Effectiveness test method for drainage port of open cargo hold of open ship

Abstract

The invention discloses a method for testing the effectiveness of a drainage port of an open cargo hold of an open ship, and the method is characterized in that the method comprises the steps: simulating a test environment condition and a test object; determining the most unfavorable opening cargo hold of the open container ship; simulating the immersion volume of the open cargo hold of the open ship; injecting water into each open cargo hold; carrying out an open cargo compartment drainage port effectiveness test; and evaluating a test result. The method has the advantages of wide application range, high accuracy, high reliability, high repeatability and high safety.

Description

Technical Field

[0001] The present invention relates to the technical field of ships, and particularly relates to a method for testing the effectiveness of drainage scuppers of an open cargo hold of an open ship. Background Art

[0002] In recent years, the demand for open ships has increased significantly. The International Maritime Organization and classification societies have raised the requirements for ship safety and seaworthiness, stipulating that open ships need to examine the drainage capacity of the drainage scuppers of the open cargo hold. The layout of the drainage scuppers is closely related to ship stability, longitudinal strength, etc. Only by reasonably designing and accurately verifying its effectiveness can the shipbuilding cost and operation risk be reduced.

[0003] Existing technologies for verifying the effectiveness of drainage scuppers include numerical simulation technology and physical model test technology. Numerical simulation technology is the simulation of computational fluid dynamics (CFD); physical model test technology is the wave tank test. The simulation of computational fluid dynamics (CFD) is to use professional software to construct a digital model of the ship and waves, and simulate the process of the open cargo hold being overtopped by waves and the drainage scuppers draining water. The wave tank test is to make a ship model in proportion in the tank, use a wave maker to simulate different sea conditions, and observe the process of the open cargo hold being overtopped by waves and the drainage scuppers draining water through experiments.

[0004] When the ship is sailing, the water volume in the open cargo hold increases due to being overtopped by waves and rainfall, and decreases due to the drainage of the drainage scuppers. This is all dynamic and related to various factors such as the instantaneous overtopping volume, several drainage scuppers on the ship draining water simultaneously, and the movement of the ship in waves. The computational fluid dynamics (CFD) technology has limited ability to simulate complex wave phenomena and is difficult to accurately capture the dynamic changes.

[0005] For the wave tank test technology, due to the relatively late start of domestic wave tanks, it is difficult to accurately grasp issues such as how to realistically construct the structural characteristics of a full-scale ship, how to construct the structural characteristics of the drainage scuppers, how to simulate the flooded volume of the open cargo hold, and how to design the test process. It is very difficult to ensure the accuracy and reliability of the test.

[0006] The model test for the effectiveness of the drainage scuppers of the open cargo hold of an open ship is a model test that simulates the ship sailing in complex sea conditions, where sea waves, rainwater, etc. continuously accumulate in the open cargo hold, the ship's drainage system fails, and only the drainage scuppers of the cargo hold drain water. This is a dynamic process used to verify whether the drainage capacity of the drainage scuppers can ensure the safe navigation of the ship and prevent the ship from capsizing. This test is quite difficult. Once it fails, not only will the ship model suffer serious damage, but the test equipment may also be greatly damaged, resulting in high economic losses and waste of practical costs.

[0007] Currently, the relevant specifications are relatively brief and lack specific guidance, resulting in difficulties in accurately carrying out the test.

[0008] The paper "13000DWT open multi-purpose ship seakeeping test study" (author He Xinyu et al., Ship and Ocean Engineering, Vol. 33, No. 5, 2017 (Total No. 117)) discloses the study of open seakeeping model test on open multi-purpose ship. This prior art has the following deficiencies: First, the prior art proposes "filling water into the cargo hold to the lower edge of the drainage port to put the ship model in a static equilibrium state. Creatively adopting an equivalent elbow." Because the distance between the top of the equivalent elbow and the lower edge of the drainage port on the actual ship is greater than 1m, when water is poured to the lower edge of the drainage port, the water in the cargo hold does not flow out of the ship through the top of the equivalent elbow. There is a problem that the amount of water in the open cargo hold in the test is too small, which reduces the safety of the drainage port in the actual ship application; Second, the prior art proposes that "the ship model is in a zero-speed state of transverse waves, and observe whether the water entering from the waves can be effectively discharged from the drainage port of the cargo hold to ensure that the ship model does not capsize. The cargo hold of the ship adopts an asymmetric design, and this assessment must be carried out on both sides." The impact of wave angles of 90° and 270° on the roll and water inflow of the ship was not analyzed, and the more severe wave angles were selected for testing first. There may be a situation where the test conditions carried out randomly first are safer, while the test conditions carried out later are more dangerous and may even lead to the capsizing of the ship model, test failure, and invalidation of all test conditions, resulting in many test conditions and long test time, which reduces test efficiency and increases test costs.

[0009] Third, the prior art proposes that "a certain pressure is required to open the check valve, and the check valve can only be opened when the water level in the cargo hold is about 1m higher than the check valve. The equivalent elbow is creatively used. When calculating the stability and structural strength of the cargo hold due to wave inflow, it is necessary to consider increasing the water inflow of this 1m." The effect of the elbow diameter d on the test results was not considered, and there was a problem that the test results were biased towards safety due to the inaccurate simulation of the opening pressure of the drainage port.

[0010] The paper "Study on the evaluation method of deck waves for determining the freeboard of open container ships" (author Sun Anlin et al., China Shipbuilding Volume 60, Issue 3 (Total Issue 231)) discloses the study on the evaluation method of deck waves for determining the freeboard of open container ships. The prior art has the following deficiencies: This prior art proposes "the remaining five open cargo holds shall be covered with flexible waterproof materials so as to be used to contain the accumulated water caused by the inflow of waves". In the test, there are no simulated containers in the cargo holds of the open box ship, and there is a problem that the simulation of the test object is conservative, which affects the economy of the ship.

[0011] To address the above problems, no effective solution has been proposed yet. Summary of the invention

[0012] To overcome the above-mentioned defects existing in the prior art, the present invention provides a method for testing the effectiveness of the drainage scuppers of the open cargo holds of open ships.

[0013] The present invention solves the above technical problems through the following technical solutions: A method for testing the effectiveness of the drainage scuppers of the open cargo holds of open ships, which includes: Step 1, simulating the test environment conditions and the test object; Step 2, determining the most unfavorable open cargo hold of the open container ship; Step 3, simulating the flooded volume of the open cargo hold of the open ship; For an open container ship, for the most unfavorable open cargo hold determined in Step 2, the volume below the drainage scuppers of this cargo hold is V 不利 , placing container materials so that their volume accounts for 30%V 不利 ; For an open container ship, in other open cargo holds, place fully loaded containers that are higher than the open deck. The volume below the drainage scuppers of the cargo hold is V 其他 , subtract the volume of the containers from the volume of the cargo hold below the drainage scuppers to get V 其他浸 , the volume of the cargo hold that should be flooded is 70%V 其他 , and use counterweights to compensate for the flooded volume lost due to the occupation by the containers; For open-seagoing multi-purpose ships and dry cargo ships, for each open cargo hold, the volume below the drainage scuppers is V, and place cargo materials so that their volume accounts for 10%V; For a ship model whose inner bottom of the cargo hold is not set according to the actual height, calculate the lost volume of the cargo hold. For an open container ship, calculate the lost flooded volume V according to a cargo hold permeability of 70%, and for open-seagoing multi-purpose ships and dry cargo ships, calculate the lost flooded volume V according to a cargo hold permeability of 90%, and use counterweights to compensate; 损 , and use counterweights to compensate; Step 4, filling water into each open cargo hold until the water level flows out of the side of the ship after passing over the top of the elbow pipe; Step 5, conducting a test on the effectiveness of the drainage scuppers of the open cargo hold; For symmetrically arranged open ships, establish the test condition D001 for the effectiveness of the drainage scuppers and conduct the test; For asymmetrically arranged open ships, establish the test conditions D001 and D002 for the effectiveness of the drainage scuppers, analyze the influence of the wave direction angles of 90° and 270° on the rolling and overwashing of the ship, and select the more severe wave direction angle to conduct the test first; Step 6, evaluating the test results.

[0014] Further, in Step 1, elbows are installed at the inlets of the drainage scuppers of each cargo hold to simulate the process of the water level in the cargo hold pressing open the check valve of the drainage scupper and flowing outboard; the diameter of the elbow is the same as that of the drainage scupper, and the height of the elbow is h + d, where h is the minimum height of the water level in the cargo hold pressing open the valve determined according to the opening pressure of the check valve of the drainage scupper of the actual ship; d is the diameter of the drainage scupper.

[0015] Further, the elbow is formed by sleeving multiple sleeves; from the outside to the inside, the diameters of the sleeves decrease in sequence; the diameter of the pipe orifice of the sleeve is larger than the diameter below the pipe orifice of the sleeve.

[0016] Further, 1 to 2 additional drainage scuppers are added near each drainage scupper. As an additional measure, when it is necessary to adjust the diameter of the drainage scupper, they are adjusted to the open state.

[0017] Further, Step 2 includes: establishing the preliminary test condition B001, where the open-top box ship is tested at zero speed in a beam sea with a wave direction angle of 90° or 270°, and no containers are loaded in all open cargo holds; the test time of the preliminary test condition does not need to correspond to the actual ship time of 1 h; measuring the water inflow into each open cargo hold under the preliminary test condition to determine the most unfavorable open cargo hold.

[0018] Further, in Step 3, when compensating with counterweights, the center of gravity of the counterweights should correspond to the center of gravity of the lost immersion water volume of the cargo hold.

[0019] Further, during the test, the optical motion test equipment is removed from the ship model.

[0020] Further, Step 4 includes: sequentially filling water into each open cargo hold until the top of the drainage scupper elbow is submerged and the water flows out of the drainage scupper; the ship model reaches a static equilibrium state, and the immersion condition C001 is established.

[0021] Further, in Step 6, when evaluating the test results, for a ship that meets the following requirements, the setting of the drainage scuppers of the open cargo hold is effective: during the model test, the water level in any open cargo hold does not continuously increase and the ship does not capsize.

[0022] Further, for a ship that does not meet the requirements for the effectiveness of the setting of the drainage scuppers of the open cargo hold, the following measures can be taken: enlarging the size of the drainage scupper or opening the additional drainage scupper, repeating Steps 4 to 6, and explaining in the test report and making corresponding settings on the actual ship.

[0023] The beneficial effects of the present invention are as follows: The method of the present invention has a wide range of applications and can be applied to all open ships in limited navigation areas and unlimited navigation areas. The method of the present invention can simulate complex wave phenomena and accurately capture dynamic changes; this method can accurately simulate the environmental conditions required by the specifications, truly construct the structural characteristics of the actual ship, design the test process scientifically and reasonably, provide countermeasures, and ensure the accuracy and reliability of the test; the test method has high repeatability and high safety. The method of the present invention can reduce costs and improve efficiency; it avoids the over-conservative simulation of the test object and test conditions, which affects the economy of the ship. It avoids operation errors such as inaccurate simulation of the opening pressure of the drainage side port and too small water ingress in the cargo hold, and reduces the safety of actual ship applications. The method of the present invention provides reasonable countermeasures for various special situations in the test to ensure the smooth completion of the test. It avoids problems such as increasing the number of tests and delaying the design and construction cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic structural view of a bent pipe according to a preferred embodiment of the present invention.

[0025] Figure 2 is Figure 1 sectional view A-A in DETAILED DESCRIPTION OF THE INVENTION

[0026] The following gives a preferred embodiment to more clearly and completely illustrate the present invention.

[0027] The cargo hold drainage side port is an opening provided on both sides of the hull above the full load waterline in the cargo hold area, passing through the hull inside and outside, and equipped with a check valve. Under any circumstances, the water in the cargo hold can overflow outside the ship through the check valve, while the seawater outside the cargo hold cannot enter the cargo hold through the opening. The effectiveness model test of the open cargo hold drainage side port of an open ship is a test to verify whether the drainage volume of the drainage side port can ensure that the ship will not capsize.

[0028] The present invention provides a method for testing the effectiveness of the open cargo hold drainage side port of an open ship. The purpose of the present invention is to standardize the test object and working conditions of the model test, standardize the test process, accurately verify the effectiveness of the drainage side port, and ensure the safety and economy of the ship.

[0029] A method for testing the effectiveness of the open cargo hold drainage side port of an open ship, which includes: Step 1, simulating the test environmental conditions and test object; Step 2, determining the most unfavorable open cargo hold of the open hatch container ship; Step 3, simulating the immersed volume of the open cargo hold of the open ship; Step 4, injecting water into each open cargo hold; Step 5, conducting an effectiveness test on the open cargo hold drainage side port; Step 6, evaluating the test results.

[0030] Among them, Step 1 belongs to the pre - test preparation stage, Steps 2 - 5 are the test stage, and Step 6 is the test result evaluation stage. The test stage should be carried out under the test environmental conditions and on the test object in Step 1. Therefore, the content described in "the pre - test preparation stage" below is also the conditions to be met when conducting the test in the test stage.

[0031] To avoid repetition, when the following text quotes the previous text, the method of using the serial number of the quoted content plus quotation marks to replace the quoted content is adopted. For example, when the following text quotes "1.3.1" in the previous text, "1.3.1" in the following text refers to the content in "1.3.1" of "1. The pre - test preparation stage"; the specific content of "1.3.1" will not be repeated in the following text.

[0032] 1 The pre - test preparation stage 1.1 Simulation of environmental conditions 1.1.1 The test should be carried out in long - crested irregular waves. The JONSWAP spectrum (i.e., the Joint North Sea Wave Project, English name: Joint North Sea Wave Project, abbreviated as JONSWAP) can be used for the test. For ships operating only in restricted waters, other wave spectra approved by the competent authority can be used.

[0033] 1.1.2 For ships sailing in different navigation areas, the test should generate waves with a significant wave height in accordance with Table 1 under the most unfavorable wave period (crossing zero).

[0034] 1.2 Simulation of test objects 1.2.1 For the test model, in addition to requiring the shape of the underwater part to be similar to that of the actual ship, the shape of the above - water part also meets the similarity with the actual ship.

[0035] 1.2.2 The division of the ship model cargo holds should be consistent with that of the actual ship, and the length, width, and height of each cargo hold hatch should be similar to those of the actual ship. If the inner bottom height of the ship model cargo hold needs to be raised, the impact of the raised inner bottom on the reduction of the cargo hold flooded volume should be considered.

[0036] 1.2.3 Anti - rolling measures such as bilge keels and anti - rolling tanks should be fully considered and be similar to those of the actual ship.

[0037] 1.2.4 For open - top container ships, when individual cargo holds are equipped with hatch covers, in the model test, this cargo hold can be simulated as having a hatch cover, and containers are loaded on it, and seawater does not enter this cargo hold.

[0038] 1.2.5 For open-sea navigable multi-purpose dry cargo ships and ordinary dry cargo ships, for the cargo holds where the hatch covers are not opened during navigation, the cargo holds can be simulated as having hatch covers in the model test, and seawater is not pumped into these cargo holds.

[0039] 1.2.6 The height, quantity, and dimensions of the drainage scuppers of each open cargo hold meet the similarity with the actual ship.

[0040] 1.2.7 Hinged flaps are installed at the outlets of the drainage scuppers of each cargo hold to simulate the one-way opening characteristics of the drainage scuppers.

[0041] 1.2.8 Elbows are installed at the inlets of the drainage scuppers of each cargo hold to simulate the process of the water level in the cargo hold pressing open the check valve of the drainage scupper and flowing out of the ship's side. The diameter of the elbow is the same as the diameter of the drainage scupper, and the height of the elbow is h + d. Among them, h is the minimum height of the water level in the cargo hold pressing open the valve according to the opening pressure of the check valve of the drainage scupper of the actual ship; d is the diameter of the drainage scupper.

[0042] The structure of the elbow is as Figure 1 and Figure 2 shown. The elbow 10 is arranged in the cargo hold, and the elbow is connected to the drainage scupper 20. The drainage scupper 20 extends from the longitudinal bulkhead 21 of the cargo hold to the outer hull plate 22.

[0043] 1.2.9 Additional measures that can be added to quickly adjust the size of the drainage scupper during the test, such as a multi-layer sleeve structure.

[0044] The structure of the elbow is as Figure 1 and Figure 2 shown. The elbow is formed by sleeving multiple sleeves. The elbow in this embodiment is formed by sleeving three sleeves. The elbow includes the outermost sleeve 10, the middle sleeve 11, and the innermost sleeve 12. From the outside to the inside, the diameters of the sleeves decrease in sequence. The pipe orifice diameter of the sleeve is greater than the diameter below the pipe orifice of this sleeve. Among two adjacent sleeves, the pipe orifice diameter of the inner sleeve is greater than the diameter below the pipe orifice of the outer sleeve. This structure can prevent the accumulated water in the open cargo hold from directly flowing out of the ship's side through the elbow with a larger diameter on the outer layer. From the inside to the outside, the heights of the three sleeves are h1 + d1, h2 + d2, and h3 + d3 respectively.

[0045] 1.2.10 Alternatively, 1 to 2 spare drainage scuppers can be added near each drainage scupper as an additional measure. When it is necessary to adjust the diameter of the drainage scupper, they are adjusted to the open state.

[0046] 1.2.11 During the test, the optical motion test equipment is removed from the ship model to prevent damage to the equipment caused by the capsizing of the ship model. There is no need to measure parameters such as the ship's motion, speed, and acceleration.

[0047] 1.3 Ship model loading plan and debugging method 1.3.1 During the test, the draft of the ship model is adjusted to a position similar to the deepest draft T (minimum freeboard) of the actual ship in open sea navigation, with a horizontal trim.

[0048] 1.3.2 The initial metacentric height GM of the ship model is the GM value corresponding to the deepest draft in open sea navigation on the GM limit curve. The GM limit curve is obtained from the probabilistic damage stability calculation of the ship according to the International Convention for the Safety of Life at Sea.

[0049] 1.3.3 Determine the loading plan A001 of the ship model based on "1.3.1" and "1.3.2". Adjust the center of gravity, longitudinal moment of inertia and transverse moment of inertia of the ship model to be similar to those of the actual ship according to the loading plan A001.

[0050] 1.3.4 Conduct a free rolling decay test on the ship model in still water at zero speed with the loading plan A001, and measure the natural rolling period, decay coefficient, etc. of the ship.

[0051] 1.4 Test speed 1.4.1 Zero speed (the ship is in a powerless state).

[0052] 2 Test stage 2.1 Determine the most unfavorable open cargo hold of the open-top box ship 2.1.1 Establish the preliminary test condition B001 of the open-top box ship and conduct the test at zero speed in a beam sea with a wave direction angle of (90° or 270°). No containers are loaded in all open cargo holds. The test time of the preliminary test condition does not need to correspond to 1 hour of the actual ship time. The preliminary test conditions are shown in Table 2.

[0053] 2.1.2 Measure the amount of water entering each open cargo hold in the preliminary test condition and determine the most unfavorable open cargo hold. Take a ship with 3 open cargo holds as an example (assuming the hatch opening area of the first cargo hold is 400m 2 , the hatch opening area of the second cargo hold is 800m 2 , and the hatch opening area of the third cargo hold is 500m 2 ). See Table 3 for details.

[0054] As can be seen from the table, the second cargo hold is the most unfavorable open cargo hold.

[0055] 2.2 Flooding the open cargo hold 2.2.1 The ship model is free and unconstrained, protected by a hook and a soft rope (the soft rope is in a completely relaxed state) to facilitate salvage when the ship model capsizes.

[0056] 2.2.2 For the open-top box ship, verify the most unfavorable open cargo hold according to "2.1", and the volume below the drainage gunwale of this cargo hold is V 不利, place container materials, including container simulation materials (foam, wooden blocks, etc.), cable protection covers, counterweight blocks, etc., so that the volume of the container materials accounts for 30%V 不利 .

[0057] 2.2.3 For open-top container ships, other open cargo holds can be simulated as containers fully loaded and protruding above the open deck. The volume below the drainage scupper of the cargo hold is V 其他 , subtract the volume of the containers from the volume of the cargo hold below the drainage scupper to get V 其他浸 , the immersed volume of the cargo hold should be 70% V 其他 , the immersed volume lost due to the occupation of the containers (i.e., 70% V 其他 - V 其他浸 ) is compensated with counterweight blocks. Place the counterweight blocks accurately so that their center of gravity corresponds to the center of gravity of the lost immersed water volume.

[0058] 2.2.4 For multi-purpose dry cargo ships and ordinary dry cargo ships that can sail with open hatches, the volume below the drainage scupper of the open cargo hold is V. Place cargo materials, including cargo simulation materials (foam, wooden blocks, etc.), cable protection covers, counterweight blocks, etc., so that the volume of the cargo materials accounts for 10%V.

[0059] 2.2.5 For ship models that do not set the inner bottom of the cargo hold at the actual height according to "1.2.2", the impact of the raised inner bottom on the reduction of the immersed volume of the cargo hold should be considered. Calculate the lost volume of the cargo hold. For open-top container ships, calculate the lost immersed volume according to a cargo hold permeability of 70%, and for multi-purpose dry cargo ships and ordinary dry cargo ships that can sail with open hatches, calculate the lost immersed volume according to a cargo hold permeability of 90%. Compensate with counterweight blocks and place the counterweight blocks accurately so that their center of gravity corresponds to the center of gravity of the lost immersed water volume of the cargo hold.

[0060] 2.2.6 Open all the drainage scuppers of the cargo hold (except for the spare drainage scuppers in "1.2.10"), and inject water into each open cargo hold in turn until the water flows out of the drainage scupper through the top of the elbow, then stop injecting water.

[0061] 2.2.7 The ship model reaches a static equilibrium state, and the immersed condition C001 is established.

[0062] 2.3 Effectiveness test of the drainage scuppers of the open cargo hold 2.3.1 For symmetrically arranged open ships, establish the effectiveness test condition D001 of the drainage scuppers. The ship model is tested at zero speed in a beam sea under the immersed condition C001, and the test time should correspond to at least 1h of the actual ship time.

[0063] 2.3.2 For open ships with asymmetric arrangements, such as ships with only one side equipped with a derrick crane, chimney and other structures that affect seawater from entering the cargo hold, or ships with open cargo holds not centered symmetrically, establish the effectiveness test conditions D001 and D002 for the drainage scuppers. Conduct tests at zero speed in beam seas with wave angles of 90° and 270°. The test time should correspond to at least 1 hour of actual ship time.

[0064] The effectiveness test conditions for the drainage scuppers of open cargo holds are shown in Table 4.

[0065] 2.3.3 For open ships with asymmetric arrangements, according to the floating state of the ship model in flooding condition C001, analyze the influence of wave angles of 90° and 270° on the rolling and overtopping of the ship, and select the more severe wave angle to conduct the test first.

[0066] 3 Evaluation of Test Results 3.1 Evaluation of the effectiveness of the drainage scuppers of open cargo holds on open ships 3.1.1 For ships that meet the following requirements, the setting of the drainage scuppers of open cargo holds is effective: In the model test, the water level in any open cargo hold does not continuously increase and the ship does not capsize.

[0067] 3.1.2 For ships that do not meet the requirements in "3.1.1", the following measures can be taken: Enlarge the size of the drainage scuppers, or open the standby drainage scuppers, repeat the effectiveness test of the drainage scuppers of open cargo holds, and explain it in the test report and make corresponding settings on the actual ship.

[0068] The present invention can standardize the model test objects and conditions, standardize the test process, accurately verify the effectiveness of the drainage scuppers, and ensure the safety and economy of the ship.

[0069] The present invention innovatively constructs a model test method for the effectiveness of the drainage scuppers of open cargo holds on open ships, fills the gaps in the details and depth of existing specifications, provides a more comprehensive implementation basis and guiding criteria, and provides an indispensable key reference for ship design and navigation safety.

[0070] The beneficial effects of the present invention are as follows: The key factors affecting the test results of the effectiveness of the drainage scuppers are: the simulation method of the cargo in the open cargo hold, the simulation method of the immersed volume of the cargo in the open cargo hold, the determination method of the immersed water level height in the open cargo hold, the simulation method of the drainage scuppers, and the sequence selection method of the effectiveness test conditions.

[0071] The paper "Study on Deck Wave Assessment Method for Determining Freeboard of Open Container Ships" (author Sun Anlin et al., China Shipbuilding Vol. 60, No. 3 (Total No. 231)) proposed that "the remaining five open cargo holds are covered with flexible waterproof materials to collect water caused by the inflow of waves", while the present invention adopts "the most unfavorable open cargo hold in transverse waves is obtained through preliminary tests, and container materials are placed in the most unfavorable open cargo hold so that its volume accounts for 30% of V 不利 The method for arranging containers in open cargo holds fully considers the loading requirements of the actual operation of the ship, overcomes the problem of conservative simulation of the test object in the prior art, and improves the economy of the ship.

[0072] The present invention innovatively proposes a method for simulating the flooding volume of an open cargo hold of an open box ship, a method for simulating the flooding volume of an open cargo hold of a navigable multipurpose ship and a dry cargo ship, and a method for simulating the flooding volume of an open cargo hold due to the inward bottom of the cargo hold not being set according to the actual height; it provides guidance for the effectiveness test of the drainage port of all open ships in all navigation areas, overcomes the problem of invalid experimental results due to the error in simulating the flooding volume of the open cargo hold, and ensures the safety of the actual ship application of the drainage port; The paper "13000DWT open multipurpose ship seakeeping test study" (author He Xinyu et al., Ship and Ocean Engineering, Vol. 33, No. 5, 2017 (No. 117 in total)) proposed "filling water into the cargo hold to the lower edge of the drainage port to put the ship model in a static equilibrium state. Creatively adopt equivalent elbows." The present invention adopts the technical feature of "filling water into each open cargo hold in turn until the water level exceeds the top of the elbow and flows out of the ship, and then stopping water filling." It fully considers the situation that the distance between the top of the elbow of the actual ship and the lower edge of the drainage port is greater than 1m, overcomes the problem of safe experimental results caused by the small volume of open cargo hold flooding in the prior art, and ensures the accuracy of the test; The above paper proposes that "a certain pressure is required to open the check valve, and the check valve can only be opened when the water level in the cargo hold is about 1m higher than the check valve. The equivalent elbow is creatively used. When calculating the stability and structural strength of the cargo hold due to wave inflow, it is necessary to consider increasing the water inflow of 1m." The present invention adopts "the elbow height is h+d, h is the minimum height of the valve opened by the water level in the cargo hold; d is the diameter of the drainage port." The influence of the elbow diameter d on the test results is taken into account, which overcomes the problem in the prior art that the test results are biased towards safety due to inaccurate simulation of the opening pressure of the drainage port, thereby ensuring the accuracy of the test.

[0073] In addition, the present invention adopts the technical features of "multi-layer casing structure, spare drainage port and other additional measures for quickly adjusting the size of the drainage port", which greatly shortens the time for test personnel to adjust the size of the drainage port and improves test efficiency.

[0074] In the above-mentioned paper, it is proposed that "when the ship model is in the zero-speed state in a beam sea, observe whether the water ingress from the wave can be effectively discharged from the drainage scuppers of the cargo hold to ensure that the ship model does not capsize. The cargo hold of this ship adopts an asymmetric design, and this assessment needs to be carried out on both the port and starboard sides." The present invention adopts the technical feature of "analyzing the influence of wave direction angles of 90° and 270° on the rolling and water ingress of the ship, and selecting the more severe wave direction angle to conduct the test first", which overcomes the situation in the prior art that the test conditions randomly carried out first may be safer, while the test conditions carried out later may be more dangerous and even lead to the capsizing of the ship model, the failure of the test, and the invalidation of all test conditions, improving the test efficiency and reducing the test cost.

[0075] The present invention has the following advantages: (1) The method of the present invention has a wide range of applications and can be applied to all open ships in limited and unlimited navigation areas; (2) The method of the present invention can simulate complex wave phenomena and can accurately capture dynamic changes; (3) The method of the present invention accurately simulates the environmental conditions required by the specifications, truly constructs the structural characteristics of the actual ship, designs the test process scientifically and reasonably, provides countermeasures, and ensures the accuracy and reliability of the test.

[0076] (4) The test method has high repeatability and high safety.

[0077] (5) The test method can reduce costs and improve efficiency; avoid being too conservative in simulating the test objects and test conditions, which may affect the economy of the ship. Avoid operation errors such as not simulating the opening pressure of the drainage scuppers and the small amount of water immersion in the cargo hold, which may reduce the safety of actual ship applications.

[0078] (6) Provide reasonable countermeasures for various special situations in the test to ensure the smooth completion of the test. Avoid problems such as increasing the number of tests and delaying the design and construction cycle.

[0079] Although the specific implementation manners of the present invention have been described above, those skilled in the art should understand that this is only an example, and the protection scope of the present invention is defined by the appended claims. Without departing from the principles and essence of the present invention, those skilled in the art can make various changes or modifications to these implementation manners, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A test method for the effectiveness of the drainage side opening of an open cargo hold of an open ship, characterized in that, It includes: Step 1, simulating the test environment conditions and test objects; Step 2, determining the most unfavorable open cargo hold of an open hatch ship; Step 3, simulating the flooded volume of the open cargo hold of an open ship; For an open-top box ship, for the most unfavorable open cargo hold determined in step 2, the volume below the drainage scupper of this cargo hold is V 不利 , place container materials so that their volume accounts for 30% of V 不利 ; For an open-top box ship, other open cargo holds are used to place containers that are fully loaded and higher than the open deck. The volume below the freeboard opening of the cargo hold is V 其他 , the volume of the cargo hold below the freeboard opening minus the volume of the containers is V 其他浸 , the volume of the cargo hold that should be flooded is 70%V 其他 , the flooded volume lost due to the occupation of containers is compensated with counterweights; For multi-purpose ships and dry cargo ships that can sail with open hatches, the volume below the drainage scupper of each open cargo hold is V, and cargo materials are placed so that their volume accounts for 10%V; For a ship model with the inner bottom of the cargo hold not set according to the actual height, calculate the lost volume of the cargo hold. For an open-top box ship, calculate the lost flooded volume V with a cargo hold permeability of 70%. For a multi-purpose ship and a dry cargo ship that can sail with an open hatch, calculate the lost flooded volume V with a cargo hold permeability of 90%. 损 , and compensate with counterweights; Step 4, injecting water into each open cargo hold until the water level flows out of the ship's side over the top of the elbow pipe; Step 5, conducting a test on the effectiveness of the drainage scuppers of the open cargo hold; For an open ship with symmetric layout, establish the test condition D001 for the effectiveness of the drainage scuppers and conduct the test; For an open ship with asymmetric layout, establish the test conditions D001 and D002 for the effectiveness of the drainage scuppers, analyze the influence of wave direction angles of 90° and 270° on the ship's rolling and overwashing and flooding, and select the more severe wave direction angle to conduct the test first; Step 6, evaluating the test results.

2. The method for testing the effectiveness of the drainage side opening of the open cargo hold of an open ship as described in claim 1, characterized in that, In Step 1, an elbow pipe is installed at the inlet of the drainage scupper of each cargo hold to simulate the process of the water level in the cargo hold pressing open the check valve of the drainage scupper and flowing out of the ship's side; the diameter of the elbow pipe is the same as that of the drainage scupper, and the height of the elbow pipe is h + d, where h is the minimum height of the water level in the cargo hold pressing open the valve determined according to the opening pressure of the check valve of the actual ship's drainage scupper; d is the diameter of the drainage scupper.

3. The method for testing the effectiveness of the drainage side opening of the open cargo hold of an open ship as described in claim 2, wherein The elbow pipe is composed of multiple sleeves sleeved together; from the outside to the inside, the diameters of the sleeves decrease in sequence; the diameter of the pipe orifice of the sleeve is larger than the diameter below the pipe orifice of the sleeve.

4. The method for testing the effectiveness of the drainage scuppers of the open cargo hold of an open ship according to claim 2, wherein One or two spare drainage scuppers are added near each drainage scupper as an additional measure. When it is necessary to adjust the diameter of the drainage scupper, they are adjusted to the open state.

5. The test method for the effectiveness of the drainage scupper of the open cargo hold of an open ship as described in claim 1, characterized in that Step 2 includes: establishing the preliminary test condition B001, conducting a test on the open hatch ship at zero speed in a beam sea with a wave direction angle of 90° or 270°, and no containers are loaded in all open cargo holds; the test time of the preliminary test condition does not need to correspond to the actual ship time of 1 h; measuring the water inflow into each open cargo hold in the preliminary test condition and determining the most unfavorable open cargo hold.

6. The test method for the effectiveness of the drainage scuppers of the open cargo hold of an open ship as claimed in claim 1, wherein, In Step 3, when compensating with counterweights, the center of gravity of the counterweights should correspond to the center of gravity of the flooded volume lost in the cargo hold.

7. The method for testing the effectiveness of the drainage scupper of the open cargo hold of an open ship as described in claim 1, characterized in that, During the test, the optical motion test equipment is removed from the ship model.

8. The method for testing the effectiveness of the drainage scuppers of the open cargo hold of an open ship as claimed in claim 1, wherein Step 4 includes: injecting water into each open cargo hold in sequence until the water level exceeds the top of the drainage scupper elbow pipe and the water flows out of the drainage scupper; the ship model reaches a static equilibrium state, and the flooded condition C001 is established.

9. The method for testing the effectiveness of the drain scuppers of the open cargo hold of an open ship according to claim 1, wherein, In Step 6, when evaluating the test results, for a ship that meets the following requirements, the setting of the drainage scuppers of the open cargo hold is effective: in the model test, the water level in any open cargo hold does not continuously increase and the ship does not capsize.

10. The method for testing the effectiveness of the drainage side opening of an open cargo hold of an open ship as claimed in claim 9, characterized in that, For a ship that does not meet the requirement that the setting of the drainage scuppers of the open cargo hold is effective, the following measures can be taken: expanding the size of the drainage scupper or opening the spare drainage scupper, repeating Steps 4 to 6, and explaining in the test report and making corresponding settings on the actual ship.

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