A high-pressure gas storage chamber exhaust protection device and its control method

Abstract

The present invention provides a high-pressure gas storage chamber exhaust protection device and its control method. The structure includes a protection plate, which is arranged on the outer side of the exhaust pipeline of the high-pressure gas storage chamber, and a flexible connection structure is provided between the protection plate and the high-pressure gas storage chamber. By arranging a protection plate behind the exhaust pipeline of the high-pressure gas storage chamber, the present invention enables most of the air flow to be discharged horizontally towards the far rear, ensuring the safety of surrounding objects and personnel; the flexible connection structure can reduce the impact and vibration on the wind tunnel equipment in the normal direction, protecting the safety of the equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of aerodynamic experimental equipment, and particularly relates to a high-pressure gas storage chamber exhaust protection device and a control method thereof. Background Art

[0002] The high-pressure gas storage chamber is one of the components of a free-piston shock tunnel. The working principle of a free-piston shock tunnel is to use high-pressure air to push a piston to rapidly compress the driving gas, achieving heating and pressurization of the driving gas, so as to obtain a stronger shock wave in the shock tube. The high-pressure gas pushing the piston is stored in the high-pressure gas storage chamber.

[0003] The high-pressure gas storage chamber includes structures such as an intake and an exhaust pipe. When the wind tunnel operation ends or stops due to other factors, the gas in the high-pressure gas storage chamber needs to be discharged to the atmosphere through an exhaust valve. The exhaust valve is generally located on the side of the bottom of the gas storage chamber to ensure that the high-speed gas is discharged horizontally towards the far rear. The exhaust valve usually does not open completely (usually opens 1 / 2 - 2 / 3), which changes the shape of the exhaust pipe flow channel, resulting in the deviation of the high-speed gas discharge angle from the horizontal direction; when the high-speed air flow at the exhaust outlet is supersonic, the pressure in the high-pressure gas storage chamber will affect the expansion angle of the outlet gas, and further cause some gas to deviate more from the horizontal direction.

[0004] Since the high-pressure gas storage chamber is generally placed on the ground and the exhaust valve is close to the ground, the deviation of the high-speed gas from the horizontal direction may cause damage to the ground or surrounding items and injury to personnel, posing a certain safety hazard. Therefore, it is necessary to design an exhaust protection device to avoid potential safety hazards caused by the discharge of high-pressure gas. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-pressure gas storage chamber exhaust protection device and a control method thereof. Through the design of a certain contraction angle and a variable span protection range, the protection requirements for high-speed air flows of different pressures are met, and the air flow direction is shot towards the far rear close to the horizontal direction, effectively protecting the surrounding walls and floors.

[0006] According to an object of the present invention, the present invention provides a high-pressure gas storage chamber exhaust protection device, including a protection plate, the protection plate is arranged outside the exhaust pipe of the high-pressure gas storage chamber, and a flexible connection structure is provided between the protection plate and the high-pressure gas storage chamber.

[0007] Further, the protection plate is an arc-shaped protection plate, the arc-shaped protection plate includes a fixed protection plate and a movable protection plate, a chute is arranged inside the fixed protection plate, and the two movable protection plates are slidably arranged in the chute.

[0008] Further, the flexible connection structure includes a base, a rotating shaft, and a spring. The base is fixedly connected to the high-pressure gas storage chamber. The bottom of the arc-shaped protection plate is hinged to the base through the rotating shaft, and the spring is provided between the bottom of the arc-shaped protection plate and the base.

[0009] Further, both the fixed protection plate and the movable protection plate are arc-shaped structures, and the straight lines of the movable protection plate and the fixed protection plate are the same.

[0010] Further, a position adjusting mechanism is further included. The position adjusting mechanism includes a connecting rod, a lead screw, and a servo motor. The tops of the two connecting rods are respectively hinged to the two movable protection plates, the bottoms of the two connecting rods are respectively hinged to the lifting nuts, the lifting nuts are sleeved on the lead screw, and the bottom of the lead screw is connected to the servo motor.

[0011] Further, the arc-shaped protection plate has an inclination angle of 2° to 3° upward with respect to the horizontal plane along the air flow discharge direction; the protection angle range of the arc-shaped protection plate is 80° to 140°.

[0012] Further, the angle of the fixed protection plate is 80°, and the angle of the movable protection plate is 35°.

[0013] Further, the connection position of the connecting rod and the movable protection plate is located at the position 10° inside the movable protection plate.

[0014] Further, a protection ring is provided outside the high-pressure gas storage chamber. The protection ring is arranged outside the exhaust pipe, and the arc-shaped protection plate is tightly installed against the protection ring.

[0015] According to another object of the present invention, the present invention provides a control method for a high-pressure gas storage chamber exhaust protection device, including the following steps:

[0016] S1, obtaining the air flow velocity at the exhaust valve outlet through formula (1), and obtaining the outlet mass flow rate by combining with the exhaust valve area;

[0017]

[0018] In the above formula (1): p1 is the outlet atmospheric pressure, p0 is the gas storage chamber pressure, is the outlet Mach number, and γ is the adiabatic index;

[0019] S2, obtaining the impact force of the air flow on the normal direction of the arc-shaped protection plate according to the one-dimensional momentum equation of the gas (2), and then selecting a spring with a suitable elastic coefficient to ensure that the amplitude of the arc-shaped protection plate does not exceed 1° after being impacted by the air flow;

[0020] ∑Fn = q m V n (2)

[0021] Among them, when the airflow at the outlet is near the speed of sound, the airflow flow rate is the largest at this time, and there is no problem of expansion waves. If momentum loss is not considered, the maximum normal impact force of the airflow can be obtained;

[0022] In the above formula (2), F n is the normal force received by the protective plate, q m is the airflow flow rate, and V n is the normal velocity of the airflow;

[0023] S3. When it is obtained from formula (1) that the pressure in the high-pressure gas storage chamber is greater than 1.893 atmospheres, the airflow in the exhaust valve is at the speed of sound. The airflow experiences a series of expansion waves at the outlet, the airflow angle turns and accelerates to supersonic speed. At this time, the higher the pressure in the high-pressure gas storage chamber, the greater the airflow outlet velocity. According to formula (3), the greater the degree of airflow turning, and thus the wider the influence range of the airflow; At this time, combining the exhaust valve and the position of the arc-shaped protection 5, the maximum protection range of the arc-shaped protection plate is determined as:

[0024]

[0025] In formula (3), θ is the airflow turning angle, is the outlet Mach number, and γ is the adiabatic index;

[0026] Formula (3) shows the angle required to turn from the speed of sound to . Since the normal impact force is the largest when the outlet airflow speed is near the speed of sound, the unit impact force on the airflow impact position of the arc-shaped protection plate is also the largest at this time; and the larger the Mach number, the larger the airflow expansion angle, and the smaller the unit impact force on the airflow impact position on the arc-shaped protection plate.

[0027] The technical solution of the present invention is to set a protection plate behind the exhaust pipeline of the high-pressure gas storage chamber, so that most of the airflow is discharged horizontally to the far rear, ensuring the safety of surrounding items and personnel; The flexible connection structure can reduce the impact and vibration on the wind tunnel equipment in the normal direction and protect the safety of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0029] Figure 1Schematic diagram of the structure of an embodiment of the present invention;

[0030] Figure 2 Schematic diagram of the structure of the arc-shaped protection plate of an embodiment of the present invention;

[0031] Figure 3 Schematic diagram of the structure of the fixed protection plate in an embodiment of the present invention.

[0032] In the figure, 1, high-pressure gas storage chamber; 2, exhaust pipe; 3, protection ring; 4, exhaust valve; 5, arc-shaped protection plate; 6, fixed protection plate; 7, movable protection plate; 8, sliding groove; 9, base; 10, rotating shaft; 11, spring; 12, connecting rod; 13, lead screw; 14, servo motor; 15, lifting nut. Specific embodiments

[0033] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0034] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0035] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, "a plurality" means two or more, unless otherwise specifically defined. In addition, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] Embodiment 1

[0037] As Figures 1 - 3 shown,

[0038] A high-pressure gas storage chamber exhaust protection device includes an arc-shaped protection plate 5, a flexible connection structure, and a position adjustment mechanism. The arc-shaped protection plate 5 is arranged outside the exhaust pipe 2 of the high-pressure gas storage chamber 1. Most of the airflow is discharged horizontally to the far rear through the arc-shaped protection plate 5, ensuring the safety of surrounding items and personnel.

[0039] In this embodiment, as Figure 1 shown, the diameter of the exhaust pipe 2 of the high-pressure gas storage chamber 1 is 100 mm, the exhaust pipe 2 deviates from the geometric center of the tank body of the high-pressure gas storage chamber 1 by 200 mm, and the exhaust valve 4 is arranged on the upper side of the exhaust pipe 2. A protection ring 3 is arranged outside the high-pressure gas storage chamber 1. The protection ring 3 is arranged outside the exhaust pipe 2. The protection ring 3 is fixedly connected to the outer wall of the high-pressure gas storage chamber 1 through a flange. The inner diameter of the protection ring 3 is 800 mm. Horizontally, the outlet of the protection ring 3 is 500 mm away from the outlet of the exhaust pipe 2.

[0040] As Figure 1 and Figure 2 shown, the arc-shaped protection plate 5 is installed closely against the protection ring 3. The diameter of the arc-shaped protection plate 5 is the same as that of the protection ring 3, both being 800 mm. According to numerical simulation and actual judgment, the angle between the high-speed airflow and the horizontal direction during exhaust is 10-20° (by default, an average of 15° under different working conditions). Therefore, the length of the arc-shaped protection plate 5 is calculated based on the minimum exhaust angle and the distance between the exhaust valve 4 and the arc-shaped protection plate 5. The length of the arc-shaped protection plate 5 is designed to be 800 mm.

[0041] As Figure 2 and Figure 3 shown, the arc-shaped protection plate 5 includes a fixed protection plate 6 and a movable protection plate 7. The arc-shaped protection plate 5 is used to receive the impact of the high-speed airflow and change the direction of the high-speed airflow. A chute 8 is arranged inside the fixed protection plate 6. Two movable protection plates 7 are slidably arranged in the chute 8 and can slide along the chute 8. Thus, by adjusting the sliding of the movable protection plate 7 in the chute 8, the unfolding degree of the movable protection plate 7 and the fixed protection plate 6 can be adjusted, and the protection range can be accurately adjusted.

[0042] The flexible connection structure includes a base 9, a rotating shaft 10, and a spring 11. The base 9 is connected to the high-pressure gas storage chamber 1 through bolts; the bottom of the arc-shaped protection plate 5 is hinged to the base 9 through the rotating shaft 10, and a spring 11 is arranged between the bottom of the arc-shaped protection plate 5 and the upper surface of the base 9.

[0043] The position adjustment mechanism includes a connecting rod 12, a lead screw 13, and a servo motor 14. The top ends of the two connecting rods 12 are respectively hinged to the two movable protective plates 7, and the bottom ends of the two connecting rods 12 are respectively hinged to the lifting nuts 15. The lifting nuts 15 are sleeved on the lead screw, and the bottom of the lead screw is connected to the servo motor 14. By driving the lead screw to rotate through the servo motor 14, the deployment angle of the two movable protective plates 7 on the fixed protective plate 6 can be realized, and the protection range can be accurately changed.

[0044] The basic shape of the arc-shaped protective plate 5 is an arc surface. Both the fixed protective plate 6 and the movable protective plate 7 are arc-shaped structures, and the arc radii of the upper surface of the movable protective plate 7 and the lower surface of the fixed protective plate 6 are the same, so that the movable protective plate 7 can overlap and deploy with the fixed protective plate 6.

[0045] By numerically calculating and simulating the exhaust conditions under different working conditions, it is found that when there is a small contraction angle (2° - 3°) of the arc-shaped protective plate 5 along the air flow discharge direction, the overall discharge direction of the air flow is more inclined to the horizontal, and the protection effect is better. After simulating different working conditions, the contraction angle of the arc-shaped protective plate 5 is designed to be 3 degrees. Such a design makes the exhaust direction close to the horizontal direction under various working conditions. The numerical simulation method mainly uses the finite volume method to solve the flow field of the steady Reynolds-averaged N-S equation.

[0046] The air flow velocity at the outlet of the exhaust valve 4 is obtained by formula (1), and the outlet mass flow rate is obtained by combining with the area of the exhaust valve 4;

[0047]

[0048] In the above formula (1), p1 is the outlet atmospheric pressure, p0 is the pressure in the gas storage chamber, is the outlet Mach number, and γ is the adiabatic index. According to the one-dimensional momentum equation of the gas formula (2), the impact force of the air flow on the normal direction of the arc-shaped protective plate 5 is obtained, and then a spring 11 with a suitable elastic coefficient is selected to ensure that the amplitude of the arc-shaped protective plate 5 does not exceed 1° after being impacted by the air flow;

[0049] ∑F n =q m V n (2)

[0050] Among them, when the air flow at the outlet is near the speed of sound, the air flow rate is the largest at this time, and there is no problem of expansion wave. If the momentum loss is not considered, the maximum normal impact force of the air flow can be obtained.

[0051] In the above formula (2), F n is the normal force received by the protective plate, q m is the air flow rate, and V n is the normal velocity of the air flow.

[0052] When the pressure in the high-pressure gas storage chamber 1 is greater than 1.893 atmospheres obtained from Equation (1), the airflow in the exhaust valve 4 is at the speed of sound. The airflow experiences a series of expansion waves at the outlet, the airflow angle turns and accelerates to supersonic speed. At this time, the higher the pressure in the high-pressure gas storage chamber 1, the greater the outlet speed of the airflow. According to Equation (3), the greater the degree of airflow turning, and thus the wider the influence range of the airflow. At this time, the maximum protection range of the arc-shaped protection plate 5 should be determined by combining the positions of the exhaust valve 4 and the arc-shaped protection plate 5 as follows:

[0053]

[0054] In Equation (3), θ is the airflow turning angle, is the outlet Mach number, and γ is the adiabatic index. This equation indicates the angle required to turn from the speed of sound to . Since the normal impact force is the greatest when the outlet airflow speed is near the speed of sound, at this time, for the arc-shaped protection plate 5, the unit impact force at the airflow impact position is also the greatest; and the greater the Mach number, the greater the airflow expansion angle, and the smaller the unit impact force at the airflow impact position on the arc-shaped protection plate 5.

[0055] Considering the influence of the airflow influence range and impact force, the position adjustment mechanism adjusts the protection position of the arc-shaped protection plate 5 through a servo motor 14 and two connecting rods to achieve free adjustment of the protection range and protection intensity. The position adjustment mechanism includes a connecting rod 12, a lead screw 13, and a servo motor 14. The tops of the two connecting rods 12 are respectively hinged to two movable protection plates 7, and the bottoms of the two connecting rods 12 are respectively hinged to a lifting nut 15. The lifting nut 15 is sleeved on the lead screw, and the bottom of the lead screw is connected to the servo motor 14. By driving the lead screw to rotate through the servo motor 14, the deployment angle of the two movable protection plates 7 on the fixed protection plate 6 can be realized, and the protection range can be accurately changed.

[0056] In this embodiment, one end of the two connecting rods 12 with a length equal to the radius of the arc-shaped protection plate 5 is connected to the movable protection plate 7, and the other ends are connected together and constrained on a lifting nut 15. The lifting nut 15 is driven by the lead screw. The lead screw 13 is 300 mm long, and one end of the lead screw 13 is connected to the servo motor 14; the servo motor 14 is connected to the control system. The control system controls the rotation of the servo motor 14 by sending signals and drives the lead screw 13 to rotate, realizing the rise or fall of the lifting nut 15 on the lead screw, and thus changing the position of the movable protection plate 7. This structure is simple and reliable and can accurately control the protection range.

[0057] According to Equation (1), Equation (2), and the throat area when the exhaust valve 4 is opened to 2 / 3 of its area, the maximum normal impact force of the air flow on the arc-shaped protection plate 5 can be obtained, which is approximately 192 N. Considering the self-weight of the arc-shaped protection plate 5, preferably, in the flexible connection structure, a spring 11 with an elastic coefficient of 100 kN / m is used. At this time, the oscillation range of the spring 11 caused by the air flow impact does not exceed 2 mm, and the amplitude of the arc-shaped protection plate 5 does not exceed 1°.

[0058] In the current working state of the high-pressure gas storage chamber 1, the highest gas storage pressure is 7.6 MPa, and the highest exhaust Mach number is close to 3.5. At this time, the air flow turning angle exceeds 60°. After comprehensively analyzing factors such as the relative positions of the exhaust pipe 2, the arc-shaped protection plate 5, and the protection ring 3, as well as the length of the arc-shaped protection plate 5, the large protection angle range is determined to be 140°, and the small protection angle range is 80°.

[0059] The angle of the fixed protection plate 6 is 80°, and the angle of the movable protection plate 7 is 35°. In the minimum protection position, the movable protection plate 7 is completely retracted into the fixed protection plate 6, and in the maximum protection position, the movable protection plate 7 extends within a range of 30°.

[0060] The connection position of the connecting rod 12 and the movable protection plate 7 is located 10° inside the movable protection plate 7. When in the maximum protection position, the angle between the two connecting rods 12 is 90 degrees. If a larger protection range needs to be achieved in the design, during the design, the length of the connecting rod 12 can be increased, the connection position of the connecting rod 12 and the movable protection plate 7 can be changed, and the arc range of the movable protection plate 7 itself can be increased. During operation, the protection range of the arc-shaped protection plate 5 can be determined by the pressure in the high-pressure gas storage chamber 1, and the change of the protection range can be realized through the control system.

[0061] The exhaust protection device of the high-pressure gas storage chamber 1 of the present invention has been successfully applied to the high-pressure gas storage chamber 1 of the free piston shock tunnel. The pressure resistance of the high-pressure gas storage chamber 1 is 20 MPa. The operation results show that the exhaust air flow is well guided to the far rear under different working conditions, and the ground dust will not be blown up during the on-site test, effectively realizing the protection of the ground and the safety of the surrounding equipment and personnel, and ensuring the safe operation of the wind tunnel equipment.

[0062] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-pressure gas storage chamber exhaust protection device, characterized in that, It includes a protective plate which is arranged outside the exhaust pipeline of the high-pressure gas storage chamber, and a flexible connection structure is provided between the protective plate and the high-pressure gas storage chamber; the protective plate is an arc-shaped protective plate, and the arc-shaped protective plate includes a fixed protective plate and a movable protective plate. A chute is arranged inside the fixed protective plate, and the two movable protective plates are slidably arranged in the chute; it also includes a position adjustment mechanism which includes a connecting rod, a lead screw and a servo motor. The tops of the two connecting rods are respectively hinged to the two movable protective plates, the bottoms of the two connecting rods are respectively hinged to a lifting nut, the lifting nut is sleeved on the lead screw, and the bottom of the lead screw is connected to the servo motor; the flexible connection structure includes a base, a rotating shaft and a spring. The base is fixedly connected to the high-pressure gas storage chamber, the bottom of the arc-shaped protective plate is hinged to the base through the rotating shaft, and the spring is arranged between the bottom of the arc-shaped protective plate and the base.

2. The exhaust protection device for the high-pressure gas storage chamber according to claim 1, characterized in that, Both the fixed protective plate and the movable protective plate are arc-shaped structures, and the straight lines of the movable protective plate and the fixed protective plate are the same.

3. The exhaust protection device for the high-pressure gas storage chamber according to claim 1, characterized in that, Further, the arc-shaped protective plate has an upward inclination angle of 2° to 3° with respect to the horizontal plane along the gas flow discharge direction; the protection angle range of the arc-shaped protective plate is 80° to 140°.

4. The high-pressure gas storage chamber exhaust protection device according to claim 3, characterized in that The angle of the fixed protective plate is 80°, and the angle of the movable protective plate is 35°.

5. The high-pressure gas storage chamber exhaust protection device according to claim 4, characterized in that, The connection position of the connecting rod and the movable protective plate is at the 10° position inside the movable protective plate.

6. The exhaust protection device for the high-pressure gas storage chamber according to claim 5, wherein A protective ring is arranged outside the high-pressure gas storage chamber, the protective ring is arranged outside the exhaust pipeline, and the arc-shaped protective plate is installed closely against the protective ring.

7. The control method of the exhaust protection device for the high-pressure gas storage chamber according to claim 6, characterized in that, It includes the following steps: S1, obtain the gas flow velocity at the outlet of the exhaust valve through formula (1), and combine with the area of the exhaust valve to obtain the outlet mass flow rate; (1) In the above formula (1): is the outlet atmospheric pressure, is the pressure of the gas storage chamber, is the outlet Mach number, is the adiabatic index; S2, obtain the impact force of the gas flow on the normal direction of the arc-shaped protective plate according to the one-dimensional momentum equation of the gas (2), and then select a spring with a suitable elastic coefficient to ensure that the amplitude of the arc-shaped protective plate does not exceed 1° after being impacted by the gas flow; Among them, when the gas flow at the outlet is near the speed of sound, the gas flow rate is the largest at this time, and there is no problem of expansion wave. If the momentum loss is not considered, the maximum normal impact force of the gas flow can be obtained; In the above formula (2), F n is the normal force received by the protection plate, q m is the air flow rate, and V n is the normal velocity of the air flow; S3, when it is obtained through formula (1) that the pressure in the high-pressure gas storage chamber is greater than 1.893 atmospheres, the gas flow in the exhaust valve is at the speed of sound, and the gas flow experiences a series of expansion waves at the outlet. The gas flow angle turns and accelerates to supersonic speed. At this time, the higher the pressure in the high-pressure gas storage chamber, the greater the gas flow outlet speed. According to formula (3), the greater the degree of gas flow turning, so the influence range of the gas flow is wider; at this time, in combination with the positions of the exhaust valve and the arc-shaped protective plate 5, the maximum protection range of the arc-shaped protective plate is determined as: In Equation (3), is the airflow turning angle, is the exit Mach number, is the adiabatic index; Equation (3) shows the angle of deflection required to accelerate from the speed of sound to When the outlet gas flow velocity is near the speed of sound, the normal impact force is the largest, and at this time, the unit impact force on the gas flow impact position of the arc-shaped protection plate is also the largest; the larger the Mach number, the larger the gas flow expansion angle, and the smaller the unit impact force on the gas flow impact position on the arc-shaped protection plate.

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