Aerodynamic layout of gas piston heater for high Reynolds number hypersonic wind tunnel

Abstract

The present invention belongs to the field of hypersonic wind tunnel equipment, and discloses an aerodynamic layout of a gas piston heater for a high Reynolds number hypersonic wind tunnel. The aerodynamic layout of the gas piston heater includes a cold tank and a heater cylinder body connected in sequence from bottom to top, and a heating element is surrounded by the heater cylinder body; the internal cavity of the cold tank is a cold cavity, and the internal cavity of the heater cylinder body is a hot cavity; a cold air inlet is opened on the bottom surface of the cold tank, and the diameter of the cold air inlet is much smaller than the inner diameter of the cold cavity; a cold air outlet connected to the hot cavity is opened on the top surface of the cold tank, and a guide platform is arranged at the cold air outlet; a hot air outlet is opened on the top surface of the heater cylinder body. The aerodynamic layout of the gas piston heater adopts a gas piston driven operation mode in which cold air drives hot air, which can ensure that the hot air pressure and temperature at the hot air outlet are constant, and at the same time, it can make full use of the ultra-high pressure and ultra-high temperature hot air inside the hot cavity, so that the effective operation time of the high Reynolds number hypersonic wind tunnel is extended, which can reach 1 second to tens of seconds.

Description

Technical Field

[0001] The present invention belongs to the field of hypersonic wind tunnel equipment, and in particular relates to an aerodynamic layout of a gas piston heater for a high Reynolds number hypersonic wind tunnel. Background Art

[0002] Conventional hypersonic wind tunnels usually use air as the test medium, with a maximum operating Mach number of 10, a maximum total pressure of 12 MPa, a maximum total temperature of 1082 K, and a low Reynolds number. Due to the high gas velocity, reaching Mach numbers of 5 to 10, the violent expansion of the airflow through the nozzle will cause condensation of water vapor and carbon dioxide, resulting in uneven flow field and inaccurate test data, which is not allowed in hypersonic wind tunnel aerodynamic tests. Therefore, a heater needs to be set in a conventional hypersonic wind tunnel with high-speed air as the medium to heat the airflow to the required anti-condensation temperature. The heaters used in conventional hypersonic wind tunnels are usually divided into two types, namely: direct heating heaters and thermal storage heaters. Direct heating heaters are airflows that directly exchange heat with metal resistance strips or resistance wires to achieve airflow heating; direct heating heaters are composed of metal heating elements (resistance strips or resistance wires), thermal insulation layers, and integral forging-type pressure-bearing shells. The thermal storage heater preheats the internal thermal storage body through the metal heating element, and then the airflow exchanges heat with the thermal storage body to achieve airflow heating; the thermal storage heater is composed of a metal heating element (armored electric heating tube), a metal thermal storage body or a pebble bed thermal storage body, an insulation layer, and an integral forging type pressure-bearing shell. The maximum operating total temperature of the direct heating heater and the thermal storage heater is below 1373K, and the maximum total pressure is below tens of MPa, which can meet the conventional hypersonic wind tunnel test airflow heating requirements and the wind tunnel operation time requirements of several seconds to tens of seconds.

[0003] Since the high Reynolds number hypersonic wind tunnel can simulate high Reynolds number and high Mach number at the same time, the operating Mach number is much greater than 10, the maximum total pressure of the airflow is 200MPa, the maximum total temperature of the airflow is 2300K, and the wind tunnel Reynolds number is relatively high. In order to meet the heating needs of the test airflow and the requirements of the wind tunnel operation indicators, the heater of the high Reynolds number hypersonic wind tunnel needs to meet the following requirements:

[0004] 1. The maximum operating total pressure of the heater needs to reach 200MPa, and the maximum operating temperature needs to reach 2300K;

[0005] 2. The ultra-high temperature and ultra-high pressure airflow heated by the heater must meet the requirement that the wind tunnel operation time is greater than 1 second. The volume of the ultra-high temperature and ultra-high pressure test airflow provided by the heater for a single test needs to be several cubic meters;

[0006] 3. During the operation of the high Reynolds number hypersonic wind tunnel, the heater outlet airflow temperature and pressure must remain constant at 200 MPa and 2300 K;

[0007] 4. The ultra-high temperature and ultra-high pressure test air is clean and pollution-free.

[0008] The direct heating heaters and heat storage heaters used in conventional hypersonic wind tunnels cannot meet the heating temperature and operating pressure requirements of high Reynolds number hypersonic wind tunnel test airflow. In order to obtain ultra-high temperature and ultra-high pressure test airflow, the commonly used means are to use shock wind tunnels or detonation drive methods. However, the ultra-high temperature and ultra-high pressure test airflow obtained by shock wind tunnels or detonation drive methods is short-lived, about a few milliseconds to hundreds of milliseconds, and the impact load and aerodynamic load during the start-up process of shock wind tunnels or detonation drive methods are difficult to distinguish, resulting in the accuracy of aerodynamic data being much lower than that of conventional hypersonic wind tunnels; or using non-metallic heating element heaters to directly heat the test airflow and increase the pressure to 2300K and 200MPa, and then opening the heater outlet valve, but this will cause the heater outlet airflow temperature and pressure to gradually decrease, which does not meet the high Reynolds number hypersonic wind tunnel operation index requirements.

[0009] In order to solve the problems that direct-heated heaters and thermal storage heaters cannot meet the requirements of airflow heating temperature and operating pressure in high-Reynolds number hypersonic wind tunnel tests, the shock wave wind tunnel or detonation drive mode has a short operating time, and the heater directly releases hot air, resulting in a gradual decrease in outlet airflow temperature and pressure, there is an urgent need to develop an aerodynamic layout of a gas piston heater for high-Reynolds number hypersonic wind tunnels. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide an aerodynamic layout of a gas piston heater for a high Reynolds number hypersonic wind tunnel, so as to solve the problems that direct heating heaters and thermal storage heaters cannot meet the requirements of airflow heating temperature and operating pressure in high Reynolds number hypersonic wind tunnel tests, the shock wave wind tunnel or detonation drive mode has a short operating time, and the heater directly releases hot air, causing the outlet airflow temperature and pressure to gradually decrease.

[0011] The gas piston heater aerodynamic layout for a high Reynolds number hypersonic wind tunnel of the present invention is characterized in that the gas piston heater aerodynamic layout comprises a cold tank and a heater cylinder body connected in sequence from bottom to top, and the heater cylinder body surrounds a heating element; the internal cavity of the cold tank is a cold cavity, and the internal cavity of the heater cylinder body is a hot cavity; a cold air inlet is provided on the bottom surface of the cold tank, and the diameter of the cold air inlet is much smaller than the inner diameter of the cold cavity; a cold air outlet connected to the hot cavity is provided on the top surface of the cold tank, and a guide platform is provided at the cold air outlet; a hot air outlet is provided on the top surface of the heater cylinder body;

[0012] The cold air inlet, cold cavity, guide platform, hot cavity, hot air outlet and heating element are on the same central axis;

[0013] The guide platform is a rotating body, which consists of the head, transition body, guide plate, tail and baffle from bottom to top;

[0014] The head is a cylinder I, the vertical distance between the lower end surface of the head and the bottom surface of the cold cavity is H1, and the annular flow area of ​​the lower end surface of the head is larger than the flow area of ​​the cold air inlet; the transition body is a cone with a smaller diameter at the bottom and a larger diameter at the top; the guide plate is a circular ring extending horizontally outward from the top surface of the transition body, the outer diameter of the guide plate is larger than the diameter of the cold air outlet and smaller than the inner diameter of the cold cavity, the vertical distance between the top surface of the guide plate and the lower surface of the cold cavity is h, h

[0015] When the pressure and temperature of the nitrogen inside the hot chamber reach the set values, ultra-high pressure and ultra-high temperature hot gas is formed, and the heating element stops working; when the diaphragm downstream of the hot gas outlet ruptures or the valve opens, an equal volume of ultra-high pressure cold air flows into the cold gas inlet, and after being equalized, decelerated and adjusted in the direction of the air flow by the cold chamber and the guide table, it enters the hot chamber, forming a gas piston, driving the ultra-high pressure and ultra-high temperature hot gas in the hot chamber to flow out evenly from the hot gas outlet, and continuously maintaining the total temperature and total pressure of the hot gas at the hot gas outlet constant until the ultra-high pressure and ultra-high temperature hot gas is discharged, and the operation of the high Reynolds number hypersonic wind tunnel is terminated.

[0016] Furthermore, the hot chamber contains ultra-high temperature and ultra-high pressure hot gas, and the ultra-high temperature and ultra-high pressure hot gas is nitrogen with a maximum temperature of 2300K and a maximum pressure of 200MPa.

[0017] Furthermore, an ultra-high pressure cold air flow is introduced into the cold air inlet, and the ultra-high pressure cold air flow is nitrogen with a room temperature of 323K and a pressure range of 200MPa to 250MPa.

[0018] The aerodynamic layout of the gas piston heater for a high Reynolds number hypersonic wind tunnel of the present invention adopts an ultra-high pressure cold airflow to drive ultra-high pressure and ultra-high temperature hot air, that is, the ultra-high pressure cold airflow is used to form a gas piston to drive the ultra-high pressure and ultra-high temperature hot air operation mode, and the total temperature and total pressure of the hot air at the hot air outlet are maintained constant. After the pressure and temperature of the nitrogen in the hot chamber reach the set value, ultra-high pressure and ultra-high temperature hot air is formed, and the heating element stops working; when the diaphragm downstream of the hot gas outlet ruptures or the valve is opened, an equal volume of ultra-high pressure cold air enters the cold air inlet, and after the flow is equalized, decelerated and the flow direction of the airflow is adjusted by the cold chamber and the guide table, it enters the hot chamber to form a gas piston, driving the ultra-high pressure and ultra-high temperature hot air in the hot chamber to flow out evenly from the hot gas outlet, and continuously maintaining the total temperature and total pressure of the hot gas at the hot gas outlet constant until the ultra-high pressure and ultra-high temperature hot air is emptied, and the operation of the high Reynolds number hypersonic wind tunnel ends.

[0019] ​The aerodynamic layout of the gas piston heater for a high Reynolds number hypersonic wind tunnel of the present invention adopts a gas piston driven operation mode in which cold air drives hot air, which can ensure that the hot air pressure and temperature at the hot air outlet are constant. At the same time, the ultra-high pressure and ultra-high temperature hot air inside the hot cavity can be fully utilized, so that the high Reynolds number hypersonic wind tunnel has the longest effective operation time, which can reach 1 second to tens of seconds. The cold cavity and the guide table set at the lower end of the heater can avoid the direct jet of the ultra-high pressure cold air flow entering the hot cavity and mixing with the ultra-high pressure and ultra-high temperature hot air, play a role in equalizing the flow and pressure of the ultra-high pressure cold air flow, and at the same time reduce the flow rate of the ultra-high pressure cold air flow, reduce the mixing speed of cold air and hot air, improve the gas piston driving efficiency and the utilization rate of hot air, and extend the effective operation time of the high Reynolds number hypersonic wind tunnel. The use of the guide table structure can further reduce the upward flow rate of the ultra-high pressure cold air flow, change the flow direction of the ultra-high pressure cold air flow, avoid the upward spray of cold air, reduce the mixing speed of cold air and hot air, improve the gas piston driving efficiency and the utilization rate of hot air, and extend the effective operation time of the wind tunnel.

[0020] In short, the aerodynamic layout of the gas piston heater for a high Reynolds number hypersonic wind tunnel of the present invention adopts a gas piston driven operation mode in which cold air drives hot air, which can ensure that the hot gas pressure and temperature at the hot gas outlet are constant, and at the same time can make full use of the ultra-high pressure and ultra-high temperature hot gas inside the hot cavity, thereby extending the effective operation time of the high Reynolds number hypersonic wind tunnel, which can reach 1 second to tens of seconds. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of the aerodynamic layout of a gas piston heater for a high Reynolds number hypersonic wind tunnel according to the present invention;

[0022] Figure 2 The present invention is a schematic diagram of the structure of a guide table in the aerodynamic layout of a gas piston heater for a high Reynolds number hypersonic wind tunnel.

[0023] In the figure, 1. cold air inlet; 2. cold chamber; 3. flow guide table; 4. hot chamber; 5. hot air outlet; 6. heating element;

[0024] 301. Head; 302. Transition body; 303. Guide plate; 304. Tail; 305. Baffle. DETAILED DESCRIPTION

[0025] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0026] Example 1

[0027] like Figure 1As shown, the aerodynamic layout of the gas piston heater for a high Reynolds number hypersonic wind tunnel of this embodiment includes a cold tank and a heater cylinder body connected in sequence from bottom to top, and a heating element 6 is surrounded by the heater cylinder body; the internal cavity of the cold tank is a cold cavity 2, and the internal cavity of the heater cylinder body is a hot cavity 4; a cold air inlet 1 is opened on the bottom surface of the cold tank, and the diameter of the cold air inlet 1 is much smaller than the inner diameter of the cold cavity 2; a cold air outlet connected to the hot cavity 4 is opened on the top surface of the cold tank, and a guide platform 3 is arranged at the cold air outlet; a hot air outlet 5 is opened on the top surface of the heater cylinder body;

[0028] The cold air inlet 1, the cold cavity 2, the guide platform 3, the hot cavity 4, the hot air outlet 5 and the heating element 6 are coaxial;

[0029] The inner diameter of the cold chamber 2 is much larger than the diameter of the cold air inlet 1. The cold chamber 2 has a large volume and can evenly distribute the ultra-high pressure cold air flow at the cold air inlet 1, making the speed, density and pressure of the ultra-high pressure cold air flow uniform, thereby ensuring that the speed, density and pressure of the air flow entering the guide platform 3 are uniform, thereby improving the gas piston driving efficiency and the hot gas utilization rate.

[0030] The hot chamber 4 adopts an internal hollow structure, and a heating element 6 surrounds the hot chamber 4. The heating element 6 will not disturb the airflow inside the hot chamber 4, which can improve the gas piston driving efficiency and hot gas utilization rate, and extend the effective operation time of the high Reynolds number hypersonic wind tunnel.

[0031] like Figure 2 As shown, the guide platform 3 is a spiral body, which includes, from bottom to top, a head 301, a transition body 302, a guide plate 303, a tail 304, and a baffle 305; the guide platform 3 can reduce the flow rate of the ultra-high pressure cold air flow and adjust the flow direction of the ultra-high pressure cold air flow, reduce the mixing speed of cold air and hot air, and improve the gas piston driving efficiency and hot gas utilization rate.

[0032] The head 301 is a cylinder I, and the vertical distance between the lower end surface of the head 301 and the bottom surface of the cold chamber 2 is H1. The annular flow area of ​​the lower end surface of the head 301 is larger than the flow area of ​​the cold air inlet 1. The head 301 can guide the cold air flow flowing vertically upward into the cold chamber 2 to avoid the central jet, and ensure that the air flow velocity, density and pressure in the entire cold chamber 2 are uniform;

[0033] The transition body 302 is a cone with a smaller diameter at the bottom and a larger diameter at the top. The upper end of the transition body 302 is connected to the guide plate 303;

[0034] The guide plate 303 is a circular ring extending horizontally outward from the top surface of the transition body 302. The outer diameter of the guide plate 303 is larger than the diameter of the cold air outlet and smaller than the inner diameter of the cold chamber 2. The vertical distance between the upper surface of the guide plate 303 and the top surface of the cold chamber 2 is h, h

[0035] The tail portion 304 is a cylinder II, and the outer diameter of the tail portion 304 is equal to the outer diameter of the top surface of the transition body 302. The tail portion 304 can further reduce the velocity of the ultra-high pressure cold air flow, and then reduce the mixing velocity of the ultra-high pressure cold air flow and the ultra-high temperature and ultra-high pressure hot air, thereby improving the gas piston driving efficiency and the hot gas utilization rate;

[0036] The baffle 305 is a cone with a smaller diameter at the top and a larger diameter at the bottom, extending outward and downward from the top surface of the tail 304, and the cone angle of the baffle 305 is in the range of 30° to 60°. The baffle 305 can further reduce the upward flow velocity of the ultra-high pressure cold air flow, change the flow direction of the ultra-high pressure cold air flow, avoid upward jet flow, ensure that the ultra-high pressure cold air flow and the ultra-high temperature and ultra-high pressure hot air form a relatively uniform interface, thereby reducing the mixing speed of cold air and hot air, and continuing to improve the gas piston driving efficiency and hot gas utilization rate.

[0037] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and the embodiments, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, other improvements and modifications can be easily realized without departing from the principles of the present invention, and the present invention is not limited to the specific details and the legends shown and described here.​

Claims

1. An aerodynamic layout of a gas piston heater for a high Reynolds number hypersonic wind tunnel, characterized in that: The pneumatic layout of the gas piston heater comprises a cold tank and a heater cylinder body connected in sequence from bottom to top, the heater cylinder body surrounds a heating element (6); the internal cavity of the cold tank is a cold cavity (2), and the internal cavity of the heater cylinder body is a hot cavity (4); the bottom surface of the cold tank is provided with a cold air inlet (1), the diameter of the cold air inlet (1) is much smaller than the inner diameter of the cold cavity (2); the top surface of the cold tank is provided with a cold air outlet connected to the hot cavity (4), and a guide platform (3) is provided at the cold air outlet; the top surface of the heater cylinder body is provided with a hot air outlet (5); The cold air inlet (1), the cold cavity (2), the guide platform (3), the hot cavity (4), the hot air outlet (5) and the heating element (6) are coaxial with each other; The guide platform (3) is a rotating body, which comprises, from bottom to top, a head (301), a transition body (302), a guide plate (303), a tail (304) and a baffle (305); The head (301) is a cylinder I, the vertical distance between the lower end surface of the head (301) and the bottom surface of the cold chamber (2) is H1, and the annular flow area of ​​the lower end surface of the head (301) is larger than the flow area of ​​the cold air inlet (1); the transition body (302) is a cone with a smaller diameter at the bottom and a larger diameter at the top; the guide plate (303) is a circular ring extending horizontally outward from the top surface of the transition body (302), the outer diameter of the guide plate (303) is larger than the diameter of the cold air outlet and smaller than the inner diameter of the cold chamber (2), and the guide plate (303) is The vertical distance between the top surface of the guide plate (303) and the lower surface of the cold chamber (2) is h, h<H1, and the gap between the upper surface of the guide plate (303) and the top surface of the cold chamber (2) forms an annular air inlet; the tail (304) is a cylinder II, and the outer diameter of the tail (304) is equal to the outer diameter of the top surface of the transition body (302); the baffle (305) is a cone cylinder with a smaller diameter at the top and a larger diameter at the bottom, extending outward and downward from the top surface of the tail (304), and the cone angle range of the baffle (305) is 30° to 60°; When the pressure and temperature of the nitrogen in the hot chamber (4) reach the set values, ultra-high pressure and ultra-high temperature hot gas is formed, and the heating element (6) stops working; when the diaphragm downstream of the hot gas outlet (5) ruptures or the valve is opened, an equal volume of ultra-high pressure cold air flows into the cold gas inlet (1), and after being equalized, decelerated and adjusted in the direction of the air flow through the cold chamber (2) and the guide platform (3), enters the hot chamber (4), forming a gas piston, driving the ultra-high pressure and ultra-high temperature hot gas in the hot chamber (4) to flow out evenly from the hot gas outlet (5), and continuously maintaining the total temperature and total pressure of the hot gas at the hot gas outlet (5) constant until the ultra-high pressure and ultra-high temperature hot gas is exhausted, and the operation of the high Reynolds number hypersonic wind tunnel ends.

2. The aerodynamic layout of the gas piston heater for a high Reynolds number hypersonic wind tunnel according to claim 1, characterized in that: The hot chamber (4) contains ultra-high temperature and ultra-high pressure hot gas, and the ultra-high temperature and ultra-high pressure hot gas is nitrogen with a maximum temperature of 2300K and a maximum pressure of 200MPa.

3. The aerodynamic layout of the gas piston heater for a high Reynolds number hypersonic wind tunnel according to claim 1, characterized in that: The cold air inlet (1) is introduced with an ultra-high pressure cold air flow, wherein the ultra-high pressure cold air flow is nitrogen at a room temperature of 323K and a pressure range of 200 MPa to 250 MPa.

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