Step-shaped pool design method suitable for cone-head projectile body inclined water entry test

Abstract

The invention discloses a step-shaped pool design method suitable for a cone-head projectile body inclined water entry test, which comprises the following steps: selecting a plurality of typical water entry conditions to carry out projectile body water entry fluid-solid coupling numerical simulation calculation according to a projectile body water entry test speed range and an inclination angle range; according to the calculated underwater motion trail of the projectile body, converting the underwater motion trail into a motion trail under a global coordinate system; extracting the maximum horizontal displacement and the water entry depth of the projectile body under each water entry condition under the global coordinate system, and calculating to obtain the initial position coordinates of the corresponding step-shaped pool steps by combining with a certain margin; calculating the overall structure size of the whole pool according to the obtained initial position coordinates of each step; according to the ladder-shaped pool, the actual volume of the pool is reduced, so that the water injection time in the test is shortened, water in the whole pool does not need to be drained when the projectile body is recycled, and water only needs to be pumped to the corresponding steps where the projectile body moves; and the projectile body can be ensured not to collide with the wall surface of a pool in the water entering deflection process.

Description

Technical Field

[0001] The invention relates to the technical field of impact dynamics, and in particular to a stepped water pool design method suitable for a cone-head projectile inclined water entry test. Background Art

[0002] Projectile entering water is a common scenario in weapon design and service. Conducting projectile entry into water tests to examine the underwater trajectory and structural response of the projectile is a common test item in the projectile development process. The test conditions that are usually concerned in the inspection test include projectile velocity and inclination angle.

[0003] The common way to conduct a projectile entry test is to set up a projectile launch platform at the edge of the pool, set up high-speed photography and other shooting devices at the bottom or edge of the pool, fill the pool with water, launch the projectile into the pool through the launch platform, test the underwater motion trajectory and cavitation morphology of the projectile, and finally recover the projectile to detect the structural response of the projectile. In the process of recovering the projectile, in order to intuitively obtain the deformation and damage morphology of the projectile or the underwater photography device, the common treatment method is to drain the water and then recover the projectile. At present, the construction of the pool is mainly based on regular cylinders or cuboids. In order to adapt to the different speeds and different inclinations of the projectile entering the water, the size of the pool to be built is very large, resulting in a large waste of water resources, and the process of water injection and pumping takes a lot of time, which is not conducive to the implementation of multiple consecutive tests. In addition, due to the large depth of the pool, the effective viewing distance of the underwater lens is reduced, which has a certain impact on the clarity of the projectile motion trajectory shooting. And research shows that when the cone-head projectile tilts into the water, the underwater trajectory of the projectile is unstable and deflects toward the water surface.

[0004] According to the characteristics of projectile tests, it is necessary to develop a stepped water pool design method suitable for the test of cone-head projectiles entering water at different speeds and different inclination angles. Summary of the invention

[0005] The purpose of the present invention is to design a stepped water pool design method suitable for the inclined water entry test of a cone-head projectile in order to solve the above-mentioned problem.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions: A stepped water pool design method suitable for a cone-head projectile inclined water entry test comprises the following steps: S1: According to the velocity range and inclination angle range of the projectile entry test, several typical water entry conditions are selected to carry out fluid-solid coupling numerical simulation calculation of the projectile entry into water; S2: According to the calculated underwater motion trajectory of the projectile, convert it into the motion trajectory in the global coordinate system; S3: extract the maximum horizontal displacement and water entry depth of the projectile in the global coordinate system under each water entry condition, and calculate the starting position coordinates of the corresponding stepped pool steps with a certain margin; S4: Calculate the overall structural dimensions of the entire pool based on the obtained starting position coordinates of each step.

[0007] In step S1, typical water entry conditions include S11: Select the maximum value of the projectile entry test speed range as the calculated water entry speed; S12: selecting multiple inclination angle values ​​within the inclination angle range of the projectile entry test as the calculated water entry inclination angle. If the selected number is n, the number of steps in the corresponding designed stepped pool is also n, and the selected inclination angle includes the maximum value and the minimum value of the test inclination angle range; S13: Impact dynamics software is used to carry out flow-solid coupling calculation of the projectile entering water under different working conditions to obtain the underwater motion trajectory curve of the projectile.

[0008] Specifically, in step S2, the calculated underwater motion trajectory of the projectile is converted into a motion trajectory in the global coordinate system, including S21: The position where the projectile touches the water surface is taken as the origin of the local coordinate system of the projectile's underwater motion, and the trajectory of the projectile's underwater motion is ( x 1 , y 1 ); S22: Take the edge of the pool surface as the origin of the global coordinate system, and assume that the motion trajectory of the projectile in the global coordinate system is ( x , y ); S23: The transformation relationship between the local coordinate system and the global coordinate system is: ; In the formula H is the vertical height of the missile launch port from the water surface, θ is the initial inclination angle of the projectile entering the water.

[0009] Specifically, in step S3, the starting position coordinates of the corresponding stepped pool steps are calculated according to the maximum horizontal displacement and water entry depth of the projectile in the global coordinate system, including S31: Arrange the selected n inclination samples from large to small, recorded as θ 1 , θ 2 … θ n ; S32: Every entry angle θ i Under this condition, the maximum horizontal displacement of the projectile in the global coordinate system is extracted. x max and water depth y min , denoted as (x i , y i ); S33: Convert to get i The starting coordinates of the steps are , the corresponding conversion relationship is: ; in, h It is the distance between the maximum depth of the projectile entering the water and the step surface of the pool.

[0010] Specifically, in step S4, the overall structural dimensions of the pool are calculated by: S41: The total length of the pool is , the total depth range is , the value is obtained as follows: ; in , They represent the horizontal distance between the right edge of the pool and the nth step, and the vertical distance between the bottom of the pool and the first step respectively; S42: The total width of the pool is more than 10 times the diameter of the projectile; S43: As the i The horizontal range of the steps, As the i The vertical range of the steps constructs the stepped structure of the stepped pool.

[0011] The beneficial effects of the present invention are: (1) The present invention is based on the fluid-solid coupling numerical simulation calculation of the projectile entering the water process, which can predict the motion trajectory of the projectile entering the water process in advance. Combined with a certain margin design, it can ensure that the projectile does not collide with the wall of the pool during the deflection process of entering the water; (2) The maximum water entry velocity of the projectile and the typical inclination angles containing the extreme values ​​of the water entry inclination angle are selected to carry out fluid-structure coupling numerical simulation calculations, and the designed water pool size is sufficient for the water entry tests of the projectile at different velocities and different inclination angles; (3) The use of stepped water pools reduces the amount of earthwork excavation work during the construction of the water pool. The reduction in the actual volume of the water pool reduces the water filling time during the test. When recovering the projectile, there is no need to drain the water from the entire water pool. It only needs to be pumped to the corresponding steps where the projectile moves, which effectively shortens the test cycle. (4) Placing an underwater photography device on the steps of the stepped pool can more clearly capture the underwater motion trajectory of the projectile and the cavitation morphology, effectively improving the accuracy of the test results. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1It is a schematic diagram of the overall layout of the projectile incident water pool of the present invention; Figure 2 It is a schematic diagram of the projectile structure of the present invention; Figure 3 is a motion trajectory diagram of the projectile of the present invention in a local coordinate system; Figure 4 is a motion trajectory diagram of the projectile of the present invention in a global coordinate system; Figure 5 It is a structural diagram of the stepped pool described in the present invention. DETAILED DESCRIPTION

[0013] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0014] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0016] In the description of the present invention, it should be understood that the terms "upper", "lower", "inside", "outside", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use, or are directions or positional relationships commonly understood by those skilled in the art. These directions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0017] Furthermore, the terms “first”, “second”, etc. are merely used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0018] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms such as "setting" and "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0019] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings.

[0020] In the embodiment of the present invention, a typical cone-head projectile is used for analysis. The cylindrical diameter is 156 mm, the length is 280 mm, the short length of the cone is 370 mm, the material is steel, the mass is 26 kg, and the specific structure is as follows: Figure 2 As shown in the figure, it is clear that the speed range of the projectile entering the water test is 50 m / s ~500 m / s, and the inclination angle of the water entry test is 15°~75°. Figure 1 As shown, a launching platform is set up beside the pool, and a projectile launching tube is arranged on the launching platform for multi-angle launching of the projectile; the water level is flush with the horizontal plane, and the bottom of the launching platform is located on the horizontal plane.

[0021] The present invention is a step-shaped water pool design method suitable for a cone-head projectile inclined water entry test, comprising the following steps: S1: According to the velocity range and inclination angle range of the projectile entry test, several typical water entry conditions are selected to carry out fluid-solid coupling numerical simulation calculation of the projectile entry into water; Step S1 performs the following steps: S11: Select the maximum value of the projectile entry test speed range, i.e., 500 m / s, as the calculated water entry speed; S12: Select multiple inclination angles within the inclination angle range of the projectile entry test as the calculated water entry inclination angle. Assuming that the selected inclination angle number n is 5, the number of steps in the corresponding stepped pool is also 5. The selected inclination angle should include the maximum value of 75° and the minimum value of 15° in the test inclination angle range. The five water entry inclination angles selected in this embodiment are 15°, 30°, 45°, 60° and 75° respectively. S13: Using the impact dynamics software PANDA-IMPACT (or other commercial software) to perform fluid-solid coupling calculations of the projectile entering water under different working conditions, and obtain the underwater motion trajectory curve of the projectile; in this embodiment, the fluid-solid coupling numerical simulation calculations are performed for the projectile at a speed of 500 m / s and at water entry angles of 15°, 30°, 45°, 60° and 75°, respectively, and the underwater motion trajectory of the projectile under different working conditions is obtained as follows: Figure 3As shown, it can be seen that when the water entry angle decreases, the depth of the projectile moving underwater decreases, and when the water entry angle is 15°, the projectile will even move out of the water.

[0022] S2: According to the calculated underwater motion trajectory of the projectile, convert it into the motion trajectory in the global coordinate system; Step S2 includes the following steps: S21: The position where the projectile touches the water surface is taken as the origin of the local coordinate system of the projectile's underwater motion, and the trajectory of the projectile's underwater motion is ( x 1 , y 1 ), the corresponding motion trajectory curve is as follows Figure 3 As shown; S22: Take the edge of the pool surface as the origin of the global coordinate system, and assume that the motion trajectory of the projectile in the global coordinate system is ( x , y ); S23: The transformation relationship between the local coordinate system and the global coordinate system is: ; In the formula H is the vertical height of the missile launch port from the water surface, θ is the initial inclination angle of the projectile entering the water. H Take it as 5m, and convert the trajectory of the projectile in the global coordinate system into Figure 4 shown.

[0023] S3: extract the maximum horizontal displacement and water entry depth of the projectile in the global coordinate system under each water entry condition, and calculate the starting position coordinates of the corresponding stepped pool steps with a certain margin; Step S3 includes the following steps: S31: Arrange the selected n inclination samples from large to small, recorded as θ 1 , θ 2 … θ n ; This embodiment corresponds to θ 1 ~ θ 5 They are 75°, 60°, 45°, 30° and 15° respectively; S32: Every entry angle θ i Under this condition, the maximum horizontal displacement of the projectile in the global coordinate system is extracted. x max and water depth y min , denoted as ( xi , y i ); This embodiment extracts Figure 4 Each curve in x max and y min， They are (5.0, -5.0), (7.1, -3.2), (9.2, -2.2), (12.6, -0.9), (21.9, -0.3) respectively; S33: Convert to get i The starting coordinates of the steps are , the corresponding conversion relationship is: ; in, h The maximum depth of the projectile entering the water is set by humans, and the distance from the step surface of the pool ensures that the pool depth has a certain margin design based on the calculation. h If it is set to 1m, the starting coordinates of each step can be obtained as (5.0,-6.0), (7.1,-4.2), (9.2,-3.2), (12.6,-1.9), and (21.9,-1.3).

[0024] S4: Calculate the overall structural dimensions of the entire pool based on the obtained starting position coordinates of each step.

[0025] Step S4 includes the following steps: S41: The total length of the pool is , the total depth range is , the value is obtained as follows: ; in , Respectively represent the horizontal distance between the right edge of the pool and the nth step and the vertical distance between the bottom of the pool and the first step. , If both are taken as 0.5m, we can get: ; That is, the total length of the pool is 22.4m and the total depth is 6.5m.

[0026] S42: The total width of the pool does not need to be specially designed, and is taken as more than 10 times the diameter of the projectile based on engineering experience; in this embodiment, the total width of the pool is taken as 2m; S43: As the i The horizontal range of the steps, As the iThe vertical range of each step is used to construct the step structure of the stepped pool. According to this embodiment, the horizontal range of the first step in the global coordinate system is [5.0, 7.1], and the vertical range is [-6.5, -6.0]; the horizontal range of the second step is [7.1, 9.2], and the vertical range is [-6.0, -4.2]; the horizontal range of the third step is [9.2, 12.6], and the vertical range is [-4.2, -3.2]; the horizontal range of the fourth step is [12.6, 21.9], and the vertical range is [-3.2, -1.9]; the horizontal range of the fifth step is [21.9, 22.4], and the vertical range is [-1.9, -1.3].

[0027] The schematic diagram of the pool structure constructed in this way is as follows Figure 5 By comparison, it can be seen that if the design is based on the commonly used rectangular parallelepiped form, its length, width and depth are 22.4m, 2m and 6.5m respectively, and the water injection volume during the test is about 291m 3 .according to Figure 5 The stepped pool design has a water injection volume of approximately 166.2m 3 .

[0028] The above are only preferred embodiments of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for designing a stepped water pool suitable for a cone-head projectile inclined water entry test, characterized in that: The following steps are involved: S1: According to the velocity range and inclination angle range of the projectile entry test, several typical water entry conditions are selected to carry out fluid-solid coupling numerical simulation calculation of the projectile entry into water; S2: According to the calculated underwater motion trajectory of the projectile, convert it into the motion trajectory in the global coordinate system; S3: extract the maximum horizontal displacement and water entry depth of the projectile in the global coordinate system under each water entry condition, and calculate the starting position coordinates of the corresponding stepped pool steps with a certain margin; S4: Calculate the overall structural dimensions of the entire pool based on the obtained starting position coordinates of each step.

2. A method for designing a stepped water pool suitable for a cone-head projectile inclined water entry test according to claim 1, characterized in that: In step S1, typical water entry conditions include S11: Select the maximum value of the projectile entry test speed range as the calculated water entry speed; S12: selecting multiple inclination angle values ​​within the inclination angle range of the projectile entry test as the calculated water entry inclination angle. If the selected number is n, the number of steps in the corresponding designed stepped pool is also n, and the selected inclination angle includes the maximum value and the minimum value of the test inclination angle range; S13: Impact dynamics software is used to carry out flow-solid coupling calculation of the projectile entering water under different working conditions to obtain the underwater motion trajectory curve of the projectile.

3. The method for designing a stepped water pool suitable for a cone-head projectile inclined water entry test according to claim 1, characterized in that: In step S2, the calculated underwater motion trajectory of the projectile is converted into a motion trajectory in the global coordinate system, including S21: The position where the projectile touches the water surface is taken as the origin of the local coordinate system of the projectile's underwater motion, and the trajectory of the projectile's underwater motion is ( x 1, y 1); S22: Take the edge of the pool surface as the origin of the global coordinate system, and assume that the motion trajectory of the projectile in the global coordinate system is ( x , y ); S23: The transformation relationship between the local coordinate system and the global coordinate system is: ； In the formula H is the vertical height of the missile launch port from the water surface, θ is the initial inclination angle of the projectile entering the water.

4. The method for designing a stepped water pool suitable for a cone-head projectile inclined water entry test according to claim 1, characterized in that: In step S3, the starting position coordinates of the corresponding stepped pool steps are calculated according to the maximum horizontal displacement and water entry depth of the projectile in the global coordinate system, including S31: Arrange the selected n inclination samples from large to small, recorded as θ 1. θ 2… θ n ; S32: Every entry angle θ i Under this condition, the maximum horizontal displacement of the projectile in the global coordinate system is extracted. x max and water depth y min , denoted as ( x i , y i ); S33: Convert to get i The starting coordinates of the steps are , the corresponding conversion relationship is: ； in, h It is the distance between the maximum depth of the projectile entering the water and the step surface of the pool.

5. The method for designing a stepped water pool suitable for a cone-head projectile inclined water entry test according to claim 1, characterized in that: In step S4, the overall structural dimensions of the pool are calculated by a method including: S41: The total length of the pool is , the total depth range is , the value is obtained as follows: ； in , They represent the horizontal distance between the right edge of the pool and the nth step, and the vertical distance between the bottom of the pool and the first step respectively; S42: The total width of the pool is more than 10 times the diameter of the projectile; S43: As the i The horizontal range of the steps, As the i The vertical range of the steps constructs the stepped structure of the stepped pool.

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