Three-phase ac arc heater flow field low nox control device

Abstract

The application discloses a three-phase alternating current arc heater flow field low NOx control device, which comprises a three-phase alternating current arc wind tunnel system, a total air temperature control system and a NOx concentration control system; wherein the three-phase alternating current arc wind tunnel system is connected with the total air temperature control system and the NOx concentration control system respectively; and the NOx concentration control system is connected with the total air temperature control system. The application realizes accurate control of the NOx concentration of the flow field, improves the flow field quality of the arc heater in the aerodynamic force test, and reduces the adverse effect of the NOx component on the test.

Description

Technical Field

[0001] This invention belongs to the technical field of AC arc heaters, and particularly relates to a low NOx control device for the flow field of a three-phase AC arc heater. Background Technology

[0002] In the field of aerospace aerothermal technology, AC arc heaters are an important type of heater. They use industrial frequency AC power to generate an AC arc to heat the airflow, thereby providing a high enthalpy and high pressure airflow. They play an important role in material ablation heat protection and structural thermal sealing.

[0003] As the Mach number of airflow in conventional hypersonic wind tunnels continues to increase, traditional methods such as kerosene heating and heat storage plate heating are no longer sufficient to meet the heating requirements for large-volume gases. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and provide a low NOx control device for the flow field of a three-phase AC arc heater, which realizes precise control of NOx concentration in the flow field, improves the flow field quality of the arc heater in aerodynamic tests, and reduces the adverse effects of NOx components on the test.

[0005] The objective of this invention is achieved through the following technical solution: a low NOx control device for the flow field of a three-phase AC arc heater, comprising: a three-phase AC arc wind tunnel system, an airflow total temperature control system, and a NOx concentration control system; wherein, the three-phase AC arc wind tunnel system is connected to the airflow total temperature control system and the NOx concentration control system respectively; the NOx concentration control system and the airflow total temperature control system are connected.

[0006] In the aforementioned three-phase AC arc heater flow field low NOx control device, the three-phase AC arc wind tunnel system is used to generate a nitrogen-oxygen mixed airflow; the airflow total temperature control system monitors the temperature of the nitrogen-oxygen mixed airflow in real time and adjusts the ratio of primary nitrogen to secondary nitrogen to ensure that the temperature of the nitrogen-oxygen mixed airflow is not higher than the reaction temperature of nitrogen oxides; the NOx concentration control system monitors the NOx concentration of the airflow at the nozzle outlet inside the arc wind tunnel of the three-phase AC arc wind tunnel system in real time.

[0007] In the aforementioned three-phase AC arc heater flow field low NOx control device, the three-phase AC arc wind tunnel system includes a three-phase AC arc heater, a gas supply device, an AC power supply, a water supply device, an arc wind tunnel, and a vacuum system; wherein, the three-phase AC arc heater is connected to the gas supply device, the AC power supply, the water supply device, and the arc wind tunnel respectively; the arc wind tunnel is connected to the vacuum system.

[0008] In the above-mentioned three-phase AC arc heater flow field low NOx control device, the three-phase AC arc heater includes a heater arm inlet ring, a nitrogen inlet chamber, and an oxygen inlet chamber; wherein, the heater arm inlet ring, the nitrogen inlet chamber, and the oxygen inlet chamber are connected in sequence; the oxygen inlet chamber is connected to the arc wind tunnel; and the gas supply device is connected to the heater arm inlet ring, the nitrogen inlet chamber, and the oxygen inlet chamber respectively.

[0009] In the aforementioned three-phase AC arc heater flow field low NOx control device, the power supply provides the three-phase AC arc heater with high-voltage AC power at industrial frequency; the water supply device provides the three-phase AC arc heater with high-pressure cooling water; the primary nitrogen supplied by the gas supply device enters the heater arm inlet ring, the secondary nitrogen supplied by the gas supply device enters the nitrogen inlet chamber, and the oxygen supplied by the gas supply device enters the oxygen inlet chamber; the heater heats the primary nitrogen entering the heater arm inlet ring, and the heated primary nitrogen enters the nitrogen inlet chamber; the secondary nitrogen mixes with the heated primary nitrogen to obtain nitrogen in a lower temperature molecular state, and the lower temperature molecular state nitrogen enters the oxygen inlet chamber; the lower temperature molecular state nitrogen mixes with oxygen to obtain a nitrogen-oxygen mixed gas flow, and the nitrogen-oxygen mixed gas flow enters the vacuum system through the arc wind tunnel.

[0010] In the aforementioned three-phase AC arc heater flow field low NOx control device, the total airflow temperature control system includes a temperature acquisition unit, a temperature signal processor, a central control system, and a gas supply controller. The temperature acquisition unit collects the temperature signal of the nitrogen-oxygen mixed airflow in real time and inputs it into the temperature signal processor. The temperature signal processor receives the nitrogen-oxygen mixed airflow temperature signal, processes it to obtain a processed temperature signal, and transmits the processed temperature signal to the central control system. The central control system, when detecting that the processed temperature signal is higher than the reaction temperature for NOx generation, issues a command signal to the gas supply controller. The gas supply controller receives the command signal and, based on the command signal, controls the gas supply device to adjust the ratio of primary to secondary nitrogen to ensure that the temperature of the nitrogen-oxygen mixed airflow is never higher than the reaction temperature for NOx generation.

[0011] In the above-mentioned three-phase AC arc heater flow field low NOx control device, the NOx concentration control system includes an absorption spectroscopy system; wherein, the absorption spectroscopy system emits a measuring laser, which passes through the nitrogen-oxygen mixed gas flow to obtain the NOx concentration in the nitrogen-oxygen mixed gas flow.

[0012] In the aforementioned three-phase AC arc heater flow field low NOx control device, the absorption spectroscopy system includes a signal generator, a laser controller, a laser generator, a photodetector, and a photoelectric signal processor. The signal generator sends a signal to the laser controller. The laser controller receives the signal and, upon receiving it, controls the laser generator to emit a measuring laser that passes through the nitrogen-oxygen mixed gas flow within the arc wind tunnel. The photodetector collects the nitrogen-oxygen mixed gas flow and transmits it to the photoelectric signal processor. The photoelectric signal processor obtains the NOx concentration in the nitrogen-oxygen mixed gas flow based on the NOx concentration and transmits this concentration to the central control system.

[0013] In the aforementioned three-phase AC arc heater flow field low NOx control device, the central control system: determines the magnitude of the NOx concentration in the nitrogen-oxygen mixed gas flow and the concentration value required for the aerodynamic test flow field; if the NOx concentration in the nitrogen-oxygen mixed gas flow is higher than the concentration value required for the aerodynamic test flow field, it issues a second command signal to the gas supply controller.

[0014] In the above-mentioned three-phase AC arc heater flow field low NOx control device, the gas supply controller receives a second command signal and controls the gas supply device to adjust the ratio of primary nitrogen to secondary nitrogen according to the second command signal, thereby achieving a preset value for the NOx concentration in the flow field.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] (1) In this invention, the total airflow temperature control system monitors the temperature of the nitrogen-oxygen mixed airflow in real time and adjusts the ratio of primary nitrogen to secondary nitrogen to ensure that the temperature of the nitrogen-oxygen mixed airflow is not higher than the reaction temperature of nitrogen oxides (NOx). The phased entry of primary nitrogen, secondary nitrogen and oxygen not only effectively reduces the generation of nitrogen oxides (NOx), but also simulates the airflow composition of conventional hypersonic wind tunnels, avoiding the interference of electric arc heating on the aerodynamic flow field.

[0017] (2) In this invention, the NOx concentration control system monitors the NOx concentration of the airflow at the nozzle outlet in the arc wind tunnel in real time through an absorption spectroscopy system, and further adjusts the ratio of primary nitrogen to secondary nitrogen. The two-stage regulation of the airflow total temperature control system and the NOx concentration control system achieves precise control of the NOx concentration in the flow field, improves the flow field quality of the arc heater in the aerodynamic test, and reduces the adverse effects of NOx components on the test. Attached Figure Description

[0018] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0019] Figure 1 This is a structural diagram of the low NOx control device for the flow field of a three-phase AC arc heater provided in an embodiment of the present invention;

[0020] Figure 2 This is a diagram of the three-phase AC arc wind tunnel system provided in an embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the air inlet position of the three-phase AC arc heater provided in an embodiment of the present invention;

[0022] Figure 4 This is a diagram illustrating the composition of the airflow total temperature control system provided in an embodiment of the present invention;

[0023] Figure 5 This is a diagram illustrating the composition of the NOx concentration control system provided in an embodiment of the present invention.

[0024] Figure 6 This is a diagram of the absorption spectroscopy system provided in an embodiment of the present invention. Detailed Implementation

[0025] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0026] Figure 1 This is a structural diagram of the low NOx control device for the flow field of a three-phase AC arc heater provided in an embodiment of the present invention. Figure 1 As shown, the three-phase AC arc heater flow field low NOx control device includes: a three-phase AC arc wind tunnel system, an airflow total temperature control system, and a NOx concentration control system; wherein, the three-phase AC arc wind tunnel system is connected to the airflow total temperature control system and the NOx concentration control system respectively; the NOx concentration control system and the airflow total temperature control system are connected.

[0027] The three-phase AC arc wind tunnel system is used to generate a nitrogen-oxygen mixed airflow; the total airflow temperature control system monitors the temperature of the nitrogen-oxygen mixed airflow in real time and adjusts the ratio of primary nitrogen to secondary nitrogen to ensure that the temperature of the nitrogen-oxygen mixed airflow does not exceed the reaction temperature of nitrogen oxides; the NOx concentration control system monitors the NOx concentration of the airflow at the nozzle outlet inside the arc wind tunnel of the three-phase AC arc wind tunnel system in real time.

[0028] The AC arc heater heats the primary nitrogen gas entering through the three heater arm intake rings. Secondary nitrogen gas enters through the nitrogen intake chamber and mixes with the primary nitrogen gas. Oxygen enters through the oxygen intake chamber and mixes with the incoming nitrogen gas again. The mass ratio of oxygen to nitrogen gas is strictly controlled according to the air composition.

[0029] The airflow total temperature control system monitors the temperature of the nitrogen-oxygen mixed airflow in real time and adjusts the ratio of primary nitrogen to secondary nitrogen to ensure that the temperature of the nitrogen-oxygen mixed airflow does not exceed the reaction temperature at which nitrogen oxides (NOx) are generated.

[0030] The NOx concentration control system monitors the NOx concentration of the airflow at the nozzle outlet in the arc wind tunnel in real time through an absorption spectroscopy system, and further adjusts the ratio of primary nitrogen to secondary nitrogen to achieve quantitative control of the NOx concentration in the flow field.

[0031] The two-stage regulation of the airflow total temperature control system and the NOx concentration control system enables precise control of the NOx concentration in the flow field, improves the flow field quality of the electric arc heater in the aerodynamic test, and reduces the adverse effects of NOx components on the test.

[0032] The phased introduction of primary nitrogen, secondary nitrogen, and oxygen effectively reduces the generation of nitrogen oxides (NOx) while simulating the airflow composition of a conventional hypersonic wind tunnel, thus avoiding interference to the aerodynamic flow field caused by electric arc heating.

[0033] like Figure 2 As shown, the three-phase AC arc wind tunnel system includes a three-phase AC arc heater 11, an air supply device 12, an AC power supply 13, a water supply device 14, an arc wind tunnel 15, and a vacuum system 16; wherein, the three-phase AC arc heater 11 is connected to the air supply device 12, the AC power supply 13, the water supply device 14, and the arc wind tunnel 15 respectively; the arc wind tunnel 15 is connected to the vacuum system 16.

[0034] like Figure 3As shown, the three-phase AC arc heater 11 includes a heater arm air inlet ring 111, a nitrogen air inlet chamber 112, and an oxygen air inlet chamber 113; wherein, the heater arm air inlet ring 111, the nitrogen air inlet chamber 112, and the oxygen air inlet chamber 113 are connected in sequence; the oxygen air inlet chamber 113 is connected to the arc wind tunnel 15; and the gas supply device 12 is connected to the heater arm air inlet ring 111, the nitrogen air inlet chamber 112, and the oxygen air inlet chamber 113 respectively.

[0035] Power supply 13 provides high-voltage AC power at industrial frequency to the three-phase AC arc heater 11; water supply device 14 provides high-pressure cooling water to the three-phase AC arc heater 11; primary nitrogen supplied by gas supply device 12 enters the heater arm air inlet ring 111, secondary nitrogen supplied by gas supply device 12 enters the nitrogen inlet chamber 112, and oxygen supplied by gas supply device 12 enters the oxygen inlet chamber 113; the heater heats the primary nitrogen entering the heater arm air inlet ring 111, and the heated primary nitrogen enters the nitrogen inlet chamber 112; the secondary nitrogen mixes with the heated primary nitrogen to obtain nitrogen in a lower temperature molecular state, and the nitrogen in the lower temperature molecular state enters the oxygen inlet chamber 113; the nitrogen in the lower temperature molecular state mixes with oxygen to obtain a nitrogen-oxygen mixed gas flow, and the nitrogen-oxygen mixed gas flow enters the vacuum system 16 through the arc wind tunnel 15.

[0036] like Figure 4 As shown, the airflow total temperature control system includes a temperature acquisition unit 21, a temperature signal processor 22, a central control system 23, and a gas supply controller 24. The temperature acquisition unit 21 acquires the temperature signal of the nitrogen-oxygen mixed airflow in real time and inputs it into the temperature signal processor 22. The temperature signal processor 22 receives the nitrogen-oxygen mixed airflow temperature signal, processes it to obtain a processed temperature signal, and transmits the processed temperature signal to the central control system 23. The central control system 23, when detecting that the processed temperature signal is higher than the reaction temperature of nitrogen oxides, sends a command signal to the gas supply controller 24. The gas supply controller 24 receives the command signal and, according to the command signal, controls the gas supply device 12 to adjust the ratio of primary nitrogen to secondary nitrogen to ensure that the temperature of the nitrogen-oxygen mixed airflow is never higher than the reaction temperature of NOx production.

[0037] like Figure 5 As shown, the NOx concentration control system includes an absorption spectroscopy system 31; wherein, the absorption spectroscopy system 31 emits a measuring laser, which passes through the nitrogen-oxygen mixed gas flow to obtain the NOx concentration in the nitrogen-oxygen mixed gas flow.

[0038] like Figure 6As shown, the absorption spectroscopy system 31 includes a signal generator 311, a laser controller 312, a laser generator 313, a photodetector 314, and a photoelectric signal processor 315. The signal generator 311 sends a signal to the laser controller 312. The laser controller 312 receives the signal and, upon receiving it, controls the laser generator 313 to emit a measuring laser that passes through the nitrogen-oxygen mixed gas flow within the arc wind tunnel 15. The photodetector 314 collects the nitrogen-oxygen mixed gas flow and transmits it to the photoelectric signal processor 315. The photoelectric signal processor 315 obtains the NOx concentration in the nitrogen-oxygen mixed gas flow based on the NOx concentration and transmits this concentration to the central control system 23. The central control system 23 determines whether the NOx concentration in the nitrogen-oxygen mixed gas flow is higher than the required concentration value for the aerodynamic test flow field. If the NOx concentration in the nitrogen-oxygen mixed gas flow is higher than the required concentration value for the aerodynamic test flow field, it sends a second command signal to the gas supply controller 24. Gas supply controller 24: Receives the second command signal and controls the gas supply device 12 to adjust the ratio of primary nitrogen to secondary nitrogen according to the second command signal, so as to achieve the preset value of NOx concentration in the flow field.

[0039] With the gas supply device 12 providing high-pressure gas, the AC power supply 13 providing high-voltage AC power, and the water supply device 14 providing high-pressure cooling water, the three-phase AC arc heater 11 heats the primary nitrogen entering through the three heater arm inlet rings 111. The heated nitrogen is in a high-temperature plasma state. Secondary nitrogen enters through the nitrogen inlet chamber 112 and mixes with the high-temperature primary nitrogen. The gas flow temperature drops rapidly, and the nitrogen plasma recombines into a molecular state. Oxygen enters through the oxygen inlet chamber 113 and mixes with the lower-temperature molecular state nitrogen. The mass ratio of oxygen to nitrogen is strictly controlled according to the air composition. The supersonic gas flow formed by the nitrogen-oxygen mixture passes through the arc wind tunnel 15 and finally enters the vacuum system 16.

[0040] The airflow total temperature control system 2 collects the temperature signal of the nitrogen-oxygen mixed airflow in real time through the temperature acquisition device 21, and inputs the collected temperature signal into the temperature signal processor 22. The processed temperature signal enters the central control system 23. When the measured nitrogen-oxygen mixed airflow is higher than the reaction temperature of nitrogen oxides (NOx), a signal is sent to the gas supply controller 24, which then controls the gas supply device to adjust the ratio of primary nitrogen to secondary nitrogen to ensure that the temperature of the nitrogen-oxygen mixed airflow is always not higher than the reaction temperature of NOx.

[0041] The NOx concentration control system 3 sends a signal through the signal generator 311 in the absorption spectroscopy system 31. Upon receiving the signal, the laser controller 312 controls the laser generator 313 to emit a measuring laser. This laser passes through the nitrogen-oxygen supersonic airflow in the arc wind tunnel 15, is collected by the photodetector 314, and processed by the photoelectric signal processor 315. The signal is then sent to the central control system to obtain the NOx concentration in the nitrogen-oxygen supersonic airflow. If the NOx concentration is higher than the concentration required for the aerodynamic test flow field, the central control system sends a signal to the gas supply control device, which then further adjusts the ratio of primary to secondary nitrogen intake, thereby achieving quantitative control of the NOx concentration in the flow field.

[0042] The two-stage control system of total airflow temperature control (2) and NOx concentration control system (3) enables precise control of NOx concentration in the flow field, improving the flow field quality of the arc heater in aerodynamic experiments and reducing the adverse effects of NOx components on the experiment. The staged introduction of primary nitrogen, secondary nitrogen, and oxygen effectively reduces the generation of nitrogen oxides (NOx) while simulating the airflow composition of a conventional hypersonic wind tunnel, avoiding interference to the aerodynamic flow field caused by arc heating.

[0043] In this embodiment, the total airflow temperature control system monitors the temperature of the nitrogen-oxygen mixed airflow in real time and adjusts the ratio of primary to secondary nitrogen to ensure that the temperature of the nitrogen-oxygen mixed airflow does not exceed the reaction temperature for the generation of nitrogen oxides (NOx). The phased introduction of primary nitrogen, secondary nitrogen, and oxygen effectively reduces the generation of NOx while simulating the airflow composition of a conventional hypersonic wind tunnel, avoiding interference from the electric arc heating method on the aerodynamic flow field. In this embodiment, the NOx concentration control system monitors the NOx concentration of the airflow at the nozzle exit in real time using an absorption spectroscopy system and further adjusts the ratio of primary to secondary nitrogen. The two-stage regulation of the total airflow temperature control system and the NOx concentration control system achieves precise control of the NOx concentration in the flow field, improves the flow field quality of the electric arc heater in the aerodynamic experiment, and reduces the adverse effects of NOx components on the experiment.

[0044] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. A low NOx control device for the flow field of a three-phase AC arc heater, characterized in that... include: The system includes a three-phase AC arc wind tunnel system, an airflow total temperature control system, and a NOx concentration control system; among which... The three-phase AC arc wind tunnel system is connected to the airflow total temperature control system and the NOx concentration control system, respectively; The NOx concentration control system and the airflow total temperature control system are connected; The three-phase AC arc wind tunnel system includes a three-phase AC arc heater (11), a gas supply device (12), an AC power supply (13), a water supply device (14), an arc wind tunnel (15), and a vacuum system (16); wherein, The three-phase AC arc heater (11) is connected to the gas supply device (12), the AC power supply (13), the water supply device (14), and the arc wind tunnel (15), respectively. The electric arc wind tunnel (15) and the vacuum system (16) are connected; The three-phase AC arc heater (11) includes a heater arm inlet ring (111), a nitrogen inlet chamber (112), and an oxygen inlet chamber (113); wherein, The heater arm air inlet ring (111), the nitrogen air inlet chamber (112), and the oxygen air inlet chamber (113) are connected in sequence; The oxygen intake chamber (113) is connected to the electric arc wind tunnel (15); The gas supply device (12) is connected to the heater arm air inlet ring (111), the nitrogen inlet chamber (112) and the oxygen inlet chamber (113) respectively; The power supply (13) provides the three-phase AC arc heater (11) with high-voltage AC power at the power frequency; The water supply device (14) provides high-pressure cooling water to the three-phase AC arc heater (11); The primary nitrogen supplied by the gas supply device (12) enters the heater arm air inlet ring (111), the secondary nitrogen supplied by the gas supply device (12) enters the nitrogen inlet chamber (112), and the oxygen supplied by the gas supply device (12) enters the oxygen inlet chamber (113). The heater heats the primary nitrogen gas entering through the heater arm inlet ring (111). The heated primary nitrogen gas enters the nitrogen inlet chamber (112). The secondary nitrogen gas is mixed with the heated primary nitrogen gas to obtain nitrogen gas in a lower temperature molecular state. The nitrogen gas in the lower temperature molecular state enters the oxygen inlet chamber (113). The nitrogen gas in the lower temperature molecular state is mixed with oxygen to obtain a nitrogen-oxygen mixed gas flow. The nitrogen-oxygen mixed gas flow enters the vacuum system (16) through the electric arc wind tunnel (15).

2. The low NOx control device for the flow field of a three-phase AC arc heater according to claim 1, characterized in that: The three-phase AC arc wind tunnel system is used to generate a nitrogen-oxygen mixed airflow. The airflow total temperature control system monitors the temperature of the nitrogen-oxygen mixed airflow in real time and adjusts the ratio of primary nitrogen to secondary nitrogen to ensure that the temperature of the nitrogen-oxygen mixed airflow does not exceed the reaction temperature of nitrogen oxides. The NOx concentration control system monitors the NOx concentration of the airflow at the nozzle outlet in the arc wind tunnel of the three-phase AC arc wind tunnel system in real time.

3. The low NOx control device for the flow field of a three-phase AC arc heater according to claim 1, characterized in that: The airflow total temperature control system includes a temperature acquisition unit (21), a temperature signal processor (22), a central control system (23), and an air supply controller (24); wherein, The temperature acquisition device (21) acquires the temperature signal of the nitrogen-oxygen mixed gas flow in real time and inputs the temperature signal of the nitrogen-oxygen mixed gas flow into the temperature signal processor (22). The temperature signal processor (22) receives the temperature signal of the nitrogen-oxygen mixed gas flow, processes the temperature signal of the nitrogen-oxygen mixed gas flow to obtain the processed temperature signal, and transmits the processed temperature signal to the central control system (23). The central control system (23): when the processed temperature signal is detected to be higher than the reaction temperature of nitrogen oxides, it sends a command signal to the gas supply controller (24). The gas supply controller (24) receives the command signal and controls the gas supply device (12) to adjust the ratio of primary nitrogen to secondary nitrogen according to the command signal, so as to ensure that the temperature of the nitrogen-oxygen mixed gas flow is always not higher than the reaction temperature of NOx generation.

4. The low NOx control device for the flow field of a three-phase AC arc heater according to claim 3, characterized in that: The NOx concentration control system includes an absorption spectroscopy system (31); wherein... The absorption spectroscopy system (31) emits a measurement laser, which passes through the nitrogen-oxygen mixed gas flow to obtain the NOx concentration in the nitrogen-oxygen mixed gas flow.

5. The low NOx control device for the flow field of a three-phase AC arc heater according to claim 4, characterized in that: The absorption spectroscopy system (31) includes a signal generator (311), a laser controller (312), a laser generator (313), a photodetector (314), and a photoelectric signal processor (315); wherein, The signal generator (311) sends a signal to the laser controller (312). The laser controller (312) receives a signal and controls the laser generator (313) to emit a measuring laser that passes through the nitrogen-oxygen mixed airflow inside the electric arc wind tunnel (15). The photodetector (314) collects the nitrogen-oxygen mixed gas flow and transmits it to the photodetector (315). The photoelectric signal processor (315) obtains the NOx concentration in the nitrogen-oxygen mixed gas flow based on the nitrogen-oxygen mixed gas flow and transmits the NOx concentration in the nitrogen-oxygen mixed gas flow to the central control system (23).

6. The low NOx control device for the flow field of a three-phase AC arc heater according to claim 5, characterized in that: The central control system (23) determines the NOx concentration in the nitrogen-oxygen mixed gas flow and the concentration value required for the aerodynamic test flow field. If the NOx concentration in the nitrogen-oxygen mixed gas flow is higher than the concentration value required for the aerodynamic test flow field, it sends a second command signal to the gas supply controller (24).

7. The low NOx control device for the flow field of a three-phase AC arc heater according to claim 6, characterized in that: The gas supply controller (24) receives the second command signal and controls the gas supply device (12) to adjust the ratio of primary nitrogen to secondary nitrogen according to the second command signal, so as to achieve the NOx concentration in the flow field reaching the preset value.

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