Arc spot position and rotating speed testing device and testing method of electric arc heater

Abstract

This invention belongs to the field of arc heater technology and discloses a testing device and method for testing the arc spot position and rotation speed of an arc heater. During the test, a wireless data acquisition device, powered by a battery, is installed on the high-voltage rear electrode of the arc heater. The wireless data acquisition device is electrically isolated from other components and the ground. Several thermocouples are installed at equal intervals along the axis on the cathode wall of the inner shell of the electrode. The thermocouple wires are connected to the wireless data acquisition device through a cooling channel. After acquiring the temperature value, the wireless data acquisition device transmits it to the wireless AP in the test hall via a wireless transmitter, and then to the industrial control computer. Based on the obtained temperature value, the operator determines the axial coordinate of the arc spot, determines the rotation speed of the arc spot, calculates the heat flux value of the arc spot, and captures motion images of the arc spot. The testing device and method provide data support for the control of the arc spot position and rotation speed of the arc heater, thereby improving electrode lifespan and reducing the operating cost of the arc heater.

Description

Technical Field

[0001] This invention belongs to the field of arc heater technology, specifically relating to a device and method for testing the arc spot position and rotation speed of an arc heater. Background Technology

[0002] Arc heaters are crucial equipment for simulating the thermal environment of hypersonic vehicles. They utilize electric arc discharge to heat air, creating a high-temperature gas flow that then heats the target material or test model. During operation, the high voltage and current of the electrodes cause significant electrode burn-out. Therefore, controlling the arc spot position, rotation speed, and analyzing heat transfer within the arc spot are essential for extending electrode life, improving test reliability, and reducing test costs.

[0003] Because the electrodes of the arc heater carry high voltage, it is difficult to test the parameters on the electrodes. The high temperature, high pressure, and strong radiation inside the arc tube also make it difficult to determine the position of the arc spot and the speed of rotation, which brings great difficulties to the study of ablation of the arc heater electrodes.

[0004] Currently, there is an urgent need to develop a testing device and method for testing the arc spot position and rotation speed of an electric arc heater. Summary of the Invention

[0005] One technical problem to be solved by the present invention is to provide a device for testing the arc spot position and rotation speed of an electric arc heater. Another technical problem to be solved by the present invention is to provide a method for testing the arc spot position and rotation speed of an electric arc heater, so as to realize quantitative measurement of the arc spot.

[0006] The arc heater arc spot position and rotation speed testing method of the present invention uses an arc heater arc spot position and rotation speed testing device comprising a cathode, an insulating ring and an anode connected sequentially from front to back, a housing is fitted over the cathode, insulating ring and anode, and a cooling pipe is provided between the cathode, insulating ring and anode and the housing;

[0007] An observation glass is installed inside the end face on the left side of the outer casing, and a high-speed camera is positioned to take pictures of the observation glass. A wireless signal collector is installed on the outer wall of the left side of the outer casing, and a magnetic field coil is installed on the outer wall of the middle section of the outer casing.

[0008] Several heat transfer ribs are evenly distributed circumferentially on the tube wall of the cathode. Several thermocouples are installed at equal intervals from front to back on one of the heat transfer ribs A. The starting thermocouple is the left end thermocouple, and the ending thermocouple is the right end thermocouple. The left end thermocouple is located to the left of the magnetic field coil, and the right end thermocouple is located to the right of the magnetic field coil. The thermocouple connecting wires of all thermocouples converge into a single strand and are led out from the thermocouple wire outlet located on the left side of the outer shell through a cooling pipe, and connected to the wireless signal acquisition device.

[0009] The method includes the following steps:

[0010] S10. Establish signal acquisition and transmission channels;

[0011] Connect the thermocouple wires to the signal isolator, connect the signal isolator to the wireless signal acquisition device, connect the wireless signal acquisition device to the wireless AP in the test hall, and connect the wireless AP to the industrial control computer.

[0012] S20. Start the test and generate an electric arc;

[0013] When the equipment is powered on, an electric arc is generated in the cavity that runs through the cathode, insulating ring, and anode.

[0014] S30. Data processing;

[0015] S31. Data transmission;

[0016] The wireless signal acquisition device collects the temperature value of the thermocouple, transmits it to the wireless AP in the test hall through the wireless transmitter, and then transmits it to the industrial control computer.

[0017] S32. Determine the axial coordinates of the arc spot;

[0018] Since the temperature at the arc spot location is higher than that at the non-arc spot location, the arc spot location is determined by the fact that the temperature values ​​of two adjacent thermocouples are greater than the temperature values ​​of the remaining thermocouples. The specific steps are as follows:

[0019] Let the axial coordinate of the arc spot be... The highest temperature at the arc root is ;

[0020] Select the three thermocouples with the highest and closest temperatures, with temperatures of respectively , , The corresponding coordinate values ​​are respectively , , ,and < < Because the arc spot area is small and the temperature is high, the temperature at the non-arc spot location drops sharply relative to the arc spot. In order to predict the arc spot location, we assume... The temperature distribution exhibits a linear, triangularly symmetrical pattern; the higher the thermocouple temperature, the closer it is to the arc spot. Let the distance between the two thermocouples be... ;

[0021] Determining the axial coordinates of the arc spot can be divided into the following three cases:

[0022] a. If = Then the axial coordinate of the arc spot is considered to be = ;

[0023] b. If Then it is assumed that the axial coordinate of the arc spot is in and between;

[0024] Since the temperature is assumed to be linearly distributed, the thermocouple temperature is inversely proportional to the distance from the arc spot, and the arc spot is related to the coordinate values. x 1 Thermocouple distance at point is d 1 , and coordinate values x 2 Thermocouple distance at point is d 2 Then we have:

[0025] ;

[0026] but:

[0027] ;

[0028] Arc spot axial coordinates Determined as:

[0029] ;

[0030] c. If > > Then it is assumed that the axial coordinate of the arc spot is in and between;

[0031] Since the temperature is assumed to be linearly distributed, the thermocouple temperature is inversely proportional to the distance from the arc spot, and the arc spot and... The distance between the thermocouples is ,and The distance between the thermocouples is Then we have:

[0032] ;

[0033] but:

[0034] ;

[0035] Arc spot axial coordinates Determined as:

[0036] .

[0037] Furthermore, the thermocouple is an armored thermocouple with exposed wires, and the radial distance between the front end of the wire and the inner wall of the cathode is 2mm~4mm.

[0038] Furthermore, the thermocouple is welded to the central axis of the screw, and the screw is fixed in the screw hole of the heat transfer rib.

[0039] Furthermore, a signal isolator is connected between the thermocouple and the wireless signal acquisition device.

[0040] Furthermore, several thermocouples are installed on the heat transfer rib A and the adjacent heat transfer rib B. The thermocouples on heat transfer rib B correspond one-to-one with the thermocouples on heat transfer rib A and have the same axial coordinates. The radial distance between the thermocouples on heat transfer rib A and the inner wall surface of the cathode is... The radial distance between the thermocouple on heat transfer rib B and the inner wall of the cathode is , .

[0041] Furthermore, the method also includes the following steps:

[0042] S33. Determine the rotation speed of the arc spot;

[0043] The arc spot rotates along the circumference, causing the temperature values ​​of each thermocouple to change periodically. The rotation speed of the arc spot is calculated based on the rate of periodic change. The magnetic field coil is adjusted in real time according to the rotation speed of the arc spot to reduce the ablation of the electrodes by the arc spot.

[0044] S34. Calculate the heat flux value of arc spot heating;

[0045] Using the thermocouples on heat transfer fin A and the adjacent heat transfer fin B, calculate the heat flux value for arc spot heating. q :

[0046] ;

[0047] in, The temperature value of the thermocouple on heat transfer fin A; The temperature value of the thermocouple on heat transfer rib B, which is at the same axial position as the thermocouple on heat transfer rib A. λ The thermal conductivity of the cathode material;

[0048] S35. Capture moving images of the arc spot;

[0049] A high-speed camera captures images of the moving arc spots by observing the glass.

[0050] The arc heater arc spot position and rotation speed testing device of this invention involves installing a wireless data acquisition unit on the high-voltage rear electrode of the arc heater during testing. The wireless data acquisition unit is battery-powered and electrically isolated from other components and the ground. Several thermocouples are installed at equal intervals along the axis on the cathode tube wall, and their wiring is connected to the wireless data acquisition unit through a cooling channel. After acquiring the temperature values, the wireless data acquisition unit transmits them wirelessly to a wireless access point (AP) in the test hall, and then to an industrial control computer. Based on the obtained temperature values, the operator analyzes the temperature values ​​of each thermocouple. Due to the extremely high temperature at the arc spot location, the temperature values ​​of two adjacent thermocouples are higher than those of the remaining thermocouples. The axial position of the arc spot is determined based on the axial coordinates of two adjacent thermocouples. Simultaneously, the arc spot rotates circumferentially, causing periodic changes in the temperature values ​​of each thermocouple. The rotation speed of the arc spot is calculated based on the rate of these periodic changes. A high-speed camera installed at the tail of the rear electrode can also capture images of the arc spot's motion, which are then compared and analyzed with the thermocouple test data.

[0051] The arc heater arc spot position and rotation speed testing device of the present invention has the following characteristics:

[0052] a. The use of wireless data acquisition and transmission solved the problem of the high voltage of the arc heater posing a threat to the measurement and control system;

[0053] b. Thermocouples are arranged on the heat transfer ribs of the cathode wall at equal intervals, in sufficient quantities, and close to the inner wall, so that each thermocouple can obtain the axial temperature distribution data of the inner wall of the cathode.

[0054] c. Select a small-diameter armored thermocouple with exposed wires to enable a rapid response to the test signal;

[0055] d. The thermocouple is welded to the central axis of the screw, and the screw is fixed in the screw hole of the heat transfer rib. The exposed thermocouple has tight contact, reliable testing, and rapid response.

[0056] e. A signal isolator is connected between the thermocouple and the wireless data acquisition unit to prevent interference signals from the arc heater from affecting the temperature value of the thermocouple;

[0057] f. Adjust the magnetic field in real time according to the rotation speed of the arc spot to reduce the ablation of the electrode by the arc spot.

[0058] The arc heater arc spot position and rotation speed testing device of the present invention installs a thermocouple on the cathode and uses a wireless data acquisition and transmission system to collect and transmit the temperature signal of the cathode to a computer. Combined with the periodic temperature changes caused by the rotational motion and the motion images collected by the high-speed camera at the tail, the arc spot position and rotation speed can be determined.

[0059] The arc spot position and rotation speed testing device and method of the present invention are applicable to parallel flow and can be used for determining the arc spot position, monitoring rotational motion and analyzing heat transfer in tubular or plate arc heaters. This provides data support for the control of arc spot position and rotation speed of arc heaters, thereby improving electrode lifespan and reducing the operating cost of arc heaters. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of the structure of the arc spot position and rotation speed testing device for the electric arc heater of the present invention;

[0061] Figure 2 This is a schematic diagram of the thermocouple installation in the arc spot position and rotation speed testing device of the electric arc heater of the present invention;

[0062] Figure 3 This is a schematic diagram of the thermocouple structure in the arc spot position and rotation speed testing device of the electric arc heater of the present invention;

[0063] Figure 4 This is a flowchart illustrating the signal acquisition and transmission process of the arc spot position and rotation speed testing device for the electric arc heater of the present invention.

[0064] Figure 5a This is a schematic diagram of the arc spot position predicted by the arc spot position and rotation speed testing method of the electric arc heater of the present invention under case b.

[0065] Figure 5c is a schematic diagram of the arc spot position predicted by the arc spot position and rotation speed test method of the present invention under case c.

[0066] In the diagram: 1. High-speed camera; 2. Observation glass; 3. Thermocouple wire outlet; 4. Thermocouple connection wire; 5. Wireless signal collector; 6. Thermocouple at the left end; 7. Thermocouple at the right end; 8. Electric arc; 9. Anode; 10. Insulating ring; 11. Magnetic field coil; 12. Cathode; 13. Screw. Detailed Implementation

[0067] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Example

[0068] In this embodiment, an M4 screw 13 is used. The screw 13 is 5mm long, the thermocouple is 1mm in diameter, and the thermocouple extends 1mm beyond the screw 13.

[0069] The heater arc spot position and rotation speed testing method in this embodiment adopts, as follows: Figure 1 , Figure 2 , Figure 3The arc heater arc spot position and rotation speed testing device shown includes a cathode 12, an insulating ring 10 and an anode 9 connected in sequence from front to back. A housing is fitted over the cathode 12, the insulating ring 10 and the anode 9. A cooling pipe is provided between the cathode 12, the insulating ring 10 and the anode 9 and the housing.

[0070] An observation glass 2 is installed inside the end face on the left side of the outer casing, and a high-speed camera 1 is positioned to take pictures of the observation glass 2. A wireless signal collector 5 is installed on the outer wall of the left side of the outer casing, and a magnetic field coil 11 is installed on the outer wall of the middle section of the outer casing.

[0071] Several heat transfer ribs are evenly distributed circumferentially on the tube wall of cathode 12. Several thermocouples are installed at equal intervals from front to back on one of the heat transfer ribs A. The starting thermocouple is the left thermocouple 6, and the ending thermocouple is the right thermocouple 7. The left thermocouple 6 is located to the left of magnetic field coil 11, and the right thermocouple 7 is located to the right of magnetic field coil 11. The thermocouple connecting wires 4 of each thermocouple converge into a single strand and are led out from the thermocouple wire outlet 3 located on the left side of the outer shell through a cooling pipe, and connected to the wireless signal collector 5.

[0072] The method includes the following steps:

[0073] S10. Establish signal acquisition and transmission channels;

[0074] like Figure 4 As shown, the thermocouple connection wire 4 of the thermocouple is connected to the signal isolator, the signal isolator is connected to the wireless signal acquisition device 5, the wireless signal acquisition device 5 is wirelessly connected to the wireless AP in the test hall, and the wireless AP is connected to the industrial control computer.

[0075] S20. Start the test, generating an electric arc 8;

[0076] When the equipment is powered on, an electric arc 8 is generated in the cavity that runs through the cathode 12, the insulating ring 10 and the anode 9;

[0077] S30. Data processing;

[0078] S31. Data transmission;

[0079] The wireless signal acquisition device 5 collects the temperature value of the thermocouple, transmits it to the wireless AP in the test hall through the wireless transmitter, and then transmits it to the industrial control computer.

[0080] S32. Determine the axial coordinates of the arc spot;

[0081] Since the temperature at the arc spot location is higher than that at the non-arc spot location, the arc spot location is determined by the fact that the temperature values ​​of two adjacent thermocouples are greater than the temperature values ​​of the remaining thermocouples. The specific steps are as follows:

[0082] Let the axial coordinate of the arc spot be... The highest temperature at the arc root is ;

[0083] Select the three thermocouples with the highest and closest temperatures, with temperatures of respectively , , The corresponding coordinate values ​​are respectively , , ,and < < Because the arc spot area is small and the temperature is high, the temperature at the non-arc spot location drops sharply relative to the arc spot. In order to predict the arc spot location, we assume... The temperature distribution exhibits a linear, triangularly symmetrical pattern; the higher the thermocouple temperature, the closer it is to the arc spot. Let the distance between the two thermocouples be... ;

[0084] Determining the axial coordinates of the arc spot can be divided into the following three cases:

[0085] a. If = Then the axial coordinate of the arc spot is considered to be = ;

[0086] b. If Then it is assumed that the axial coordinate of the arc spot is in and Between, see details Figure 5a ;

[0087] Since the temperature is assumed to be linearly distributed, the thermocouple temperature is inversely proportional to the distance from the arc spot, and the arc spot is related to the coordinate values. x 1 Thermocouple distance at point is d 1 , and coordinate values x 2 Thermocouple distance at point is d 2 Then we have:

[0088] ;

[0089] but:

[0090] ;

[0091] Arc spot axial coordinates Determined as:

[0092] ;

[0093] c. If > > Then it is assumed that the axial coordinate of the arc spot is in and Between, see details Figure 5b ;

[0094] Since the temperature is assumed to be linearly distributed, the thermocouple temperature is inversely proportional to the distance from the arc spot, and the arc spot and... The distance between the thermocouples is ,and The distance between the thermocouples is Then we have:

[0095] ;

[0096] but:

[0097] ;

[0098] Arc spot axial coordinates Determined as:

[0099] .

[0100] Furthermore, the thermocouple is an armored thermocouple with exposed ends and the radial distance between the front end of the thermocouple and the inner wall of the cathode 12 is 2mm to 4mm.

[0101] Furthermore, the thermocouple is welded to the central axis of the screw 13, and the screw 13 is fixed in the screw hole of the heat transfer rib.

[0102] Furthermore, a signal isolator is connected between the thermocouple and the wireless signal acquisition device 5.

[0103] Furthermore, several thermocouples are installed on the heat transfer rib A and the adjacent heat transfer rib B. The thermocouples on heat transfer rib B correspond one-to-one with the thermocouples on heat transfer rib A and have the same axial coordinates. The radial distance between the thermocouples on heat transfer rib A and the inner wall surface of the cathode 12 is... The radial distance between the thermocouple on heat transfer rib B and the inner wall of cathode 12 is , .

[0104] Furthermore, the method also includes the following steps:

[0105] S33. Determine the rotation speed of the arc spot;

[0106] The arc spot rotates along the circumference, causing the temperature values ​​of each thermocouple to change periodically. The rotation speed of the arc spot is calculated based on the rate of periodic change. The magnetic field coil is adjusted in real time according to the rotation speed of the arc spot to reduce the ablation of the electrodes by the arc spot.

[0107] S34. Calculate the heat flux value of arc spot heating;

[0108] Using the thermocouples on heat transfer fin A and the adjacent heat transfer fin B, calculate the heat flux value for arc spot heating. q :

[0109] ;

[0110] in, The temperature value of the thermocouple on heat transfer fin A; The temperature value of the thermocouple on heat transfer rib B, which is at the same axial position as the thermocouple on heat transfer rib A. λ The thermal conductivity of cathode 12 material;

[0111] S35. Capture moving images of the arc spot;

[0112] High-speed camera 1 captures motion images of the arc spot by observing glass 2.

[0113] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. For those skilled in the art, all features disclosed in this invention, or steps in all disclosed methods or processes, except for mutually exclusive features and / or steps, can be combined in any way without departing from the principles of the invention. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and examples shown and described herein.

Claims

1. A method for testing the arc spot position and rotation speed of an electric arc heater, characterized in that, The method uses an arc heater arc spot position and rotation speed testing device, which includes a cathode (12), an insulating ring (10) and an anode (9) connected in sequence from front to back. A housing is fitted over the cathode (12), the insulating ring (10) and the anode (9), and a cooling pipe is provided between the cathode (12), the insulating ring (10) and the anode (9) and the housing. An observation glass (2) is installed inside the end face of the left end of the outer shell, and a high-speed camera (1) is positioned to take pictures of the observation glass (2); a wireless signal collector (5) is set on the outer wall of the left side of the outer shell, and a magnetic field coil (11) is set on the outer wall of the middle section of the outer shell. Several heat transfer ribs are evenly distributed along the circumference of the tube wall of the cathode (12). Several thermocouples are installed at equal intervals from front to back on one of the heat transfer ribs A. The starting thermocouple is the left thermocouple (6) and the ending thermocouple is the right thermocouple (7). The left thermocouple (6) is located to the left of the magnetic field coil (11) and the right thermocouple (7) is located to the right of the magnetic field coil (11). The thermocouple connecting wires (4) of each thermocouple converge into a single strand and are led out from the thermocouple wire outlet (3) located on the left side of the outer shell through the cooling pipe and connected to the wireless signal collector (5). The method includes the following steps: S10. Establish signal acquisition and transmission channels; Connect the thermocouple connecting wire (4) of the thermocouple to the signal isolator, connect the signal isolator to the wireless signal acquisition device (5), connect the wireless signal acquisition device (5) to the wireless AP in the test hall, and connect the wireless AP to the industrial control computer. S20. Start the test and generate an electric arc (8); When the device is powered on, an electric arc (8) is generated in the cavity that runs through the cathode (12), the insulating ring (10), and the anode (9). S30. Data processing; S31. Data transmission; The wireless signal acquisition device (5) collects the temperature value of the thermocouple, transmits it to the wireless AP in the test hall through the wireless transmitter, and then transmits it to the industrial control computer. S32. Determine the axial coordinates of the arc spot; Since the temperature at the arc spot location is higher than that at the non-arc spot location, the arc spot location is determined by the fact that the temperature values ​​of two adjacent thermocouples are greater than the temperature values ​​of the remaining thermocouples. The specific steps are as follows: Let the axial coordinate of the arc spot be... The highest temperature at the arc root is ; Select the three thermocouples with the highest and closest temperatures, with temperatures of respectively , , The corresponding coordinate values ​​are respectively , , ,and < < Because the arc spot area is small and the temperature is high, the temperature at the non-arc spot location drops sharply relative to the arc spot. In order to predict the arc spot location, we assume... The temperature distribution exhibits a linear, triangularly symmetrical pattern; the higher the thermocouple temperature, the closer it is to the arc spot. Let the distance between the two thermocouples be... ; Determining the axial coordinates of the arc spot can be divided into the following three cases: a. If = Then the axial coordinate of the arc spot is considered to be = ; b. If Then it is assumed that the axial coordinate of the arc spot is in and between; Since the temperature is assumed to be linearly distributed, the thermocouple temperature is inversely proportional to the distance from the arc spot, and the arc spot is related to the coordinate values. x 1 Thermocouple distance at point is d 1 , and coordinate values x 2 Thermocouple distance at point is d 2 Then we have: ； but: ； Arc spot axial coordinates Determined as: ； c. If > > Then it is assumed that the axial coordinate of the arc spot is in and between; Since the temperature is assumed to be linearly distributed, the thermocouple temperature is inversely proportional to the distance from the arc spot, and the arc spot and... The distance between the thermocouples is ,and The distance between the thermocouples is Then we have: ； but: ； Arc spot axial coordinates Determined as: 。 2. The method for testing the arc spot position and rotation speed of an arc heater according to claim 1, characterized in that, The thermocouple is a sheathed thermocouple with exposed wires. The radial distance between the front end of the wire and the inner wall of the cathode (12) is 2mm to 4mm.

3. The method for testing the arc spot position and rotation speed of an arc heater according to claim 1, characterized in that, The thermocouple is welded to the central axis of the screw (13), and the screw (13) is fixed in the screw hole of the heat transfer rib.

4. The method for testing the arc spot position and rotation speed of an arc heater according to claim 1, characterized in that, A signal isolator is connected between the thermocouple and the wireless signal acquisition device (5).

5. The method for testing the arc spot position and rotation speed of an electric arc heater according to claim 1, characterized in that, Several thermocouples are installed on the heat transfer rib A and the adjacent heat transfer rib B. The thermocouples on heat transfer rib B correspond one-to-one with the thermocouples on heat transfer rib A and have the same axial coordinates. The radial distance between the thermocouples on heat transfer rib A and the inner wall of the cathode (12) is... The radial distance between the thermocouple on heat transfer rib B and the inner wall of the cathode (12) is , .

6. The method for testing the arc spot position and rotation speed of an arc heater according to claim 1, characterized in that, The method also includes the following steps: S33. Determine the rotation speed of the arc spot; The arc spot rotates along the circumference, causing the temperature values ​​of each thermocouple to change periodically. The rotation speed of the arc spot is calculated based on the rate of periodic change. The magnetic field coil is adjusted in real time according to the rotation speed of the arc spot to reduce the ablation of the electrodes by the arc spot. S34. Calculate the heat flux value of arc spot heating; Using the thermocouples on heat transfer fin A and the adjacent heat transfer fin B, calculate the heat flux value for arc spot heating. q : ； in, The temperature value of the thermocouple on heat transfer fin A; The temperature value of the thermocouple on heat transfer rib B, which is at the same axial position as the thermocouple on heat transfer rib A. λ The thermal conductivity of the cathode (12) material; S35. Capture moving images of the arc spot; A high-speed camera (1) captures motion images of the arc spot by observing the glass (2).

Images