Light gas gun cone segment inner flow channel structure

Abstract

The application relates to a light gas gun cone segment inner flow channel structure and belongs to the field of laboratory super-high-speed launching devices. In the existing commonly-used cone segment inner flow channel structure, a conical transition surface is formed through linear transition between an inlet segment and an outlet segment. Under the structure, high-pressure gas internal energy loss is large, the impact force of a piston on the cone segment is large, and the kinetic energy conversion efficiency transferred to a projectile is low. In the application, the inner flow channel shape of the light gas gun cone segment is designed, the original linear transition mode is changed into a cosine curve transition mode, the conversion efficiency of high-pressure gas internal energy to projectile kinetic energy is effectively improved, and the impact effect generated by the piston entering the cone is reduced. In the application, the connection point of the cosine curve and the inlet segment is recorded as a starting point C, the tangent slope of the C point is 0, the connection point of the cosine curve and the outlet segment is recorded as an ending point E, the tangent slope of the E point is 0, and the tangent slope of the cosine curve gradually changes from 0 to -1 and then to 0 from the starting point C to the ending point E.

Description

Technical Field

[0001] This invention belongs to the field of laboratory ultra-high-speed launch devices, specifically relating to the internal flow channel structure of a light gas cannon cone section. Background Technology

[0002] Light gas cannons are one of the most widely used technologies in the field of laboratory hypersonic launch devices, playing a crucial role in simulating fragment damage elements, analyzing the damage effects of fragments and other projectiles on targets, and protecting against space debris. Currently, light gas cannons are classified into single-stage, two-stage, and multi-stage types. Taking a gunpowder-driven two-stage light gas cannon as an example, its structural diagram is shown below. Figure 1 (Reference: Jiao Dezhi, Huang Jie, Ping Xinhong, Zou Shengyu, Liang Shichang, Liu Sen. Chinese Congress of Theoretical and Applied Mechanics, 2017). Figure 1 In this configuration, 1 is the combustion chamber, 2 is the compression tube, 3 is the conical section (high-pressure section), 4 is the launch tube, 5 is the large diaphragm, 6 is the piston, 7 is the small diaphragm, and 8 is the projectile. The combustion chamber, compression tube, conical section, and launch tube are coaxially and fixedly connected in sequence, forming an internal airflow channel. The large diaphragm is located at the junction of the combustion chamber and the compression tube, the piston is located inside the compression tube, the small diaphragm is located at the inlet end of the launch tube, and the projectile is located inside the launch tube. When the light gas gun is working, the gunpowder in the combustion chamber burns to produce high-temperature and high-pressure gas. When the high-pressure gas reaches a certain pressure, it causes the large diaphragm to rupture, pushing the piston in the compression tube to move at high speed. During the piston's movement, it compresses the light gas (usually hydrogen or helium) in the compression tube. When the pressure reaches a certain value, the small diaphragm ruptures, pushing the projectile in the launch tube to move at high speed, thus achieving ultra-high-speed launch of the projectile.

[0003] In existing lightweight gas cannon structures, the internal flow channel shape of the cone section is generally as follows: Figure 2 The illustrated conical structure has a conical transition surface formed by a straight line between the gas inlet and outlet. In this structure, the gas loses a significant amount of internal energy as it passes through the inner wall of the conical section. This results in a reduced thrust on the projectile after the diaphragm ruptures, affecting the projectile's launch velocity. Furthermore, the piston enters the conical section at high speed, and the conical transition surface structure causes a significant impact from the piston, leading to substantial kinetic energy loss. According to the law of conservation of energy, this also affects the thrust of the gas on the projectile.

[0004] Therefore, it is necessary to improve the flow channel shape within the cone section. Summary of the Invention

[0005] The technical problem to be solved:

[0006] To overcome the shortcomings of existing technologies, this invention provides an internal flow channel structure for the conical section of a light gas cannon. The design focuses on the shape and structure of the internal flow channel in the conical section of two-stage and multi-stage light gas cannon devices. By analyzing the process from the piston's initial movement to the rupture of the small diaphragm, which then propels the projectile at high speed, the existing straight conical transition inner wall of the conical section's internal flow channel is designed as a curved transition inner wall. This improves the conversion efficiency of the high-pressure gas's internal energy into the projectile's kinetic energy and reduces the impact force generated by the piston striking the conical section when it enters the cone.

[0007] The technical solution of this invention is: an internal flow channel structure for a light gas cannon cone section, wherein the internal flow channel penetrates the cone section along its axis to form a gas flow channel; the internal flow channel consists of an inlet section, a transition section, and an outlet section in sequence along the airflow direction; both the inlet section and the outlet section are circular straight hole structures, with the diameter of the inlet section being larger than that of the outlet section; the transition section connects the inlet section and the outlet section; the transition section is a non-uniform diameter curved surface internal hole structure, and the curved surface is a curve in the cross-section along the axis of the internal flow channel; the connection point between the curve and the inlet section is denoted as the starting point C, and the tangent slope at point C is 0; the connection point between the curve and the outlet section is denoted as the ending point E, and the tangent slope at point E is 0; the tangent slope of the curve changes from 0 to -1 and then back to 0 from the starting point C to the ending point E.

[0008] A further technical solution of the present invention is that the curve is one of a cosine curve, a sine curve, or a hyperbola.

[0009] A further technical solution of the present invention is: the point where the slope of the tangent of the curve is -1 is marked as point O, and the position of point O is located between the middle of the transition section and the exit section.

[0010] A further technical solution of the present invention is: the inlet section of the inner flow channel is connected to the compression pipe of the light gas gun, and the diameter of the inlet section is the same as the inner diameter of the compression pipe.

[0011] A further technical solution of the present invention is: the outlet section of the inner flow channel is connected to the firing tube of the light air gun, and the diameter of the outlet section is the same as the inner diameter of the firing tube.

[0012] A further technical solution of the present invention is that the internal flow channel structure is suitable for the conical section in a two-stage or multi-stage light air gun device.

[0013] Beneficial effects

[0014] The beneficial effects of this invention are as follows: The internal flow channel structure of the light air cannon cone section described in this invention improves the transition from a straight line to a curved line from the inlet to the outlet section of the cone section. The slope of the tangent from the starting point to the end point of the curve gradually changes from 0 to -1, and then from -1 back to 0, thereby forming an airflow buffer surface. (See reference...) Figure 3 The beneficial effects of this invention are mainly reflected in:

[0015] (1) When the piston compresses the gas in the compression tube at high speed, the gas enters the conical section from the inlet section and the pressure rises rapidly. The compression wave and gas movement generated when the gas is compressed into the conical section first act on the CO section. At this time, the CO section is relatively flat. After the compression wave is reflected, it converges towards the axis C'E' of the transition section. The component of the force generated by the gas movement along the radial direction is small, thereby reducing the internal energy dissipation of the gas through the inner wall of the conical section.

[0016] (2) When the small diaphragm at the inlet of the launch tube breaks, the high-pressure gas acts on the projectile inside the launch tube after passing through the outlet section of the conical section, pushing the projectile to accelerate. The curved surface of the OE section of the inner channel is similar to a "nozzle", which can effectively increase the speed of the high-pressure gas when passing through the cross section EE', increase the acceleration of the projectile, and thus increase the launch speed of the projectile to a certain extent.

[0017] (3) After the piston in the compression tube moves at high speed, it will enter the conical section and undergo a certain deformation at the transition section of the inner flow channel. When the piston first enters the conical section, the speed is high. After interacting with the curved surface of the CO section, it deforms. Since the CO section is a gradually changing curved surface, the piston deformation is slow at first and then fast. Since the resistance is generally proportional to the square of the speed, this makes the piston enter the cone more smoothly. Compared with the traditional conical section structure, the impact force is smaller, the piston's kinetic energy loss is smaller, and the internal energy consumption is reduced. The effect is better when the diameter difference between the inlet section and the outlet section is large, i.e., when the cone angle is large.

[0018] (4) In this invention, the slope of the tangent in the CO segment gradually changes from 0 to -1 and the slope of the tangent in the OE segment gradually changes from -1 to 0. The degree of change depends on the characteristic parameters such as the diameter of the CC' and EE' sections, the gas pressure in the cone section, and the piston speed, which makes it widely adaptable.

[0019] To demonstrate the advantages of the curved cone section internal flow channel structure of the present invention compared with the existing straight cone section internal flow channel structure, see [reference needed]. Figure 4 Finite element analysis models of the piston entering the cone within the flow channel structure of both the existing straight conical segment and the curved conical segment of this invention were established. The conical segments were both designed as rigid bodies, and the pistons as elastic bodies. The materials and other properties of both pistons were identical, and the initial velocity of the pistons was 300 m / s. The acceleration during the piston entering the cone was compared and analyzed: see [reference needed]. Figure 5 By comparing the time-domain acceleration curves along the piston's motion direction during the piston's cone entry process, it can be found that the peak acceleration of the curved cone section of the present invention is about 8.7% smaller than that of the straight cone section of the existing structure, proving that the piston's cone entry force on the entire light gas gun is smaller under the curved cone section structure. A comparative analysis of the total energy (sum of kinetic and potential energy) during the piston's cone entry process is provided: [See...] Figure 6 By comparing the time-domain curves of the total energy during the piston's entry into the cone, it can be found that the initial total energy of the piston is 1.1 × 10⁻⁶. 5 J, the total stable energy of the piston in the existing straight conical section is 8.21 × 10⁻⁶.4 J, the total piston stabilization energy of the curved conical section of this invention is 8.74 × 10⁻⁶. 4 J. Due to the neglect of the effect of high-pressure gas, the total piston energy reduction in the curved conical section is 0.53 × 10⁻⁶ less than that in the straight conical section. 4 J, this portion of energy can be more effectively converted into high-pressure gas energy. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of an existing two-stage light air gun structure;

[0021] Figure 2 This is a schematic diagram of the axial cross-section of the existing conical section internal flow channel structure;

[0022] Figure 3 This is a schematic cross-sectional view of the internal flow channel structure of the conical section of the present invention.

[0023] Figure 4 The figures show a comparison of finite element simulation analysis of the existing conical internal flow channel structure and the conical internal flow channel structure of the present invention during the piston entry process. In the figures: (a), (c), (e), (g), (i), and (k) represent the states of the existing straight conical internal flow channel structure at 0ms, 0.04ms, 0.08ms, 0.12ms, 0.16ms, and 0.2ms during piston entry, respectively; (b), (d), (f), (h), (j), and (l) represent the states of the curved conical internal flow channel structure of the present invention at 0ms, 0.04ms, 0.08ms, 0.12ms, 0.16ms, and 0.2ms during piston entry, respectively.

[0024] Figure 5 The figure shows a comparison of the time-domain acceleration curves along the piston movement direction during the piston entry process in the existing conical internal flow channel structure and the conical internal flow channel structure of the present invention. In the figure: (m) is the time-domain acceleration curve of the piston entering the cone in the existing straight conical internal flow channel structure, with a peak value of -6.31×10. 5 m / s 2 (n) is the time-domain curve of the piston inlet cone acceleration of the flow channel structure in the curved cone section of this invention, with a peak value of -5.76 × 10⁻⁶. 5 m / s 2 ;

[0025] Figure 6 The figures show a time-domain comparison of the total energy during piston entry into the cone in the existing conical internal flow channel structure and the conical internal flow channel structure of the present invention. In the figures: (o) is the time-domain curve of the total energy during piston entry into the cone in the existing straight conical internal flow channel structure, with an initial value of 1.1 × 10⁻⁶. 5 J, stable value after entering the cone: 8.21 × 10⁻⁶ 4 J; (p) is the time-domain curve of the total energy during the piston entry process of the flow channel structure in the curved conical section of the present invention, with an initial value of 1.1 × 10⁻⁶.5 J, stable value after entering the cone: 8.74 × 10 4 J.

[0026] Explanation of reference numerals in the attached figures: 1. Combustion chamber; 2. Compression tube; 3. Conical section; 31. Inlet section; 32. Transition section; 33. Outlet section; 4. Launch tube; 5. Large diaphragm; 6. Piston; 7. Small diaphragm; 8. Projectile; C. Starting point of the curve in the axial section of the transition section; O. Point with a tangent slope of -1 in the axial section of the transition section; E. Ending point of the curve in the axial section of the transition section; C'. Projection point of point C onto the inner flow channel axis; E'. Projection point of point E onto the inner flow channel axis. Detailed Implementation

[0027] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0028] In the description of this 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," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] Figure 1-2 In existing commonly used conical internal flow channel structures, the inlet section and outlet section form a conical transition surface through a straight transition (see...). Figure 2 In the internal flow channel structure, the centerline segment AB of the axial section shows significant energy loss in the high-pressure gas, resulting in a large impact force between the piston 6 and the cone segment 3, and low kinetic energy conversion efficiency to the projectile 8. Therefore, this invention improves the straight-cone transition surface structure in the internal flow channel, changing the original linear transition to a cosine curve transition, effectively improving the conversion efficiency of high-pressure gas internal energy to projectile 8's kinetic energy and reducing the impact effect generated by the piston 6 entering the cone. The internal flow channel structure designed in this invention only changes the shape of the internal flow channel in the cone segment 3, without altering the overall structure of the gas gun, making it highly feasible.

[0030] See Figure 3The internal flow channel structure of the light gas cannon cone section of the present invention comprises an internal flow channel, which is a through hole arranged along the axis of the cone section 3, forming a gas flow channel. The internal flow channel is coaxial with the cone section 3. The internal flow channel consists of an inlet section 31, a transition section 32, and an outlet section 33 in sequence along the airflow direction. The inlet section 31 and the outlet section 33 are both equal-diameter circular holes, with the diameter of the inlet section 31 being larger than the diameter of the outlet section 33. The transition section 32 is a curved surface that connects the inlet section 31 and the outlet section 33. Specifically, the transition section is a non-equal-diameter curved surface internal hole structure. This curved surface is a curve COE in the cross-section along the axis of the internal flow channel. In this embodiment, the curve COE is a cosine curve, but it can also be extended to other cross-sectional gradient curves, such as sine curves and hyperbolas, based on characteristic parameters such as the piston speed 6, the cross-sectional dimensions of the inlet section 31 and the outlet section 33, and the length of the cone section 3. The connection point between the curve and the inlet section 31 is denoted as the starting point C, where the slope of the tangent line is 0. The connection point between the curve and the outlet section is denoted as the ending point E, where the slope of the tangent line is 0. The slope of the tangent line of this curve gradually changes from 0 at the starting point C to -1 and then gradually changes back to 0 from the ending point E. The point where the slope of the tangent line of the curve is -1 is denoted as point O, located between the middle of the axial direction of the transition section 32 and the outlet section 33. The vertical projection of point C onto the inner flow channel axis is denoted as C', and the vertical projection of point E onto the inner flow channel axis is denoted as E'. Figure 3 The transition surface of transition segment 32 is formed by rotating the middle curve COE around the axis C'E' for one revolution.

[0031] The inlet section 31 of the inner flow channel is connected to the compression tube 2 of the light gas cannon, and the diameter of the inlet section 31 is the same as the inner diameter of the compression tube 2. The outlet section 33 of the inner flow channel is connected to the firing tube 4 of the light gas cannon, and the diameter of the outlet section 33 is the same as the inner diameter of the firing tube 4. In another embodiment of the present invention, in order to simplify the inner flow channel structure of the conical section 3, the axial dimensions of the inlet section 31 and the outlet section 33 are both zero, that is, the CC' section of the transition section 32 is directly connected to the compression tube 2, and the EE' section of the transition section 32 is directly connected to the firing tube 4.

[0032] The internal flow channel structure in this invention is suitable for the conical section in two-stage and multi-stage light air cannon devices. It does not require altering the overall structure of the light air cannon; simply changing the shape of the internal flow channel within the conical section increases the airflow velocity, reduces the impact force of the piston 6 on the conical section 3, and improves the kinetic energy conversion efficiency of the projectile 8. In existing light air cannon devices, the diameter of the conical inlet section 31 is 155mm or 203mm, the diameter of the outlet section 33 is 10mm or 16mm, and the length of the conical section varies. This invention can design the internal flow channel structure dimensions according to the specific specifications of the light air cannon. It only requires ensuring that the slope of the tangent of the cosine curve COE in the transition section 32 gradually changes from 0 at the starting point C to -1 and then back to 0 at the ending point E. Point O is located at the axial midpoint of the transition section 32, or between the midpoint of the transition section 32 and the outlet section 33.

[0033] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. An internal flow channel structure for a light gas cannon cone section, wherein the internal flow channel extends along the axis of the cone section (3) to form a gas flow channel, and the internal flow channel is sequentially composed of an inlet section (31), a transition section (32), and an outlet section (33) along the airflow direction; the inlet section (31) and the outlet section (33) are both circular straight hole structures, and the diameter of the inlet section (31) is larger than the diameter of the outlet section (33); the transition section (32) connects the inlet section (31) and the outlet section (33), characterized in that: The transition section (32) is a non-equal diameter curved surface internal hole structure. The curved surface is a curve in the cross section along the axis of the inner flow channel. The connection point between the curve and the inlet section (31) is denoted as the starting point C. The tangent slope at point C is 0. The connection point between the curve and the outlet section (33) is denoted as the ending point E. The tangent slope at point E is 0. The tangent slope of the curve changes from 0 to -1 and then back to 0 from the starting point C to the ending point E. The curve is either a cosine curve or a sine curve; the point where the tangent slope of the curve is -1 is marked as point O, and the position of point O is between the middle of the axial direction of the transition section (32) and the outlet section (33); the vertical projection point of point C on the inner channel axis is marked as C', and the vertical projection point of point E on the inner channel axis is marked as E'. The curve COE rotates around the axis C'E' for one revolution to form the transition surface of the transition section (32); The inlet section (31) of the inner flow channel is connected to the compression tube (2) of the light air gun, and the diameter of the inlet section (31) is the same as the inner diameter of the compression tube (2); the outlet section (33) of the inner flow channel is connected to the firing tube (4) of the light air gun, and the diameter of the outlet section (33) is the same as the inner diameter of the firing tube (4); the inner flow channel structure is suitable for the conical section (3) in a multi-stage light air gun device.

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