Hypersonic Wind Tunnel Heater System Based on Supercapacitor and Its Control Method

Abstract

The present application discloses a hypersonic wind tunnel heater system based on supercapacitors and its control method. The system includes a heater, and the heater includes: a supercapacitor battery pack for providing electrical energy; a power regulator circuit-connected to the supercapacitor battery pack for stable output of electrical energy during the heating process and capable of voltage control according to the control logic; and electrothermal materials circuit-connected to the power regulator for converting the stable electrical energy output by the power regulator into heat energy to exchange heat with the airflow flowing into the heater. The present application has the characteristics of large instantaneous discharge power and a large number of charge-discharge cycle life times. Using the supercapacitor battery pack as the power supply system for the direct-heating heater of the hypersonic wind tunnel, it solves the problems of the heater power supply system and can achieve direct-heating power supply for the transient high-power heater. The present application has a relatively low cost and does not require a complex power supply and distribution system, etc., and can efficiently achieve the control of the outlet temperature of the direct-heating heater.

Description

Technical Field

[0001] This application relates to the technical field of hypersonic wind tunnels, and particularly to a hypersonic wind tunnel heater system based on super capacitors and a control method thereof. Background Art

[0002] Conventional hypersonic wind tunnels mainly consist of a high-pressure gas source, a settling chamber, a nozzle, a test section, and a vacuum system, etc. When the wind tunnel operates, high-pressure gas expands and accelerates through the nozzle to the test section, and a hypersonic airflow is established in the test section. For hypersonic wind tunnels, due to the relatively high Mach number, the temperature decreases during the process of airflow expansion and acceleration. At this time, not only water vapor and carbon dioxide will condense, but also the air components themselves may condense. To avoid gas supersaturation and condensation, various heaters need to be added to heat the gas so that the wind tunnel can operate under non-condensing conditions.

[0003] Currently, the widely used heaters are divided into two types according to different heating methods: direct heating type and regenerative heating type. The regenerative heater needs to preheat the regenerative element in advance, and then the regenerative element heats the test airflow. According to different preheating methods, it is divided into three types: electric preheating, gas preheating, and fuel preheating. The regenerator generally uses porous laminates, corundum ceramic balls, etc. Before the wind tunnel operates, the regenerator needs to be preheated in advance, and the heating time is relatively long, usually in the order of hours. At the same time, since the heat is stored in the regenerator, the insulation requirement for the heater is higher to prevent the stored heat from dissipating.

[0004] The direct heating type heater does not need to store heat in advance, can realize instant heating of air, directly heats the test airflow, and almost does not require preheating time. And because the air directly exchanges heat with the electrothermal material, the requirement for the heater's heat preservation and insulation is reduced a lot. The heating methods of the direct heating type heater are also divided into three types: electrothermal type, gas type, and fuel type. The electrothermal type is divided into belt type, wire type, and tube type according to the different shapes of the resistance elements.

[0005] Generally speaking, among the above heating methods, the electric heating method is relatively pure, and other heating methods will always pollute the test airflow. However, the existing direct heating type resistance heater has extremely high power requirements, requires a complex power supply and distribution system and a power regulation system, and it is almost impossible to achieve for units with limited distribution power. It is generally only used for small-sized wind tunnels, and its maximum heating temperature is limited by the maximum temperature that the heating element can withstand. For example, for a hypersonic wind tunnel with an outlet diameter of 0.5m, its typical power supply is above 5MW. Summary of the Invention

[0006] The embodiments of this application provide a hypersonic wind tunnel heater system based on super capacitors to solve the technical problems that the existing direct heating type resistance heater of the wind tunnel has high power requirements for power supply and distribution and is only suitable for small-sized wind tunnels.

[0007] The technical solution adopted in this application is as follows:

[0008] A hypersonic wind tunnel heater system based on supercapacitors, including a heater, the heater comprising:

[0009] A supercapacitor battery pack for providing electrical energy;

[0010] A power regulator, circuit-connected to the supercapacitor battery pack, for stable output of electrical energy during the heating process and voltage control according to the control logic;

[0011] An electrothermal material, circuit-connected to the power regulator, for converting the stable electrical energy output by the power regulator into heat energy and exchanging heat with the airflow flowing into the heater.

[0012] Further, the power of the supercapacitor battery pack is:

[0013] Let the total temperature of the wind tunnel operation be T0, the total pressure be P0, the diameter of the wind tunnel nozzle outlet be D, and the specific heat ratio of air be c p , all in the International System of Units, then the wind tunnel flow rate is:

[0014]

[0015] Without considering heat loss, setting the temperature of the gas at the inlet of the heater system to the normal temperature of 300K, then the required power P of the heater system is:

[0016]

[0017] The required power P is the power of the supercapacitor battery pack.

[0018] Further, the number of supercapacitor modules in the supercapacitor battery pack is calculated according to the discharge time requirement, and the calculation formula is:

[0019] Set the initial voltage of the supercapacitor to U0 (fully charged voltage), the capacitance of the capacitor to C, the power supply power of the heater to P, the power supply voltage to U1, and the total operation time of the wind tunnel to t. For a system using buck DCDC for voltage stabilization control, it is required that the voltage U f > U1. During the operation time, the total energy released by the capacitor is P·t, and the real-time voltage U of the capacitor c , then there is:

[0020]

[0021] It is obtained that:

[0022]

[0023] Also according to the system requirements, Uf > U1

[0024] Then, it can be obtained that:

[0025]

[0026] Furthermore, the basic parameters of the capacitor system can be determined. Considering the long-term operation of the system, the capacitance of the capacitor can be appropriately increased according to the above calculation results.

[0027] Furthermore, the electrothermal material is an electric heating wire or an electric heating tape.

[0028] Furthermore, it further includes a charger for charging the supercapacitor battery pack.

[0029] Furthermore, the charger uses 220V - 380V alternating current.

[0030] Furthermore, it further includes a temperature sensor. The temperature sensor is arranged at the outlet of the heater and is connected to the power regulator circuit. The power regulator uses the temperature at the outlet of the heater collected by the temperature sensor as a control parameter to perform feedback control on the output power.

[0031] On the other hand, this application also provides a control method for a hypersonic wind tunnel heater system based on the supercapacitor as described above, including the steps of:

[0032] Prepare the high-pressure and vacuum systems of the wind tunnel for operation. The high-pressure gas tank stores high-pressure gas, and the vacuum chamber is evacuated.

[0033] At time t1 before the wind tunnel runs, when there is no air flow in the heater, electrical energy with an output less than the required power of the wind tunnel is output through the power regulator to preheat and heat the electrothermal material.

[0034] Open the wind tunnel valve. While establishing an air flow in the heater, under the condition of not considering heat loss, the power regulator increases the output power to be equal to the required power of the wind tunnel, and the air flow exchanges heat with the electrothermal material.

[0035] After running for the set time, at time t2 before the valve is closed, turn off the power regulator. At this time, the electrothermal material stops heating, and the air flow continues to carry away the residual heat energy of the electrothermal material to protect the electrothermal material from being burned out.

[0036] Finally, close the valve system of the wind tunnel, and the operation of the wind tunnel ends.

[0037] Furthermore, before the high-pressure and vacuum systems of the wind tunnel are prepared for operation, it further includes the steps of:

[0038] Charge the supercapacitor battery pack through the charger.

[0039] Furthermore, after the operation of the wind tunnel ends, it further includes the steps of:

[0040] Charge the supercapacitor battery pack through a charger to prepare for the next wind tunnel operation.

[0041] Compared with the prior art, the present application has the following beneficial effects:

[0042] The heater of the present application uses a supercapacitor battery pack, a power regulator, and an electric heat exchanger to heat the wind tunnel airflow. The supercapacitor has the characteristics of a large instantaneous discharge power and a large number of charge and discharge cycle life times. Using the supercapacitor battery pack as the power supply system for the direct-heating heater of the hypersonic wind tunnel, the problem of the heater power supply system is solved, and the direct-heating power supply of the transient large-power heater can be realized, effectively solving the problems of ultra-large power supply and power regulation of traditional direct-heating. The cost is relatively low, without the need for a complex power supply and distribution system and power regulation system, and can efficiently realize the control of the outlet temperature of the direct-heating heater. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings:

[0044] Figure 1 is a schematic diagram of the composition principle of a conventional hypersonic wind tunnel.

[0045] Figure 2 is a schematic diagram of the principle of a hypersonic wind tunnel heater system based on supercapacitors according to a preferred embodiment of the present application.

[0046] In the figure: 1, pressure regulating valve; 2, quick valve; 3, nozzle; 4, test section; 5, adjustable supersonic diffuser section; 6, vacuum chamber; 7, cooler; 8, heater; 81, supercapacitor battery pack; 82, power regulator; 83, electrothermal material; 9, high-pressure gas tank; 10, charger. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0048] As Figure 1 shown, a conventional hypersonic wind tunnel mainly consists of a high-pressure gas tank 9, a settling chamber, a nozzle 3, a test section 4, an adjustable supersonic diffuser section 5, a vacuum chamber 6, a cooler 7, and a vacuum chamber 6, etc. The settling chamber includes a pressure regulating valve 1, a heater 8, and a quick valve 2. Among them, limited by the working time of the vacuum and high-pressure systems, the operation time of the existing conventional hypersonic wind tunnel is generally at the level of dozens of seconds to minutes, that is, a transient operation mode. The heater 8 is used to increase the total temperature of the airflow during the operation of the wind tunnel to prevent the gas from condensing during the expansion and acceleration process of the nozzle 3.

[0049] Referring to Figure 2 , a preferred embodiment of the present application provides a hypersonic wind tunnel heater system based on supercapacitors, including a heater 8, where the heater 8 includes a supercapacitor battery pack 81, a power regulator 82, and electrothermal materials 83, and specifically:

[0050] The supercapacitor battery pack 81 is used to provide electrical energy. The supercapacitor battery pack 81 has outstanding advantages such as high power density, rapid charging, long cycle life, wide operating temperature range, long storage life, high reliability, and environmental friendliness. It is particularly suitable for short-time high-power output, properly solving the contradiction between high specific power and high specific energy output of energy storage devices, and can release a large amount of energy in a short time. Due to the working characteristics of the supercapacitor battery pack 81 being consistent with the short-time high-power requirements of the hypersonic wind tunnel, it is very suitable as its energy storage power supply system;

[0051] The power regulator 82 is electrically connected to the supercapacitor battery pack 81 and is used for the stable output of electrical energy during the heating process and can perform voltage control according to the control logic. For a resistive wind tunnel heater, during its operation, the resistance value (i.e., the load) of the electrothermal material 83 basically does not change. However, due to the physical principle of the supercapacitor battery pack 81 itself, as the discharge continues, the output voltage of the supercapacitor battery pack 81 will continuously decrease, resulting in a reduction in the actual power of the heater. Therefore, the supercapacitor battery pack 81 must be used in conjunction with the power regulator 82 to achieve stable voltage output throughout the operation of the heater 8 and achieve constant voltage, constant current, and constant power operation of the power supply system;

[0052] The electrothermal material 83 is electrically connected to the power regulator 82 and is used to convert the stable electrical energy output by the power regulator 82 into heat energy for heat exchange with the airflow flowing into the heater.

[0053] The heater 8 of this embodiment uses a supercapacitor battery pack 81, a power regulator 82, and an electric heat exchanger to heat the wind tunnel airflow. The supercapacitor has the characteristics of a large instantaneous discharge power and a large number of charge-discharge cycle life times. Using the supercapacitor battery pack as the power supply system for the direct-heating heater of the hypersonic wind tunnel solves the problem of the power supply system of the heater 8, enables direct-heating power supply for a temporarily pulsed high-power heater, and effectively solves the problems of ultra-high-power power supply and power regulation of traditional direct-heating. This embodiment has a low cost, does not require a complex power supply and distribution system and power regulation system, and can efficiently achieve the control of the outlet temperature of the direct-heating heater.

[0054] Specifically, the power of the supercapacitor battery pack 81 is:

[0055] Let the total temperature of the wind tunnel operation be T0, the total pressure be P0, the diameter of the wind tunnel nozzle outlet be D, and the specific heat ratio of air be cp , if the above are all in the International System of Units, the wind tunnel flow rate is:

[0056]

[0057] Without considering heat loss, setting the temperature of the gas at the inlet of the heater system to the normal temperature of 300K, the required power P of the heater system is:

[0058]

[0059] The required power P is the power of the supercapacitor battery pack 81.

[0060] Furthermore, the number of supercapacitor modules in the supercapacitor battery pack 81 is calculated according to the discharge time requirement, and the calculation formula is:

[0061] Set the initial voltage of the supercapacitor as U0 (fully charged voltage), the capacitance of the capacitor as C, the power supply power of the heater as P, the supply voltage as U1, and the total operation time of the wind tunnel as t. For a system using a buck DCDC for voltage stabilization control, it is required that the voltage U f >U1. During the operation time, the total energy released by the capacitor is P·t, and the real-time voltage U of the capacitor c , then there is:

[0062]

[0063] It can be obtained that:

[0064]

[0065] Also according to the system requirements, U f >U1

[0066] Then it can be obtained that:

[0067]

[0068] Furthermore, the basic parameters of the capacitor system can be determined. Considering the long-term operation of the system, the capacitance of the capacitor can be appropriately increased according to the above calculation results.

[0069] The above embodiments calculate the power of the supercapacitor battery pack 81 based on the wind tunnel flow rate, operation time, and temperature rise, and calculate the number of supercapacitor modules according to the discharge time requirement, so as to adapt to and meet the heating needs of the hypersonic wind tunnel air flow.

[0070] Preferably, the electrothermal material 83 is an electric heating wire or an electric heating tape.

[0071] Preferably, the hypersonic wind tunnel heater system based on supercapacitors further includes a charger 10 for charging the supercapacitor battery pack 81.

[0072] Preferably, the charger 10 uses 220V - 380V alternating current, and 380V alternating current is used in this embodiment.

[0073] Preferably, the hypersonic wind tunnel heater system based on supercapacitors further includes a temperature sensor. The temperature sensor is arranged at the heater outlet and is circuit-connected to the power regulator 82. The power regulator 82 uses the heater outlet temperature collected by the temperature sensor as a control parameter to perform feedback control on the output power, so as to achieve precise control of the heating temperature.

[0074] Another preferred embodiment of the present application also provides a control method for the hypersonic wind tunnel heater system based on supercapacitors, including the steps of:

[0075] S1. Prepare the high-pressure and vacuum systems of the wind tunnel for operation. The high-pressure gas tank 9 stores high-pressure gas, and the vacuum box 6 is evacuated.

[0076] S2. At time t1 before the wind tunnel runs, there is no air flow in the heater at this time. The power regulator 82 outputs electric energy less than the power required by the wind tunnel to preheat and heat the electrothermal material 83.

[0077] S3. Open the wind tunnel valve. While establishing an air flow in the heater, without considering heat loss, the power regulator 82 increases the output power to be equal to the power required by the wind tunnel, and the air flow exchanges heat with the electrothermal material 83.

[0078] S4. After running for a set time, at time t2 before the valve is closed, turn off the power regulator 82. At this time, the electrothermal material 83 stops heating, and the air flow continues to carry away the residual heat energy of the electrothermal material 82 to protect the electrothermal material 82 from being burned out.

[0079] S5. Finally, close the valve system of the wind tunnel, and the operation of the wind tunnel ends.

[0080] Preferably, before the high-pressure and vacuum systems of the wind tunnel are prepared for operation, the steps further include:

[0081] Charging the supercapacitor battery pack 81 through the charger 10.

[0082] Preferably, after the operation of the wind tunnel ends, the steps further include:

[0083] Charging the supercapacitor battery pack 81 through the charger 10 to prepare for the next operation of the wind tunnel.

[0084] The hypersonic wind tunnel heater system based on supercapacitors and its control method proposed by the present invention can achieve high-power transient heating of the hypersonic wind tunnel and can operate in a direct heating mode. The system powers heating devices such as heating wires or heating tapes inside the heater through a supercapacitor battery pack 81 and a power regulator 82, enabling the heating wires or heating tapes to generate heat. The gas flows through the heated heating wires or heating tapes and exchanges heat with them, achieving a temperature increase.

[0085] The foregoing are only the preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art can understand that any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included within the protection scope of the present application, and will not be elaborated herein one by one.

Claims

1. A hypersonic wind tunnel heater system based on supercapacitors, including a heater (8), characterized in that, The heater (8) includes: A supercapacitor battery pack (81) for providing electrical energy; A power regulator (82) circuit-connected to the supercapacitor battery pack (81) for stable output of electrical energy during the heating process and capable of voltage control according to the control logic; An electrothermal material (83) circuit-connected to the power regulator (82) for converting the stable electrical energy output by the power regulator (82) into heat energy to exchange heat with the airflow flowing into the heater; The power of the supercapacitor battery pack (81) is: Let the total temperature of the wind tunnel operation be T0, the total pressure be P0, the diameter of the wind tunnel nozzle outlet be D, and the specific heat ratio of air be c p , all of which adopt the International System of Units. Then the flow rate of the wind tunnel is as follows: Without considering heat loss, assuming the temperature of the inlet gas of the heater system is the normal temperature of 300K, then the required power P of the heater system is: The required power P is the power of the supercapacitor battery pack (81); The capacitance of the supercapacitor module in the supercapacitor battery pack (81) is calculated according to the total operation time requirement of the wind tunnel, and the calculation formula is: Set the initial voltage of the supercapacitor battery pack as U0, the capacitance of the supercapacitor module as C, the required power of the heater system as P, the supply voltage of the supercapacitor battery pack as U1, and the total operating time of the wind tunnel as t. For the heater system that uses a buck DCDC for voltage stabilization control, it is required that the voltage U f > U1. During the total operating time of the wind tunnel, the total energy released by the supercapacitor module is P·t, and the real-time voltage U of the supercapacitor battery pack c , then there is: It is obtained that: Also according to the requirements of the heater system, U f > U1 Then it can be obtained that: Furthermore, the basic parameters of the supercapacitor module can be determined. Considering the long-term operation of the system, the capacitance of the supercapacitor module can be appropriately increased according to the above calculation results.

2. The hypersonic wind tunnel heater system based on supercapacitors according to claim 1, wherein The electrothermal material (83) uses an electric heating wire or an electric heating tape.

3. The hypersonic wind tunnel heater system based on supercapacitors according to claim 1, characterized in that It also includes a charger (10) for charging the supercapacitor battery pack (81).

4. The hypersonic wind tunnel heater system based on supercapacitors according to claim 3, characterized in that, The charger (10) uses 220V - 380V alternating current.

5. The hypersonic wind tunnel heater system based on supercapacitors according to any one of claims 1 to 4, characterized in that It also includes a temperature sensor. The temperature sensor is arranged at the outlet of the heater and circuit-connected to the power regulator (82). The power regulator (82) uses the temperature of the heater outlet collected by the temperature sensor as a control parameter to perform feedback control on the output stable electrical energy.

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