski coil, an electrostatic measuring instrument array, a Faraday cup, a high-speed picoammeter, a high-speed camera and a computer. A simulation device composed of a funnel, a flow control valve and a height adjusting device controls the flow and height of particles at an outlet of the funnel, and simulates the triboelectrification process of the AP particles entering a pot. A measuring device consisting of a Rogowski coil, an electrostatic measuring instrument array, a Faraday cup and a high-speed picoammeter is used for measuring the charge characteristics of the particles in different stages; the high-speed camera assists in collecting particle dynamic parameters, and finally the friction electrification process simulation and charge characteristic measurement of the particle pot entering process are integrally achieved.

Description

Technical Field

[0001] The present invention relates to solid motor propellant oxidizer feeding production process safety technology, static electricity generation and release simulation and measurement technology, and in particular to particle contact and separation friction electrification simulation and measurement technology with controllable free fall height and flow. Background Art

[0002] In recent years, with the rapid development of solid rocket engine technology, the preparation and use of solid propellants have increased day by day. In the production process of solid propellants, there are a large number of flammable and explosive materials that need to be screened, transported, mixed, trimmed, and tested. Therefore, explosions may occur under external stimulation, causing casualties, equipment damage, and house damage. It is precisely because of the huge accidental destructiveness of solid propellants that countries have attached great importance to the safety research of solid propellants and engines. In addition to "obvious" dangerous sources such as heat, machinery, and shock waves, there is also a more "hidden" dangerous source - static electricity. The accumulation and discharge of static electricity are invisible to the human eye, but the harm caused is also very huge. In recent years, although countries have continuously increased their attention to the safety of composite propellant production processes and continued to deepen their research, the physical research methods and devices for the contact separation friction charging process of ammonium perchlorate (AP) particles in the free fall stage of the pot process are still immature, and the influence of different pot heights and flow rates on the charging characteristics of particles is still unclear. Therefore, solid engine safety accidents caused by static electricity in the AP particle pot stage have not been effectively controlled. Summary of the invention

[0003] The present invention discloses an equivalent simulation and measurement device for contact separation friction electrification of solid rocket AP particles during the process of entering a pot, and the main technical problem solved is to simulate the physical process of contact separation friction electrification of AP particles during the process of entering a pot.

[0004] The purpose of the present invention is achieved through the following technical solutions.

[0005] A friction electrification equivalent simulation and measurement device for a process of AP particles entering a pot comprises a funnel, a flow control valve, a height adjustment device, a Rogowski coil, an electrostatic measuring instrument array, a high-speed camera, a Faraday cup, a high-speed picoammeter, and a computer.

[0006] According to one aspect of the present invention, the height adjustment device controls the adjustment of the vertical height of the funnel, and the adjustment range is 100-600mm; and / or the flow control valve at the funnel outlet controls the funnel outlet flow to be continuously adjustable within the range of the control valve diameter from fully open to fully closed.

[0007] According to one aspect of the present invention, the process of obtaining the initial current value of the initial stage of the electrostatic particles flowing out of the funnel by the Rogowski coil is as follows:

[0008] The Rogowski coil is placed at the exit of the funnel, and the charged particles fall freely through the middle of the coil. The Rogowski coil is based on the principle of electromagnetic induction, that is, a time-varying electric field will generate a time-varying magnetic field around it. According to Faraday's electromagnetic induction theorem, the measured current is formula (1):

[0009]

[0010] Where N is the number of coil turns, d is the coil diameter, D is the coil diameter, and μ is the magnetic permeability. The measured current is proportional to the integral of the mutual inductance. In order to accurately restore the waveform of the measured current signal, the induced electromotive force of the coil must be transformed through the integration circuit. The integration circuit uses an RC passive external integration network. R1 is a sampling resistor, which is generally less than one tenth of the integration resistor R to ensure that the measurement circuit is close to a pure resistance network; R2 is a filter resistor, which forms a low-pass filter system with the oscilloscope distributed capacitance to reduce high-frequency interference clutter. After passing through the above external integration circuit, ignoring the voltage drop of the coil inductance and stray resistance, the output signal is formula (2):

[0011]

[0012] According to one aspect of the present invention, the electrostatic measuring instrument array uses a group of electrostatic measuring instruments vertically arranged at different positions below the funnel outlet to measure the voltage of particles moving to a specified position and the temperature and humidity of the particles with high precision within the range of ±50kV.

[0013] According to one aspect of the present invention, the Faraday cup cooperates with the high-speed picoammeter to obtain a current variation curve.

[0014] The invention provides a method for equivalent simulation and measurement of a contact and separation friction electrification equivalent simulation and measurement device for a solid engine AP particle entering a boiler process. First, the particles are placed in a funnel, and the funnel height and particle outlet flow are controlled by a flow control valve and a height adjustment device. During the free fall of the particles, the particles and the funnel, and between the particles, contact and separate friction electrification to accumulate static charge. The charged particles freely fall through the middle of the Rogowski coil to obtain the initial current value of the initial stage of the statically charged particles flowing out of the funnel. Subsequently, during the falling process, the electrostatic measuring instrument array can measure and record the voltage and humidity of the AP particles when they move to different vertical positions. A high-speed camera and image processing software can track the particle trajectory and derive the particle speed, position and other parameters. Then, the charged AP particles fall into a Faraday cup at the lower end, and the Faraday cup is connected to a high-speed picoammeter with a kHz sampling rate to obtain the static dynamic accumulation characteristic I=dQ / dt after the particles are frictionally electrified. Finally, the data is imported into a computer for processing.

[0015] As can be seen from the above, the present invention has the following beneficial effects:

[0016] 1. The present invention discloses a contact separation friction electrification equivalent simulation and measurement device for the solid engine AP particle entering the pot process. A high-precision Rogowski coil is set at the funnel outlet to measure the initial current value of the initial stage when the electrostatic particles flow out of the funnel.

[0017] 2. The present invention discloses a contact and separation friction electrification equivalent simulation and measurement device for the solid engine AP particle entry process, which has two adjustment types: height and flow. The height is adjustable in the range of 100-600mm, and the flow is adjustable in the range of 40mm diameter of the control valve from fully open to fully closed, thereby realizing an experimental simulation process with one more parameter.

[0018] 3. The present invention discloses a contact and separation friction electrification equivalent simulation and measurement device for the solid rocket engine AP particle entering the pot process. An electrostatic measuring instrument array is longitudinally arranged between the funnel outlet and the Faraday cage to measure the charging characteristics of particles at different heights in real time during the falling process.

[0019] 4. The present invention discloses an equivalent simulation and measurement device for contact and separation friction electrification of solid rocket engine AP particles during the process of entering the pot. A high-speed picoammeter is introduced for use in conjunction with a Faraday cup. After connecting to a data acquisition instrument, a current change curve is obtained, thereby realizing the dynamic process collection of particle electrostatic accumulation.

[0020] 5. The present invention discloses an equivalent simulation and measurement device for the contact and separation friction electrification process of solid engine AP particles entering the pot, which is suitable for simulating the contact and separation friction electrification process of particles in free fall, and meets the requirements of adjustable flow rate and height and real-time parameter measurement. It can be applied to the analysis of the charging characteristics of various powders and particles in the free fall process.

[0021] Other features and advantages of the present invention will be described in further detail below. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the equivalent simulation and measurement device for contact and separation triboelectric charging during the AP particle feeding process of solid rocket motor;

[0023] Figure 2 It is a three-dimensional schematic diagram of the funnel, flow control valve and height adjustment device;

[0024] Figure 3 It is a schematic diagram of the funnel and flow control valve structure;

[0025] Figure 4 This is the circuit diagram of the Rogowski coil;

[0026] Among them: 1-funnel, 2-flow control valve, 3-height adjustment device, 4-Rogowski coil, 5-electrostatic measuring instrument array, 6-high-speed camera, 7-Faraday cup, 8-high-speed picoammeter, 9-computer. DETAILED DESCRIPTION

[0027] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0028] As attached Figure 1-3 As shown, the present invention provides a set of contact separation friction electrification equivalent simulation and measurement device for solid engine AP particle entering pot process, the device includes a funnel 1, a flow control valve 2, a height adjustment device 3, a Rogowski coil 4, an electrostatic measuring instrument array 5, a high-speed camera 6, a Faraday cup 7, a high-speed picoammeter 8, a computer 9 and supporting circuits.

[0029] Taking μm-sized AP particles as an example, the AP particles are placed in a funnel 1, and the funnel height and particle outlet flow rate are controlled by a flow control valve 2 and a height adjustment device 3; during the free fall of the particles, the particles and the funnel, and between the particles, are contacted and separated by frictional charging to accumulate static charge; the charged particles freely fall through the middle of the Rogowski coil 4, and the initial current value of the initial stage of the statically charged particles flowing out of the funnel is obtained; subsequently, during the falling process, the electrostatic measuring instrument array 5 can measure and record the voltage and humidity of the AP particles when they move to different vertical positions; the high-speed camera 6 cooperates with the image processing software to track the particle trajectory and derive the particle's speed, position and other parameters; then the charged AP particles fall into the Faraday cup 7 at the lower end, and the Faraday cup 7 is connected to a high-speed picoammeter 8 with a kHz sampling rate to obtain the static dynamic accumulation characteristic I=dQ / dt after the particles are frictionally charged; finally, the data is imported into a computer 9 for processing.

[0030] Specifically, the simulation device as a whole is composed of two parts; the first part is used to control the AP particle flow rate and free fall height, and the second part is used to measure the particle charge characteristics of the free fall part. The first part is composed of a funnel and a height adjustment device. The funnel is, for example, a 90° cone angle, and a flow control valve is installed at the lower outlet. The outlet diameter is, for example, 40 mm, which is used to control the particle outlet flow rate and can be completely closed and fully opened; the funnel is fixed to the height adjustment device by bolts; the height adjustment device is composed of a bracket and a displacement mechanism fixed to the side of the bracket; the displacement mechanism is composed of a motor and a displacement shaft, which can drive the funnel to move vertically within the range of 100-600 mm.

[0031] A Rogowski coil 4 is installed below the funnel outlet, and the particles fall from the coil to monitor the initial current value of the initial stage of the static-charged particles flowing out of the funnel; a group of new SK series static meters are installed vertically below the Rogowski coil as a static meter array 5, which can measure the voltage of the particles moving to the specified position and the temperature and humidity of the particles with high precision within the range of ±50kV; a Faraday cup is placed below the static meter array, and a high-speed picoammeter is connected to it. The present invention uses the 6487 series high-speed picoammeter of Tektronix products, and the high-speed picoammeter with a kHz sampling rate is matched with a Faraday cup to measure the static electricity and current of the particles; a high-speed camera 6 is placed on the other side of the static meter array 5. The present invention uses a Phantom TMX 7510 high-speed camera to shoot the behavior of the particles. The camera has a speed of up to 76,000 frames per second at a resolution of 1280*800. The image sequence obtained by shooting can be processed by photron image processing software to track the particle trajectory and derive the parameters such as the particle speed and position.

[0032] like Figure 4 As shown, in order to accurately restore the waveform of the measured current signal, the induced electromotive force of the coil must be transformed through the integration circuit. The integration circuit uses an RC passive external integration network, R1 is a sampling resistor, and its value is generally less than one tenth of the integration resistor R to ensure that the measurement circuit is close to a pure resistance network; R2 is a filter resistor, which forms a low-pass filter system with the oscilloscope distributed capacitor to reduce high-frequency interference clutter.

[0033] By using the Faraday cup 7, the amount of charge carried by the particles after friction can be grasped, and by using the high-speed picoammeter 8, the dynamic process of static electricity accumulation can be grasped.

[0034] The specific description above further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A friction-electrification equivalent simulation and measurement device for the process of AP particles entering a pot, characterized in that: The device comprises a funnel (1), a flow control valve (2), a height adjustment device (3), a Rogowski coil (4), an electrostatic measuring instrument array (5), a high-speed camera (6), a Faraday cup (7), a high-speed picoammeter (8), and a computer (9).

2. The device for simulating and measuring triboelectric equivalent of AP particles entering a pan as claimed in claim 1, characterized in that: The height adjustment device (3) controls the vertical height adjustment of the funnel (1), and the adjustment range is 100-600 mm; and / or The flow control valve (2) at the funnel outlet controls the flow at the funnel outlet to be continuously adjustable within the range of the control valve diameter from fully open to fully closed.

3. The device for simulating and measuring triboelectric equivalent of AP particles entering a pan as claimed in claim 1, characterized in that: The Rogowski coil (4) is a high-precision Rogowski coil horizontally placed below the funnel outlet. It can measure the initial value of the current i at the initial stage of the electrostatically charged particles flowing out of the funnel according to the following formulas (1) and (2): Where N is the number of coil turns, d is the coil diameter, D is the coil diameter, μ is the vacuum magnetic permeability, e(t) is the induced electromotive force of the Rogowski coil, and the measured current is proportional to the integral of the mutual inductance. In order to accurately restore the waveform of the measured current signal, the induced electromotive force of the coil must be transformed through an integration circuit. The integration circuit uses an RC passive external integration network. After passing through the above external integration circuit, ignoring the voltage drop of the coil inductance and stray resistance, the output signal is formula (2): Where u is the result of the induced electromotive force of the Rogowski coil after passing through the RC integration circuit and then output on the oscilloscope.

4. The device for simulating and measuring triboelectric equivalent of AP particles entering a pan as claimed in claim 1, characterized in that: The electrostatic measuring instrument array (5) uses a group of electrostatic measuring instruments vertically arranged at different positions below the funnel outlet, and is used to measure the voltage of the particles moving to the specified position and the temperature and humidity of the particles with high precision within the range of ±50kV.

5. The device for simulating and measuring triboelectric equivalent of AP particles entering a pan as claimed in claim 1, characterized in that: The Faraday cup cooperates with the high-speed picoammeter to obtain a current variation curve.

6. A method for performing equivalent simulation and measurement based on the triboelectric equivalent simulation and measurement device for AP particle entering a pot process according to claim 1, 2, 3, 4 or 5, characterized in that: First, the particles are placed in a funnel, and the height of the funnel and the particle outlet flow rate are controlled by a flow control valve and a height adjustment device; during the free fall of the particles, the particles and the funnel, and between the particles, are contacted and separated, and frictionally charged to accumulate static charge; the charged particles freely fall through the middle of the Rogowski coil, and the initial current value of the initial stage of the statically charged particles flowing out of the funnel is obtained; subsequently, during the falling process, the electrostatic measuring instrument array can measure and record the voltage and humidity of the AP particles when they move to different vertical positions; the high-speed camera and image processing software can track the particle trajectory and derive the particle's speed, position and other parameters; then the charged AP particles fall into the Faraday cage at the lower end, and the Faraday cage 7 is connected to a high-speed picoammeter with a kHz sampling rate to obtain the static dynamic accumulation characteristics I=dQ / dt after the particles are frictionally charged; finally, the data is imported into a computer for processing.

Images