Natural lightning leaded ship lightning attachment point prediction method

Abstract

The invention relates to the technical field of ship thunder and lightning protection effect verification and evaluation, in particular to a natural thunder and lightning pilot ship thunder and lightning attachment point prediction method. According to the method, the ship scale model lightning attachment test simulating natural lightning pilot is carried out, so that the areas, positions and times of lightning attachment or breakdown of a ship deck, equipment and parts on the deck and the like can be counted, and the lightning attachment probability of the ship surface equipment can be accurately predicted; and meanwhile, according to the prediction result, the natural lightning leading lightning attachment area is divided, effective support can be provided for lightning protection of equipment and parts in each lightning subarea of the ship, and the method has important significance for ship lightning protection design and evaluation of lightning risk of key parts of the ship and lightning rod protection effect.

Description

Technical Field

[0001] The present invention relates to the technical field of ship lightning protection effect verification and evaluation, and in particular to a method for predicting ship lightning attachment points of natural lightning leaders. Background Art

[0002] Lightning is a natural phenomenon of ultra-long gap discharge, with the characteristics of high voltage amplitude, high current intensity, and strong destructive power. The ocean is an area where lightning is extremely likely to form. Ships sailing on the vast sea, their towering masts and various shipborne antennas and other protruding structures are targets that are easily attacked by lightning on the sea. Once a ship is struck by lightning, it is easy to cause damage to the ship's sensitive devices, equipment and systems, affecting navigation safety and mission execution. Therefore, it is necessary to carry out ship lightning protection design and evaluate the lightning strike risk of key parts of the ship and the protection effect of lightning rods.

[0003] At present, the method of direct lightning protection for ships is mostly to install lightning rods, and their protection range is generally determined by the "rolling ball method". However, the development process of lightning leaders and the attachment targets are random, and it is difficult to directly obtain the probability distribution of lightning attachment in different parts of the ship through theoretical analysis. In the existing marine regulations, the relevant provisions on how to determine the protection area of ​​the lightning rod and the height of the lightning rod on the metal hull are not sufficient. Therefore, it is necessary to carry out ship lightning attachment point tests, which are of great significance for supporting lightning protection design, evaluating the lightning risk of key parts of the ship and the protection effect of lightning rods. Summary of the invention

[0004] The technical problem to be solved by the present invention is: to propose a method for predicting the lightning attachment point of a ship with a natural lightning leader. By conducting a lightning attachment test on a scaled model of a ship simulating a natural lightning leader, the area, position and number of times that the ship deck and various equipment and components on the deck are attached or penetrated by lightning can be statistically analyzed, which can greatly improve the efficiency of ship lightning protection design.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A method for predicting ship lightning attachment points of natural lightning leaders mainly includes:

[0007] S1, natural lightning leader simulation: rod-shaped electrodes are selected to simulate the natural lightning downward leader;

[0008] S2, making test pieces: using conductive metal materials to make a scaled model of a ship, and using a metal plate of preset thickness to simulate the seawater equivalent plane;

[0009] S3, model partitioning and test electrode arrangement: the ship scale model is divided into n transverse test areas along the horizontal direction, and each transverse test area is divided into m longitudinal test areas along the end surface, and then the rod-shaped electrode is arranged just above the center of each test area;

[0010] S4, test arrangement: an impulse voltage generator is connected to the rod-shaped electrode to generate a lightning simulation leader, a digital storage oscilloscope is used to record the discharge polarity, voltage amplitude and waveform, and an optical camera is used to record the discharge arc path and attachment point;

[0011] S5, test waveform: the amplitude of the test waveform is determined according to whether the gap between the test piece and the rod-shaped electrode is broken down or flashed over the test piece;

[0012] S6, determining the test steps: completing the simulation test of all electrode positions according to the preset test steps;

[0013] S7, test record and data analysis: record the test data and conduct statistical analysis to obtain the locations where lightning is attached or penetrated in various areas of the ship under the guidance of natural lightning and the corresponding probability of lightning attachment at each location.

[0014] Furthermore, the scaled-down model of the ship includes a hull, a cabin, a lightning rod, an antenna tower, and a shortwave antenna. The scaling ratio of the scaled-down model of the ship is 1 / 20, and the closest distance between the rod-shaped electrode and the surface of the scaled-down model of the ship is 1.5 m.

[0015] Further, in step S3, the scaled ship model is first divided into 11 horizontal test areas along the horizontal direction, specifically: area 1, area + 1, area 2, area + 2, area 3, area + 3, area 4, area + 4, area 5, area + 5, area 6;

[0016] Each transverse test area is then divided into seven longitudinal test areas along the end surface, namely: area A, area B, area C, area D, area E, area F, and area G.

[0017] Furthermore, the rod-shaped electrodes are arranged in different test areas to simulate directions in which lightning leaders may enter when the ship is sailing in different postures.

[0018] Furthermore, in step S4, the high voltage end of the impulse voltage generator is connected to the rod-shaped electrode, the scaled ship model is placed on a grounded metal plate simulating a seawater equivalent plane, and the ground end of the impulse voltage generator is directly connected to the grounded metal plate.

[0019] Furthermore, the output voltage of the impulse voltage generator is sent to an oscilloscope via a coaxial cable after passing through a voltage divider to record the discharge polarity, voltage amplitude and waveform of the rod-shaped electrode.

[0020] Furthermore, in step S5, a 50% breakdown voltage of 1.2 times the gap is applied to ensure that the gap can be broken down in each test.

[0021] Further, in step S6, the test step includes:

[0022] 1) Measurement test environmental conditions: The environmental conditions include temperature, humidity, and atmospheric pressure;

[0023] 2) Check the test equipment and implement safety procedures: Before charging the test equipment, personnel must be evacuated, and before personnel re-enter the test area, the capacitor bank of the impulse voltage generator must be grounded;

[0024] 3) Select the initial electrode and complete the experimental equipment layout;

[0025] 4) Calibrate impulse voltage generators and measuring instruments;

[0026] 5) Keep the scaled model of the ship in the same position and conduct shock discharge on the model. Immediately after the discharge, check the photos taken by the optical camera to ensure that the attachment point of the arc on the model can be clearly identified in the photos;

[0027] 6) Apply a set of discharge tests to the model;

[0028] 7) Adjust the model posture and electrode position;

[0029] 8) Repeat steps 1) to 7) until all electrode positions have completed the test.

[0030] Furthermore, in step S7, the recording of test data includes: recording the electrode position, discharge times, polarity, discharge voltage, waveform number of each test, and recording the coordinates of each lightning attachment point.

[0031] Furthermore, by counting the lightning attachment positions on the scaled-down model of the ship in each test, the probability of each area of ​​the ship being struck by lightning under the guidance of natural lightning was obtained.

[0032] Compared with the prior art, the present invention has the following main advantages:

[0033] The present invention proposes a method for predicting the lightning attachment point of a ship with a natural lightning leader. By conducting a lightning attachment test on a scaled model of a ship simulating a natural lightning leader, the area, position and number of times that the ship deck and various equipment and components on the deck are attached or penetrated by lightning can be counted, thereby accurately predicting the probability of lightning attachment to the ship deck equipment.

[0034] At the same time, dividing the lightning attachment area of ​​the natural lightning leader according to the prediction results can provide effective support for the lightning protection of equipment and components in each lightning zone of the ship. It is of great significance for the ship's lightning protection design, evaluating the lightning strike risk of key parts of the ship and the protection effect of lightning rods. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the configuration of a test for simulating a natural lightning leader in an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of a scaled-down model of a ship in an embodiment of the present invention;

[0037] Figure 3 A top view of a ship lightning strike zone for simulating a natural lightning leader test in an embodiment of the present invention;

[0038] Figure 4 It is a side view of a ship lightning strike zone for simulating a natural lightning leader test in an embodiment of the present invention;

[0039] Figure 5 This is an end view of a ship lightning strike partition for simulating a natural lightning leader test in an embodiment of the present invention;

[0040] Figure 6 This is a schematic diagram of the arrangement of rod-shaped high-voltage electrodes for simulating a natural lightning leader test in an embodiment of the present invention;

[0041] Figure 7 It is a schematic diagram of the projection of the rod-shaped high-voltage electrode on the plane of the ship model and the corresponding numbers in an embodiment of the present invention;

[0042] Figure 8 Schematic diagram of arrangement relationship of seven electrode orientations in the xz plane in an embodiment of the present invention;

[0043] Fig. 9 A schematic diagram of test wiring and arrangement for simulating a natural lightning leader test in an embodiment of the present invention;

[0044] Fig.10 This is a voltage waveform diagram of breakdown within 2μs±1μs in an embodiment of the present invention;

[0045] Fig.11 It is the number of the lightning attachment position of the ship model in the embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0047] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0048] Embodiment 1: This embodiment provides a method for predicting the attachment point of ship lightning with a natural lightning leader, which is as follows:

[0049] 1. Natural lightning leader simulation

[0050] Thunderstorms usually occur when there are strong moist warm air currents. The cloud base height is generally 1 to 3 km, with the lowest reaching 150 m and the highest reaching more than ten kilometers. The average height of its main negative charge center is about 3 km.

[0051] The electrical geometry model assumes that before a thundercloud flashes to the ground (or a building), the leader that develops from the thundercloud to the ground must reach a certain range from the lightning strike point. It is generally believed that only when the thundercloud develops to a distance of several hundred meters from the struck object can the tall objects on the ground affect the development of the discharge channel. The distance between the leader point and the strike point is called the strike distance, which is the final stage of the leader development. The position of the leader head is irrelevant to the lightning strike object when it is greater than the strike distance. According to the test requirements, the distance of the lightning leader to the ground should be greater than the strike distance under the corresponding lightning current.

[0052] Model test is an effective method to determine the attachment point of lightning leader. In this test, rod-shaped electrodes are used to simulate the natural lightning leader. The typical test configuration is shown in Figure 1 The test simulates the direction in which the lightning leader may enter during the ship's voyage, and this is achieved by adjusting the model's posture and changing the electrode position.

[0053] According to NFPA 780, the lightning protection for ships adopts a strike distance of 30m. Based on the scale of 1 / 20, the distance between the high-voltage electrode and the nearest surface of the ship model is 1.5m.

[0054] 2. Test piece

[0055] The test piece is a scaled-down model of the original ship's external structure, and the outer surface of the test model is a conductive metal structure. The full metal ship model is made of metal sheets, and the metal parts such as the hull, cabin, lightning rod, antenna tower, shortwave antenna, etc. are consistent with the ship's external space structure, conductor material and electric field layout. The scaled-down model has a scale ratio of 1 / 20, and the corresponding length, width and height of the model are approximately 8.9m, 0.9m and 1.9m respectively. See the scaled-down model example diagram Figure 2 .

[0056] A metal aluminum plate with a thickness of 1 mm is used to simulate the seawater equivalent plane, and its length and width are 13 m and 3 m respectively.

[0057] 3. Model partition and test electrode arrangement

[0058] Considering the possible direction of the lightning leader, the position of the high-voltage electrode is changed to simulate the direction in which the lightning leader may enter when the ship is sailing in different postures. Figure 3 Each area is divided into A, B, C, D, E, F, G, see Figure 5 In areas 1, 2, 3, 4, 5, 6, +1, +2, +3, +4, and +5, the G area of ​​the ship is symmetrical with the B area, the F area is symmetrical with the C area, and the E area is symmetrical with the D area. Lightning attachment tests are carried out in areas A, B, C, and D. In area 3, the two sides of the ship are asymmetrical, and lightning attachment tests are carried out in all areas A, B, C, D, E, F, and G. Therefore, there are 47 test areas in total, such as 1A, 3E, 4D, etc.

[0059] Rod-shaped high-voltage electrodes are arranged directly above the center of each area. Figure 6 Arrange the positions of 27 types of rod-shaped high-voltage electrodes. Figure 7 for Figure 6 The projection diagram of the arrangement of medium and high voltage electrodes on the plane of the ship model and the relationship between their positions are shown in Figure 8 .

[0060] 4. Experimental arrangement

[0061] An impulse voltage generator is used to generate a lightning simulation leader, a digital storage oscilloscope is used to record the discharge polarity, voltage amplitude and waveform, and an optical camera is used to record the discharge arc path and attachment point.

[0062] The test wiring and layout diagram for the simulated natural lightning leader test is shown in Fig. 9 The high-voltage electrode is connected to the high-voltage end of the impulse voltage generator. The ship model is placed on a grounded metal plate simulating the equivalent plane of seawater, and the return line of the impulse voltage generator is connected to the grounded metal plate. The output voltage of the impulse voltage generator is sent to the oscilloscope through a coaxial cable after passing through a voltage divider for measurement. Two still cameras with adjustable exposure time are used to distinguish the attachment point positions on the model at different angles.

[0063] 5. Test waveform

[0064] The test for simulating naturally occurring lightning leaders uses the voltage waveform of the gap between the test piece and the electrode that breaks down within 2μs±1μs, see Fig.10 The amplitude of the test waveform is determined by the breakdown of the test piece or the flashover sliding over the test piece, and a 50% breakdown voltage of 1.2 times the gap is applied to ensure that the gap can be broken down in each test.

[0065] 6. Determine the test steps

[0066] 1) Measure the test environment conditions: temperature, humidity, and atmospheric pressure;

[0067] 2) Check and implement safety procedures: Before charging the test equipment, the test area must be safe and personnel must be evacuated; before personnel re-enter the test area, the capacitor bank of the impulse voltage generator must be grounded;

[0068] 3) Select the initial electrode and complete the test configuration;

[0069] 4) Calibrate impulse voltage generators and measuring instruments;

[0070] 5) Keep the model in one position and perform impact discharge on the model. Check the photos taken immediately after the discharge to ensure that the attachment point of the arc on the model can be clearly identified;

[0071] 6) Apply a set of discharge tests (usually 10 times in each orientation) to the model;

[0072] 7) Adjust the model posture and electrode position;

[0073] 8) Repeat steps 1) to 7) until all electrode positions have completed the test.

[0074] 7. Test records and data analysis

[0075] 1) Record the test environment temperature, humidity and atmospheric pressure;

[0076] 2) Record the test position, number, polarity, discharge voltage, and waveform number;

[0077] 3) Record photos and descriptions of each test arrangement;

[0078] 4) Photos and description of each discharge test;

[0079] 5) Fill in the test operators and witnesses;

[0080] 6) Records of any deviation from the test procedures;

[0081] 7) Analyze the coordinates of each lightning attachment point and count the lightning attachment positions on the model.

[0082] 8. Test result output

[0083] For the ship model attachment position number, see Fig.11 , the serial numbers and corresponding device names are shown in the following table:

[0084]

[0085] The results of the lightning attachment test on a scaled ship model simulating a natural lightning leader are as follows:

[0086]

[0087]

[0088]

[0089]

[0090] (1) Lightning strike probability at different locations

[0091] When the lightning leader electrode is located in different directions, the statistical results of the lightning attachment position and its probability are shown in the following table:

[0092]

[0093]

[0094] The conclusion is as follows:

[0095] 1) When the incident lightning leader comes from direction A, the probability of the bow flagpole, lightning rod and stern flagpole being struck by lightning is the highest, all of which are 18.2%.

[0096] 2) When the incident lightning leader comes from the B and G directions (the B and G directions are symmetrical based on the central axis of the ship), the probability of the lightning rod and the stern flagpole being struck by lightning is the highest, both 18.2%. The probability of the bow flagpole being struck by lightning is slightly lower than that of the lightning rod and the stern flagpole, at 16.4%.

[0097] 3) When the electrodes are from the C and F positions, more than half of the lightning leaders hit the sea surface.

[0098] 4) The lightning leaders in directions D and E all struck the sea surface.

[0099] (2) Probability of lightning strike on ship deck equipment

[0100] The statistical results of the probability of lightning strike location attachment in various directions and regions are shown in the following table:

[0101]

[0102] The conclusion is as follows:

[0103] 44.1% of lightning leaders are attached to the sea surface. The probability of lightning leaders attaching to the stern flagpole, lightning rod and bow flagpole of the ship is relatively large, accounting for 9%, 7.7% and 7.2% respectively.

[0104] If the sea surface lightning strike is ignored, the probability of each component on the ship being struck by lightning is analyzed separately. The statistical results of the probability of each direction and area lightning strike position being struck are shown in the following table:

[0105]

[0106] Embodiment 2: This embodiment provides a method for predicting the attachment point of ship lightning with a natural lightning leader, which mainly includes:

[0107] S1, natural lightning leader simulation. Rod electrodes are used to simulate natural lightning downward leaders. A lightning attachment test is carried out using a ship scale model with a scale of 1 / 20. According to NFPA 780 (Standard for the Installation of Lightning Protection Systems, 2020 Edition), the ship lightning protection adopts a strike distance of 30m, and the closest distance between the high-voltage rod electrode and the surface of the ship model is determined to be 1.5m.

[0108] S2, make the test piece. The test piece is a scaled-down model of the original ship's external structure. A full metal ship model is made of metal plates, and the model scale ratio is 1 / 20. A 1mm thick metal plate is used to simulate the seawater equivalent plane.

[0109] S3, model partition and test electrode arrangement. The scaled ship model is divided into 11 transverse areas along the horizontal direction, and each transverse area is divided into 7 longitudinal areas along the end face. Considering the left-right symmetry of the ship, there are 44 test areas in total. In the test, the model posture is adjusted and the electrode position is changed to simulate the direction in which the lightning leader may enter during the ship's navigation.

[0110] S4, test arrangement. Design the test wiring and arrangement scheme for simulating the natural lightning leader test. The high-voltage electrode is connected to the high-voltage end of the impulse voltage generator. The ship model is placed on a grounded metal plate simulating the seawater equivalent plane. The return line of the impulse voltage generator is connected to the grounded metal plate. The output voltage of the impulse voltage generator is sent to the oscilloscope through a coaxial cable after a voltage divider for measurement.

[0111] S5, test waveform. The voltage waveform that allows the gap between the test piece and the electrode to break down within 2μs±1μs is selected. The amplitude of the test waveform is determined by the test piece being broken down or flashover sliding over the test piece. A 50% breakdown voltage of 1.2 times the gap is applied to ensure that the gap can be broken down each time the test is performed.

[0112] S6, determine the test steps. Design the test steps and complete the simulation test of all electrode positions.

[0113] S7, test record and data analysis. Record the test data and conduct statistical analysis to obtain the location and possibility of lightning attachment or breakdown in various areas of the ship under the natural lightning leader.

[0114] Furthermore, all parts involved in this application that are not described in detail are the same as the prior art or are implemented using the prior art.

[0115] In summary:

[0116] The present invention proposes a method for predicting the lightning attachment point of a ship with a natural lightning leader. By conducting a lightning attachment test on a scaled model of a ship simulating a natural lightning leader, the area, position and number of times that the ship deck and various equipment and components on the deck are attached or penetrated by lightning can be counted, thereby accurately predicting the probability of lightning attachment to the ship deck equipment.

[0117] At the same time, dividing the lightning attachment area of ​​the natural lightning leader according to the prediction results can provide effective support for the lightning protection of equipment and components in each lightning zone of the ship. It is of great significance for the ship's lightning protection design, evaluating the lightning strike risk of key parts of the ship and the protection effect of lightning rods.

[0118] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for predicting the attachment point of ship lightning with natural lightning leaders, characterized in that: The steps include: S1, natural lightning leader simulation: rod-shaped electrodes are selected to simulate the natural lightning downward leader; S2, making test pieces: using conductive metal materials to make a scaled model of a ship, and using a metal plate of preset thickness to simulate the seawater equivalent plane; S3, model partitioning and test electrode arrangement: the ship scale model is divided into n transverse test areas along the horizontal direction, and each transverse test area is divided into m longitudinal test areas along the end surface, and then the rod-shaped electrode is arranged just above the center of each test area; S4, test arrangement: an impulse voltage generator is connected to the rod-shaped electrode to generate a lightning simulation leader, a digital storage oscilloscope is used to record the discharge polarity, voltage amplitude and waveform, and an optical camera is used to record the discharge arc path and attachment point; S5, test waveform: the amplitude of the test waveform is determined according to whether the gap between the test piece and the rod-shaped electrode is broken down or flashed over the test piece; S6, determining the test steps: completing the simulation test of all electrode positions according to the preset test steps; S7, test record and data analysis: record the test data and conduct statistical analysis to obtain the locations where lightning is attached or penetrated in various areas of the ship under the guidance of natural lightning and the corresponding probability of lightning attachment at each location.

2. The method for predicting the attachment point of ship lightning with natural lightning leaders according to claim 1 is characterized in that: The scaled-down model of the ship includes a hull, a cabin, a lightning rod, an antenna tower, and a shortwave antenna. The scaling ratio of the scaled-down model of the ship is 1 / 20, and the closest distance between the rod-shaped electrode and the surface of the scaled-down model of the ship is 1.5 m.

3. The method for predicting the attachment point of ship lightning with a natural lightning leader according to claim 1 is characterized in that In step S3, the scaled ship model is first divided into 11 horizontal test areas along the horizontal direction, specifically: area 1, area + 1, area 2, area + 2, area 3, area + 3, area 4, area + 4, area 5, area + 5, area 6; Each transverse test area is then divided into seven longitudinal test areas along the end surface, namely: area A, area B, area C, area D, area E, area F, and area G.

4. The method for predicting the ship lightning attachment point of a natural lightning leader according to claim 3 is characterized in that: The rod-shaped electrodes are arranged in different test areas to simulate the directions in which the lightning leaders of ships in different postures may enter during navigation.

5. The method for predicting the attachment point of ship lightning of a natural lightning leader according to claim 1 is characterized in that In step S4, the high voltage end of the impulse voltage generator is connected to the rod-shaped electrode, the scaled ship model is placed on a grounded metal plate simulating a seawater equivalent plane, and the ground end of the impulse voltage generator is directly connected to the grounded metal plate.

6. The method for predicting the ship lightning attachment point of a natural lightning leader according to claim 5, characterized in that: The output voltage of the impulse voltage generator is sent to an oscilloscope through a coaxial cable after passing through a voltage divider to record the discharge polarity, voltage amplitude and waveform of the rod-shaped electrode.

7. The method for predicting the attachment point of ship lightning of a natural lightning leader according to claim 1 is characterized in that In step S5, a breakdown voltage of 1.2 times of 50% of the gap is applied to ensure that the gap can be broken down in each test.

8. The method for predicting the attachment point of ship lightning of a natural lightning leader according to claim 1 is characterized in that In step S6, the test step includes: 1) Measurement test environmental conditions: The environmental conditions include temperature, humidity, and atmospheric pressure; 2) Check the test equipment and implement safety procedures: Before charging the test equipment, personnel must be evacuated, and before personnel re-enter the test area, the capacitor bank of the impulse voltage generator must be grounded; 3) Select the initial electrode and complete the experimental equipment layout; 4) Calibrate impulse voltage generators and measuring instruments; 5) Keep the scaled model of the ship in the same position and conduct shock discharge on the model. Immediately after the discharge, check the photos taken by the optical camera to ensure that the attachment point of the arc on the model can be clearly identified in the photos; 6) Apply a set of discharge tests to the model; 7) Adjust the model posture and electrode position; 8) Repeat steps 1) to 7) until all electrode positions have completed the test.

9. The method for predicting the attachment point of ship lightning of a natural lightning leader according to claim 1 is characterized in that In step S7, the test data is recorded, including: recording the electrode position, discharge times, polarity, discharge voltage, waveform number of each test, and recording the coordinates of each lightning attachment point.

10. The method for predicting the ship lightning attachment point of a natural lightning leader according to claim 9, characterized in that: By counting the lightning attachment positions on the scaled-down model of the ship in each test, the probability of each area of ​​the ship being struck by lightning under the natural lightning leader is obtained.

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