CN109059643B - An air cannon negative pressure launching mechanism - Google Patents

Abstract

A negative pressure launching mechanism of an air cannon is characterized in that a piston is positioned in a control air chamber; the gun barrel is arranged in the center of the outer end face of one end of the control air chamber, and the other end of the control air chamber is communicated with the vacuum tank; the output end of the air pump is respectively communicated with the air inlet of the high-pressure air tank and the three-way pipe, when vacuum low-speed impact is needed, the gun barrel and the vacuum tank are both vacuumized, and the pressure of the air chamber and the pressure of the high-pressure air tank are 0 or negative pressure according to the test requirement. When in launching, the launching valve is opened to ensure that the air pressure of the second air chamber is lower than that of the first air chamber; the air in the first air chamber and the high-pressure air tank pushes the piston to move towards the gun barrel, so that the pressure enters the gun barrel to push the bird body to launch. The invention can realize negative pressure emission to the bird body in a vacuum state, simulate the collision process of the bird to the aircraft engine, provide an effective means for the bird collision resistance design of the engine in China, and has important significance for improving the bird collision test technology and the engine design level of the engine in China.

Description

An air cannon negative pressure launching mechanism

technical field

The invention relates to the field of bird body drive design of a bird strike system, in particular to a negative pressure launching mechanism.

Background technique

Bird strikes are accidents that occur when an aircraft such as an aircraft flying in the air collides with a flying bird. With the rapid development of the civil aviation industry, the bird strike accident has become one of the most serious safety threats to civil aviation. According to the United Airlines report, from 1990 to 2008, US civil aviation reported a total of 89,727 collisions between animals and civil aircraft, of which 97.4% were caused by birds. Relevant data show that the windward side of the aircraft, including the windshield, radome, engine, leading edge of the wing and leading edge of the tail, is the most vulnerable to bird strikes.

The engine is the power source of the aircraft. Once damaged by a bird strike, a catastrophic accident is unavoidable. Therefore, it is very important to solve the problem of anti-bird collision of the engine. Generally, a launching device is used to accelerate the bird body and hit the engine blades at high speed. The bird strike damage of the engine is mainly concentrated in the damage of the fan blades. The bird strike test in the static state cannot meet the load state in the anti-bird strike design process, and the bird strike in the rotating state is limited by the power of the rotating tester. It is carried out in a vacuum box. If the bird body enters the vacuum box together with the high-pressure air of the air gun, it will cause the vacuum box to explode or the tester will be damaged due to the overload of air resistance. Therefore, measures must be taken to ensure that as little air as possible enters the vacuum box. The present invention It is of great significance for the anti-bird impact design of the engine.

According to Article 33.76 of the "Airworthiness Regulations for Aero Engines" (CCAR33-R2) (Second Amendment on March 15, 2011) formulated by the Civil Aviation Administration of China, the design of the engine must ensure that the aircraft engine is inhaled 1.8 ~ 3.6 kg (4 ~8 lbs), the engine shall not stop and the power loss shall not exceed 25%.

In the invention with the publication number of CN101338993A, the inventor proposes a same-source gas valve pushing device, which is mainly used for the bullet drive of the Hopkinson rod. In the invention with the publication number CN102252562A, the inventor proposes an air-floating piston launching device, which is used for bird body launch in a bird strike experiment. The two inventions and creations both use the pressure difference between the two ends of the piston to push the piston, so that one end of the air chamber is sealed, so as to ensure the direction of the air flow during inflation and launch. A common feature of these two inventions is that the low-pressure end is standard atmospheric pressure when inflating or launching, so the air pressure in the air chamber must be higher than the standard atmospheric pressure to work properly. In the invention and creation with the announcement number CN205642784U, the inventor proposed an impact test vacuum box sealing device, which is used for the impact test of the test piece in a vacuum state, which solves the problem that the high-pressure gas driving the projectile does not enter the vacuum box. Its gas tank firing pressure must be positive pressure.

However, for the bird strike engine test, in order to ensure that the impact occurs under vacuum, the barrel is evacuated along with the vacuum box where the engine blades are located. When the impact speed is low, the firing pressure of the gas tank is required to be lower than 1 standard atmospheric pressure, and the relative pressure is negative pressure at this time to ensure that the projectile speed meets the requirements. At this time, the above three inventions will not be used. At present, there is no negative pressure bird strike launch system suitable for vacuum state at home and abroad.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies in the prior art that cannot meet the requirements of the lower impact velocity test, the present invention proposes a negative pressure launching mechanism for an air cannon.

The invention includes a vacuum tank, a control air chamber, a piston, an air pump and a high-pressure air tank, wherein: the piston is located in the control air chamber. The control air chamber is divided into a first air chamber and a second air chamber; the end face of one end of the control air chamber is installed with a front flange, and the end face of the other end is installed with a rear flange. The gun barrel is installed in the center of the outer end face of the front flange; one end of the three-way pipe connected to the vacuum tank is communicated with the control air chamber through the rear flange. The launch valve is mounted on the tee between the control air chamber and the vacuum tank. The high-pressure air tank is located outside the control air chamber, and is connected to the control air chamber at 1/2 of the axial length of the control air chamber. The output end of the air pump is respectively connected with the air inlet of the high-pressure air tank and the three-way pipe through pipelines, and the interface between the air pump and the three-way pipe is located between the launch valve and the control air chamber. A second intake valve is installed on the pipeline between the air pump and the high-pressure air tank, and a first intake valve is installed on the pipeline between the air pump and the three-way pipe.

The piston is composed of a piston rod, a pneumatic push plate at one end of the piston rod, and a support plate at the other end of the piston rod. The axial length of the piston is 2/3 of the axial length of the control air chamber; the axial length of the air pressure push plate is 1/6 of the axial length of the piston, and the axial length of the support plate is also 1/6 of the axial length of the piston.

The diameter of the air pressure pushing plate and the diameter of the supporting plate are the same as the inner diameter of the control air chamber, and the air pressure pushing plate and the supporting plate are respectively slidably matched with the control air chamber.

There are 4 fan-shaped grooves symmetrically distributed on the circumference of the support plate; a piston sealing ring is embedded at the outer edge of the outer end surface of the support plate. The diameter of the piston rod is 1/6 times the diameter of the control air chamber.

The radial depth of the fan-shaped groove on the circumference of the support disk is 1/6 of the diameter of the support disk, and the angle between the two sides of each fan-shaped groove is 60°

The first air chamber of the control air chamber is the cavity between the air pressure pushing plate and the front flange plate, and the second air chamber is the cavity between the rear flange plate and the air pressure pushing plate.

The purpose of the present invention is to realize the negative pressure driving the projectile and complete the impact test on the target.

In order to solve the problem of the negative pressure launch of the bird body in a vacuum state, the invention connects the launch valve to the vacuum tank through a pipeline; a piston is installed in the control air chamber, and the control air chamber is divided into a first air chamber and a second air chamber , the first air chamber is used to store and release the high-pressure air used for launching the bird body, and the second air chamber is the movement stroke of the piston when launching. Before the start of the negative pressure bird strike experiment, the vacuum tank and gun barrel were evacuated. The first air inlet valve controls the air pump to input high-pressure air from one end of the rear flange plate of the air chamber into the second air chamber, and the pressure of the high-pressure air is more than 1.5 times that of the emitted gas. After the high-pressure gas enters the second air chamber, the air pressure pushing end of the piston moves in the direction of the gun barrel due to the pressure difference on both sides and touches the inner end face of the front flange, and the piston sealing ring makes the first air chamber and the gun barrel close to each other. isolated and sealed. After the second air chamber is inflated, use the second intake valve to inflate the high-pressure air tank and the first air chamber. Due to the sealing effect of the piston sealing ring, a sealed space is formed between the piston and the first air chamber, and the high-pressure air It will be sealed in the first air chamber, so that the air pressure in the first air chamber is higher than the air pressure in the gun barrel. After the first air chamber is inflated, the launch valve is opened, and the high-pressure gas sealed in the second air chamber will enter the vacuum tank through the pipeline, resulting in a sudden drop in the air pressure of the second air chamber. The first air chamber is still high-pressure gas. Due to the unbalanced force on the push end of the piston, the piston moves to one end of the rear flange under the action of the high air pressure of the first air chamber until it touches the rear flange. The movement of the piston makes the piston sealing ring separate from the front flange, and the air chamber and the gun barrel are connected. The enclosed high-pressure air will enter the gun barrel from the high-pressure air tank through the first air chamber instantly, and the high-pressure gas will push the bird in the gun barrel. The body is accelerated to realize the bird strike test.

When the bird strike test is performed, the speed of the bird body varies. Since the gun barrel is in a vacuum state, when a low-speed bird strike is required, the firing pressure of the air gun may be 0 or even negative pressure; since the gun barrel pressure is a vacuum, at this time The launch speed is equivalent to the launch speed when the pressure of the high-pressure gas tank is 1 standard atmosphere during the test in the atmospheric environment. However, the existing gas cannon launching mechanism cannot work normally when the launching pressure is 0 or negative pressure. Therefore, in the present invention, a vacuum tank is connected to the launching valve of the launching mechanism. When vacuum low-speed impact is required, both the gun barrel and the vacuum tank are evacuated, and the pressure of the first air chamber and the high-pressure air tank is set to 0 or negative pressure according to the test requirements. When launching, open the launch valve. Since the launch valve is connected with a vacuum tank, the air pressure in the second air chamber will be lower than the first air chamber. The air in the first air chamber and the high-pressure air tank pushes the piston to move toward the rear flange. The air in the air chamber and the high-pressure air tank enters the gun barrel and pushes the bird to launch.

In the course of aero-engine service, foreign object inhalation damage is a problem that must be taken seriously in the design of civil aero-engines. When the engine inhales various foreign objects, such as birds, stones, sand, bolts or rivets, the blades of the engine may be damaged by the impact of foreign objects. Among them, bird strikes are the most dangerous. The invention adopts a negative pressure launch mechanism, which can realize the negative pressure launch of the bird body in a vacuum state, and simulate the impact process of the bird on the aero-engine. The present invention can solve the problem that the current projectile velocity can only be tested from a relatively high speed. Since the present invention can realize negative pressure launch, the pressure of the high-pressure gas tank can be freely adjusted from negative pressure to positive pressure, and the projectile velocity can be adjusted freely. It can be controlled from low to high at will. Therefore, the different effects of projectile speed on the engine damage from low to high can be simulated, which provides an effective means for the anti-bird strike design of our country's engines, and is of great significance for improving our country's engine bird strike test technology and engine design level.

Description of drawings

Fig. 1 is the structural representation of the present invention;

Fig. 2 is the negative pressure emission schematic diagram of the emission state;

Figure 3 is a schematic diagram of the structure of the piston.

In the picture:

1. Launch valve; 2. First intake valve; 3. Piston sealing ring; 4. Control air chamber; 5. Piston; 6. Gun barrel; 7. Tee pipe; 8. Rear flange; 9. Front Flange plate; 10. Bird body; 11. Vacuum tank; 12. High pressure gas tank; 13. Air pump; 14. Second intake valve.

Detailed ways

Example 1

This embodiment is an air cannon negative pressure launching mechanism, including a vacuum tank 11, a control air chamber 4, a piston 5, an air pump 13 and a high-pressure air tank 12, all of which are in the prior art.

In this embodiment, the piston 5 is located in the control air chamber 4 . The control air chamber 4 is tubular and made of high-strength materials. The front flange 9 is installed on the end face of one end of the control air chamber, and the rear flange 8 is installed on the end face of the other end. The gun barrel 6 is installed in the center of the outer end face of the front flange; one end of the three-way pipe 7 connected to the vacuum tank 11 passes through the rear flange 8 and communicates with the control air chamber. The launch valve 1 is installed on the three-way pipe 7, and is located between the control air chamber and the vacuum tank. The high-pressure air tank 12 is located outside the control air chamber, and is connected to the control air chamber at 1/2 of the axial length of the control air chamber. The output end of the air pump 13 is respectively connected with the air inlet of the high-pressure air tank 12 and the three-way pipe 7 through pipelines, and the interface between the air pump and the three-way pipe 7 is located at the launch valve 1 and the control air chamber 4. between. A second intake valve 14 is installed on the pipeline between the air pump and the high-pressure air tank, and a first intake valve 2 is installed on the pipeline between the air pump and the three-way pipe.

In this embodiment, the piston 5 is composed of a piston rod, a pneumatic pushing plate at one end of the piston rod, and a support plate at the other end of the piston rod. The axial length of the piston is 2/3 of the axial length of the control air chamber; the axial length of the air pressure push plate is 1/6 of the axial length of the piston, and the axial length of the support plate is also 1/6 of the axial length of the piston. The diameter of the air pressure push plate and the diameter of the support plate are the same as the inner diameter of the control air chamber 4, and the air pressure push plate and the support plate are respectively slidably matched with the control air chamber.

There are 4 fan-shaped grooves symmetrically distributed on the circumference of the support plate, the radial depth of each fan-shaped groove is 1/6 of the diameter of the support plate, and the included angle between the two sides of each fan-shaped groove is 60°. The fan-shaped grooves form four fan-shaped cavities between the support plate and the inner wall of the control air chamber 4, and the cavities can ensure that the air pressure at both ends of the support plate is consistent. A piston sealing ring 3 made of rubber is embedded at the outer edge of the outer end face of the support plate; the inner diameter of the piston sealing ring is larger than the inner diameter of the gun barrel 6 and the outer diameter is smaller than that at the bottom of the fan-shaped groove on the support plate minimum diameter.

The diameter of the piston rod is 1/6 times the diameter of the control air chamber 4 . When installing the piston 5, the air pressure push plate is located at one end of the rear flange plate 8 of the control air chamber 4, and the control air chamber 4 is divided into a first air chamber and a second air chamber by the air pressure push plate, wherein the first air chamber. It is the air chamber between the air pressure pushing plate and the front flange plate 9, and the second air chamber is the air chamber between the rear flange plate 8 and the air pressure pushing plate, which is controlled by controlling the pressure of the first air chamber and the second air chamber. The piston 5 moves, and then controls the isolation and opening of the high-pressure gas tank 12 and the gun barrel 6 to realize the inflation and firing of the gas gun.

Before the start of the negative pressure bird strike experiment, the vacuum tank 11 and the gun barrel 6 are evacuated first. The fan-shaped groove 2 of the first intake valve controls the air pump 13 to input high-pressure air from one end of the rear flange 8 of the control air chamber 4 into the second air chamber, and the pressure of the high-pressure air is 1.5 times that of the emitted gas. After the high-pressure gas enters the second air chamber, the air pressure pushing end of the piston 5 moves toward the gun barrel 6 due to the pressure difference on both sides and touches the inner end face of the front flange 9, and the piston sealing ring 3 makes the first air chamber. It is isolated from the barrel 6 and is in a sealed state. After the second air chamber is inflated, the high-pressure air tank 12 and the first air chamber are inflated by the fan-shaped groove 14 of the second intake valve. In a sealed space, high-pressure air will be sealed in the first air chamber, so that the air pressure in the first air chamber is higher than the air pressure in the gun barrel 6 . After the first air chamber is inflated, the launch valve 1 is opened, and the high-pressure gas sealed in the second air chamber will enter the vacuum tank 11 through the three-way pipe 7, causing the air pressure of the second air chamber to drop suddenly. The first air chamber is still high-pressure gas. Due to the unbalanced force on the push end of the piston 5, the piston 5 moves to one end of the rear flange 8 under the action of the high air pressure of the first air chamber until it touches the rear flange. 8. The movement of the piston 5 makes the piston sealing ring 3 break away from the front flange 9, and the control air chamber 4 is communicated with the gun barrel 6, and the closed high-pressure air can enter the gun barrel 6 instantly from the first air chamber and the high-pressure air tank 12, The high-pressure gas will push the bird body 10 in the gun barrel 6 to accelerate to realize the bird strike test.

During the bird strike test, the speed of the bird body 10 is high and low. Since the gun barrel 6 is in a vacuum state, when a low-speed bird strike is required, the firing pressure of the air gun is 0. Since the pressure of the gun barrel 6 is a vacuum, the firing pressure at this time is 0. The speed is equivalent to the launch speed when the pressure of the high-pressure gas tank is 1 standard atmospheric pressure during the test in the atmospheric environment, even negative pressure. The existing gas cannon firing mechanism cannot work normally when the firing pressure is 0 or negative pressure. Therefore, the present invention connects a vacuum tank 11 to the firing valve 1 of the firing mechanism. When a vacuum low-speed impact is required, both the gun barrel 6 and the vacuum tank 11 are evacuated. At this time, according to the test requirements, the pressure of the gas chamber 4 and the high-pressure gas tank 12 is controlled to be 0 or negative pressure, and the launch valve 1 is opened when launching. The valve 1 is connected with a vacuum tank 11, the air in the control air chamber 4 and the high-pressure air tank 12 pushes the piston 5 to move towards the gun barrel, and the air in the high-pressure air tank 12 enters the gun barrel 6 to push the bird body 10 to launch.

Claims (3)

1. The utility model provides an air bubble negative pressure launching mechanism which characterized in that, includes vacuum tank, control air chamber, piston, air pump and high-pressure gas pitcher, wherein: the piston is positioned in the control air chamber; the control air chamber is divided into a first air chamber and a second air chamber; the end face of one end of the control air chamber is provided with a front flange plate, and the end face of the other end of the control air chamber is provided with a rear flange plate; the gun barrel is arranged in the center of the outer end face of the front flange plate; one end of a three-way pipe connected with the vacuum tank penetrates through the rear flange plate to be communicated with the control air chamber; the launching valve is arranged on the three-way pipe and is positioned between the control air chamber and the vacuum tank; the high-pressure gas tank is positioned outside the control gas chamber and is connected to the control gas chamber at the axial length 1/2 of the control gas chamber; the output end of the air pump is respectively communicated with the air inlet of the high-pressure air tank and the three-way pipe through pipelines, and the interface of the air pump and the three-way pipe is positioned between the emission valve and the control air chamber; a second air inlet valve is arranged on a pipeline between the air pump and the high-pressure air tank, and a first air inlet valve is arranged on a pipeline between the air pump and the three-way pipe;

the piston consists of a piston rod, an air pressure pushing disc positioned at one end of the piston rod and a supporting disc positioned at the other end of the piston rod; the axial length of the piston is 2/3 which controls the axial length of the chamber of the air chamber; the axial length of the pneumatic pushing disc is 1/6 of the axial length of the piston, and the axial length of the supporting disc is 1/6 of the axial length of the piston;

the diameter of the pneumatic pushing disc and the diameter of the supporting disc are both the same as the inner diameter of the control air chamber, and the pneumatic pushing disc and the supporting disc are respectively in sliding fit with the control air chamber;

four fan-shaped grooves are symmetrically distributed on the circumference of the supporting disc; a piston sealing ring is embedded at the outer edge of the outer end face of the supporting disc; the diameter of the piston rod is 1/6 times the diameter of the control air chamber.

2. The air cannon negative pressure launching mechanism of claim 1, wherein the radial depth of the sector groove on the circumference of the support plate is 1/6 degrees of the diameter of the support plate, and the included angle between the two side edges of each sector groove is 60 degrees.

3. The air cannon negative pressure launching mechanism of claim 1, wherein the first air chamber of the control air chamber is a cavity between the air pressure thrust plate and the front flange, and the second air chamber is a cavity between the rear flange and the air pressure thrust plate.

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