A method and system for separating abnormal noise sources at the stern of a ship

Abstract

The present invention provides a method and system for separating abnormal noise sources at the stern of a ship, comprising: utilizing a ship noise reference database, combining the navigation characteristics of the ship in the water, and sequentially collecting noise source correlation characteristics when the ship is in the individual start-up and stop states of each main and auxiliary equipment, steady-state operating conditions, and unsteady-state operating conditions; applying a preset combination analysis of the noise source correlation characteristics including total level comparison analysis, 1 / 3 octave band analysis, line spectrum analysis, DEMON spectrum analysis, frequency multiplication analysis, and LOFAR spectrum analysis to obtain multiple abnormal noise source correlation results at the stern of the ship; determining the comprehensive noise proportion of the multiple abnormal noise source correlation results at the stern of the ship, and generating abnormal noise source separation analysis results at the stern of the ship. The present invention can solve the problems of incomplete testing, inaccurate positioning, and unclear abnormal cause analysis during the abnormal noise processing process at the stern of the ship, and provide technical support for formulating abnormal noise investigation and repair plans.

Description

Technical Field

[0001] The present invention relates to the technical field of noise measurement, and in particular to a method and system for separating abnormal noise sources at the stern of a ship. Background Art

[0002] Due to the numerous and complex devices at the stern of a ship, addressing abnormal stern noise involves numerous projects and a long construction period. Furthermore, the numerous noise sources, extensive transmission paths, complex causes, and the coupling of multiple factors make it difficult to isolate, locate, and analyze the causes of abnormal noise, further hindering the troubleshooting and remediation of abnormal noise. According to incomplete statistics, the time it takes to resolve abnormal stern noise issues ranges from one to three months to six to twelve months, with some cases even remaining unresolved for years.

[0003] In recent years, in order to solve the problem of ship stern noise, a lot of testing and analysis have been carried out in related research fields, but the results have not been good. There are still problems such as incomplete testing, inaccurate positioning, and unclear analysis of the causes of abnormalities. Summary of the Invention

[0004] The present invention provides a method and system for separating abnormal noise sources at the stern of a ship, which are used to solve the problems of frequent abnormal noise phenomena at the stern of a ship in the prior art, such as incomplete testing, inaccurate positioning, and unclear analysis of the causes of abnormal noise. The method solves the problems of difficulty in separating the noise sources at the stern of a ship and difficulty in locating the causes of abnormal noise.

[0005] In a first aspect, the present invention provides a method for separating abnormal noise sources at the stern of a ship, comprising:

[0006] Obtaining multi-dimensional noise test results of a ship, and constructing a ship noise reference database based on the acoustic characteristics of the ship when there is no abnormal noise corresponding to the multi-dimensional noise test results of the ship;

[0007] Using the ship noise reference database and combining the ship's navigation characteristics in water, noise source correlation characteristics are collected in sequence when the ship is in the start-up and stop states of each main and auxiliary equipment, steady-state operating conditions, and unsteady-state operating conditions;

[0008] The noise source correlation characteristics are analyzed using a preset combination of total level comparison analysis, 1 / 3 octave band analysis, line spectrum analysis, DEMON spectrum analysis, octave analysis, and LOFAR spectrum analysis to obtain the correlation results of multiple abnormal noise sources at the stern of the ship;

[0009] Determine the comprehensive noise proportion of the correlation results of the multiple abnormal noise sources at the rear of the ship, and generate a separation analysis result of the abnormal noise sources at the rear of the ship.

[0010] According to a method for separating abnormal noise sources at the stern of a ship provided by the present invention, before constructing a ship noise reference database, the method further includes: obtaining a ship multi-dimensional noise test result; and according to the acoustic characteristics of the ship when there is no abnormal noise corresponding to the multi-dimensional noise test result of the ship, the method further includes:

[0011] Obtain the time sensitivity and condition dependence of abnormal ship noise, and collect users' overall judgment information on noise;

[0012] According to different ship types, stern structures and design features, determine the noise sources and related influencing factors at the stern of the ship, and obtain the ship design parameters and usage records;

[0013] Based on the structural vibration theory, shafting torsional vibration theory and propeller noise generation excitation principle, the characteristic differences and correlations of various noise sources are determined.

[0014] According to a method for separating abnormal noise sources at the stern of a ship provided by the present invention, obtaining multi-dimensional noise test results of the ship includes:

[0015] Determine the ship's operating condition design, measurement point layout, and measurement parameters based on the type of noise source at the ship's stern. The operating condition design includes separate start and stop of each main and auxiliary engine, a constant speed straight-through test condition, and a variable speed condition. The measurement point layout includes measurement point location and measurement point type. The measurement parameters include vibration acceleration and underwater sound pressure.

[0016] When each main and auxiliary equipment is started and stopped separately, the correlation between each abnormal noise source and each main and auxiliary equipment is determined by turning on and off each main and auxiliary equipment one by one;

[0017] Under the uniform speed straight-line test condition, the shafting speed increase and decrease tests are performed on the X, Y, and Z axis speeds of the shafting speed in the X axis speed range, the Y axis speed range, and the Z axis speed range, respectively, to obtain the shafting speed at which the abnormal noise occurs at the lowest speed, the shafting speed at which the abnormal noise occurs at the highest speed, and the shafting speed at which the abnormal noise occurs frequently;

[0018] Under the variable speed conditions, a shafting parking and taxiing test and a propeller acceleration test are respectively performed;

[0019] The measuring point positions include a shafting support part, an area near the propeller, a hull structure and an outboard appendage structure. The shafting support part is tested for three-way vibration to obtain shafting vibration acceleration, the area near the propeller is tested for three-way vibration to obtain propeller vibration acceleration, the area near the propeller is tested for unidirectional water sound to obtain propeller water sound pressure level, the hull structure is tested for single-item vibration to obtain hull vibration acceleration, the outboard appendage structure is tested for unidirectional water sound to obtain outboard appendage water sound pressure level, and the outboard appendage structure is tested for unidirectional vibration to obtain outboard appendage vibration acceleration.

[0020] According to a method for separating abnormal noise sources at the stern of a ship provided by the present invention, a ship noise reference database is constructed based on the acoustic characteristics of the ship when there is no abnormal noise corresponding to the multi-dimensional noise test results of the ship, including:

[0021] Collecting the multi-dimensional noise test results of the ship corresponding to different classification test results of the ship delivery test period, the ship use period, the normal test state of the same type of ship and the abnormal test state of the same type of ship;

[0022] The ship noise reference database is composed of test results of different categories.

[0023] According to a method for separating abnormal noise sources at the stern of a ship provided by the present invention, the method utilizes the ship noise reference database and combines the navigation characteristics of the ship in the water body to collect noise source correlation characteristics in sequence when the ship is in the start-up and stop states of each main and auxiliary equipment, steady-state operating conditions, and unsteady-state operating conditions, including:

[0024] When each main and auxiliary equipment is started and stopped separately, if any abnormal noise appears when the equipment is turned on and disappears when it is turned off, and has obvious noise characteristics at the preset points of the equipment, then any abnormal noise is determined to be the noise associated with the main and auxiliary equipment;

[0025] Under steady-state conditions, comparisons are made between different measuring points under the same operating condition and between the same measuring points under different operating conditions to determine the main characteristics, associated locations, and changing patterns of abnormal noise.

[0026] Under unsteady-state conditions, the correlation between abnormal noise and propeller, shafting and outboard structure is determined.

[0027] According to a method for separating abnormal noise sources at the stern of a ship provided by the present invention, a preset combination of overall level comparison analysis, 1 / 3 octave band analysis, line spectrum analysis, DEMON spectrum analysis, octave analysis, and LOFAR spectrum analysis is used to analyze the noise source correlation characteristics, and the abnormal noise source separation analysis results of the ship stern are obtained, including:

[0028] Perform overall level comparison analysis on different measurement points under the same working condition and the same measurement point under different working conditions under steady-state conditions, and determine overall level abnormal data based on the preset sound pressure level decibel threshold;

[0029] Performing 1 / 3 oct frequency band analysis on the total level abnormal data to determine the abnormal frequency band;

[0030] Perform line spectrum analysis on the abnormal frequency band to obtain the main characteristics of the abnormal noise, the abnormal location and related locations, and the law of abnormal noise changes with speed;

[0031] Based on frequency multiplication analysis and LOFAR spectrum analysis, the main characteristics of abnormal noise, abnormal locations and related locations, and the law of abnormal noise change with ship speed are analyzed. Combined with LOFAR spectrum analysis of the shafting parking and coasting under the unsteady working condition, the correlation results with the propeller shaft system noise are obtained;

[0032] Comparing the abnormal frequency band with the inherent structural characteristics of the abnormal part to obtain a noise correlation result with the inherent structural characteristics;

[0033] Comparing the abnormal frequency band with the inherent characteristics of the propeller to obtain a correlation result with the inherent characteristic noise of the propeller;

[0034] LOFAR spectrum analysis is performed on the propeller acceleration test under the unsteady state condition to obtain results associated with propeller noise.

[0035] According to a method for separating abnormal noise sources at the stern of a ship provided by the present invention, the method determines the comprehensive noise proportion of the correlation results of the multiple abnormal noise sources at the stern of the ship, and generates an analysis result of the separation of abnormal noise sources at the stern of the ship, including:

[0036] Respectively obtaining the result of correlation with the propeller shaft system noise, the result of correlation with the inherent structural characteristic noise, the result of correlation with the inherent propeller characteristic noise, and the deflection ratio of the result of correlation with the propeller noise, and calculating the comprehensive noise proportion;

[0037] Based on the comprehensive noise proportion, the abnormal noise source separation analysis result of the ship stern is output.

[0038] In a second aspect, the present invention further provides a system for separating abnormal noise sources at the stern of a ship, comprising:

[0039] An acquisition and construction module is used to obtain a ship multi-dimensional noise test result, and construct a ship noise reference database based on the acoustic characteristics of the ship when there is no abnormal noise corresponding to the multi-dimensional noise test result of the ship;

[0040] An acquisition module is used to use the ship noise reference database and, in combination with the ship's navigation characteristics in water, collect noise source correlation characteristics in sequence when the ship is in the start-up and stop states of each main and auxiliary equipment, steady-state operating conditions, and unsteady-state operating conditions;

[0041] An analysis module is used to analyze the noise source correlation characteristics using a preset combination of overall level comparison analysis, 1 / 3 octave band analysis, line spectrum analysis, DEMON spectrum analysis, octave analysis, and LOFAR spectrum analysis to obtain correlation results of multiple abnormal noise sources at the stern of the ship;

[0042] The separation module is used to integrate the noise analysis results of the uniform speed straight sailing condition and the noise analysis results of the variable speed condition to generate a separation analysis result of the abnormal noise source at the stern of the ship.

[0043] In a third aspect, the present invention further provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method for separating abnormal noise sources at the stern of a ship as described above is implemented.

[0044] In a fourth aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-described methods for separating abnormal noise sources at the stern of a ship.

[0045] The method and system for separating abnormal noise sources at the stern of a ship provided by the present invention, based on the existing ship structure vibration theory, combined with the characteristics of the ship in the water environment and the characteristics and generation mechanism of the ship's stern noise source, propose a testing means for effectively separating the abnormal noise sources at the stern of a ship. In addition, in view of the difficulties in separating abnormal noise, a separation method for effectively separating abnormal noise sources at the stern of a ship is proposed, which can comprehensively, quickly and effectively provide comprehensive technical support for the investigation and repair of various abnormal noises at the stern of a ship. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0047] Figure 1 1 is a flow chart of a method for separating abnormal noise sources at the stern of a ship provided by the present invention;

[0048] Figure 2 This is a flow chart of the test method for abnormal noise at the stern of a ship provided by the present invention;

[0049] Figure 3 This is a flow chart of the principle of separating abnormal noise at the stern of a ship provided by the present invention;

[0050] Figure 4 This is a schematic structural diagram of the abnormal noise source separation system for a ship stern provided by the present invention;

[0051] Figure 5 It is a structural schematic diagram of the electronic device provided by the present invention. DETAILED DESCRIPTION

[0052] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0053] In view of the common problems of incomplete testing, inaccurate positioning and unclear analysis of abnormal causes in the current technical means of processing ship stern noise, the present invention proposes a method that can effectively separate the source of abnormal noise at the stern of a ship. It can effectively solve the problems of incomplete testing, inaccurate positioning and unclear analysis of abnormal causes in the process of processing abnormal noise at the stern of a ship, and provide comprehensive technical support for the formulation of abnormal noise investigation and repair plans.

[0054] Figure 1 FIG. 1 is a flow chart of a method for separating abnormal noise sources at the stern of a ship provided by an embodiment of the present invention. Figure 1 Shown, including:

[0055] Step 100: Obtaining a ship multi-dimensional noise test result, and constructing a ship noise reference database based on the acoustic characteristics of the ship when there is no abnormal noise corresponding to the multi-dimensional noise test result of the ship;

[0056] Step 200: Using the ship noise reference database and combining the ship's navigation characteristics, noise source correlation characteristics are collected in sequence when the ship is in the start-up and stop states of each main and auxiliary equipment, steady-state operating conditions, and unsteady-state operating conditions;

[0057] Step 300: The noise source correlation characteristics are analyzed using a preset combination of overall level comparison analysis, 1 / 3 octave band analysis, line spectrum analysis, DEMON spectrum analysis, octave analysis, and LOFAR spectrum analysis to obtain correlation results of multiple abnormal noise sources at the stern of the ship;

[0058] Step 400: Determine the comprehensive noise proportion of the correlation results of the multiple abnormal noise sources at the rear of the ship, and generate a separation analysis result of the abnormal noise sources at the rear of the ship.

[0059] In one embodiment, before step 100, the method further includes:

[0060] Obtain the time sensitivity and condition dependence of abnormal ship noise, and collect users' overall judgment information on noise;

[0061] According to different ship types, stern structures and design features, determine the noise sources and related influencing factors at the stern of the ship, and obtain the ship design parameters and usage records;

[0062] Based on the structural vibration theory, shafting torsional vibration theory and propeller noise generation excitation principle, the characteristic differences and correlations of various noise sources are determined.

[0063] It should be noted that there are many noise sources at the stern of a ship and the transmission paths are complex. In addition to the direct radiation generated by the abnormal noise source itself, there is also the phenomenon of a single noise source exciting multiple structures to generate abnormal noise and multiple noise sources simultaneously exciting a single structure to generate abnormal vibration noise.

[0064] The ship benchmark database is very broad and includes almost all information. However, for abnormal tail noise, this benchmark database should be selective and targeted. Therefore, before building the database, the following should be included:

[0065] (1) The timing, conditions, phenomena and characteristics of abnormal noise should be fully investigated, researched and analyzed, especially the user's feelings and judgments on abnormal noise at the stern of the ship should be carefully listened to and analyzed.

[0066] (2) Determine the possible noise sources and related influencing factors at the stern according to the different ship types, stern structures and design features. If necessary, consult the relevant design parameters and operation records of the ship;

[0067] (3) Based on the structural vibration theory, shafting torsional vibration theory and propeller noise excitation, the differences in characteristics of each noise source and their correlation are determined.

[0068] Specifically, the main sources of noise at the stern of a ship are propeller shaft system noise, main and auxiliary engine vibration noise, and structural vibration noise. Due to different generation mechanisms, the main characteristics of abnormal noise vary. Main and auxiliary engine vibration is closely related to the equipment's operating status and is generally easy to separate. However, structural vibration noise and propeller shaft system noise are closely related to the ship's navigation status and are difficult to detect and identify by human ears inside the cabin, making separation and localization difficult.

[0069] The generation mechanism of ship stern structure vibration noise and propeller shaft system noise is as follows:

[0070] (1) Structural vibration noise

[0071] According to the structural vibration modal theory, the structural vibration response can be expressed as:

[0072] (1)

[0073] in, is the angular frequency, For structural The structural response at For structural The excitation force at the point, for Point to The frequency response function of the point has the following relationship:

[0074] (2)

[0075] in, 、 For the The modal coefficients of the first order, 、 、 Respectively modal stiffness, modal mass and modal damping, is the imaginary unit, is the modal order.

[0076] For ship structures, which are mainly composed of metal plates, modal damping is usually used. represents the damping coefficient, we can get:

[0077] (3)

[0078] in, .

[0079] From (2) and (3), we can see that the structural frequency response function It is related to modal stiffness, modal mass and damping. For a certain hull structure, the frequency response function does not change with the change of external excitation. From (1), it can be seen that under the condition of a certain frequency response function, the response of the structural system is mainly determined by the system excitation force. When the excitation force changes, the structural response will change accordingly.

[0080] In addition, during navigation, the ship's structure will be excited by fluid, mechanical equipment, and propeller shaft systems. Among them, the excitation force of mechanical equipment is closely related to the equipment's activation power and generally exhibits steady-state characteristics; the fluid-excited hull structure is closely related to the fluid excitation force. According to the relationship between the Strouhal number and frequency in fluid mechanics:

[0081] (4)

[0082] in, is the vortex shedding frequency on the structure, is the characteristic length, is the fluid velocity, is the Strouhal number. When the ship's speed changes, the fluid excitation frequency changes accordingly. The vibration response of the hull structure excited by the propeller-shaft system exhibits a clear correspondence with the shafting excitation force. That is, as the excitation force increases with speed, the structural vibration response increases; and when the shafting excitation force disappears, the vibration response characteristic disappears.

[0083] (2) Propeller shaft system noise

[0084] According to the shaft torsional vibration theory, the shaft lateral (y-direction) vibration solution is:

[0085] (5)

[0086] in, , , Wave speed The component in the transverse direction (y direction) of the axis system, represents stiffness, is the angular frequency The component in the transverse direction (y direction) of the axis system, 、 、 and Respectively The multi-order coefficients of the decomposition, represents the x-axis component, represents the time component, is the moment of inertia of the shaft interface with respect to the Z axis, m is the mass per unit length of the shaft, is the time function to be solved in the horizontal direction (y direction) of the axis system.

[0087] The vertical (Z-direction) vibration solution of the shaft system is:

[0088] (6)

[0089] in, , , Wave speed The component in the transverse direction (z direction) of the axis system, is the angular frequency The component in the transverse direction (z direction) of the axis system, 、 、 and Respectively The multi-order coefficients of the decomposition, represents the x-axis component, represents the time component, is the moment of inertia of the rotating shaft interface with respect to the Y axis, m is the mass per unit length of the shaft, It is the time function to be solved in the transverse direction (z direction) of the axis system.

[0090] The solution of the shaft-rotor torsional vibration is:

[0091] (7)

[0092] in, 、 、 、 is a parameter determined by the axis boundary conditions, Indicates angular frequency In the time dimension, Indicates wave speed Component in the time dimension.

[0093] From the above equations (5), (6), and (7), it can be seen that the shaft vibration is a broadband continuous spectrum. Under certain conditions, it will show harmonic characteristics.

[0094] According to the propeller noise generation mechanism, the average sound power spectrum of propeller noise can be expressed as:

[0095] (8)

[0096] (9)

[0097] (10)

[0098] in, is the time period, is the angular frequency, is the imaginary unit, is the pulse signal function generated by cavitation collapse, satisfying the conditions: , and when hour, ; is the cavitation noise amplitude factor generated by the propeller, is the effective pulse width, is the Fourier transformed cavitation pulse function, is a random quantity with mean 0, is the average sound power spectrum of propeller noise, is the system linear spectrum response function, is the nonlinear spectral response function of the system, is the mathematical expectation function, is a natural constant.

[0099] From formula (6), we can see that the average power spectrum of propeller cavitation noise consists of two parts: continuous spectrum and line spectrum, which are:

[0100] (11)

[0101] Line spectrum frequencies only appear At, it appears as a harmonic of the shaft frequency, For the time period.

[0102] When a propeller operates in a relatively uniform wake, a relatively stable cavitation morphology is formed. During one rotation, there is also a certain degree of axial non-uniformity, but the characteristics are generally not obvious and will not produce cavitation, "singing" or "weak singing". During use, if the propeller develops cracks, cracks, blade contamination, or poor repair, resulting in changes in the propeller state, the axial non-uniformity of the wake velocity will be exacerbated, increasing the propeller excitation force. When the excitation force frequency couples with the natural frequency of the blade structure and resonates, "singing" or "weak singing" will occur.

[0103] In summary, we can draw the following conclusions:

[0104] (1) The equipment in the cabin excites the hull structure. The structural response characteristics are determined by the stiffness and damping of the hull structure itself. The response amplitude shows a clear correspondence with the equipment excitation force.

[0105] (2) When the excitation force generated by the propeller shaft system excites the hull structure, the structural response characteristics are determined by the stiffness and damping of the hull structure itself. The amplitude of the structural response changes with the rotational speed. When the excitation force of the shaft system disappears, the vibration response disappears.

[0106] (3) When the outboard flow excites the hull structure or cavity, the structural response characteristics are determined by the stiffness and damping of the hull structure itself. The structural response amplitude has a clear corresponding relationship with the ship speed. When the speed decreases, the response amplitude characteristics decrease or disappear.

[0107] (4) The shaft system vibration is generally a continuous spectrum with harmonic characteristics, while the propeller cavitation noise is characterized by a continuous spectrum + discrete spectrum. The discrete spectrum is manifested as harmonics of the propeller blade frequency and appears at integer multiples of the shaft frequency. The propeller "singing" or "weak singing" frequency is strongly correlated with the inherent characteristics of the propeller blades. When the speed changes, the corresponding frequency will also change.

[0108] In one embodiment, step 100 includes:

[0109] Determine the ship's operating condition design, measurement point layout, and measurement parameters based on the type of noise source at the ship's stern. The operating condition design includes separate start and stop of each main and auxiliary engine, a constant speed straight-through test condition, and a variable speed condition. The measurement point layout includes measurement point location and measurement point type. The measurement parameters include vibration acceleration and underwater sound pressure.

[0110] When each main and auxiliary equipment is started and stopped separately, the correlation between each abnormal noise source and each main and auxiliary equipment is determined by turning on and off each main and auxiliary equipment one by one;

[0111] Under the uniform speed straight-line test condition, the shafting speed increase and decrease tests are performed on the X, Y, and Z axis speeds of the shafting speed in the X axis speed range, the Y axis speed range, and the Z axis speed range, respectively, to obtain the shafting speed at which the abnormal noise occurs at the lowest speed, the shafting speed at which the abnormal noise occurs at the highest speed, and the shafting speed at which the abnormal noise occurs frequently;

[0112] Under the variable speed conditions, a shafting parking and taxiing test and a propeller acceleration test are respectively performed;

[0113] The measuring point positions include a shafting support part, an area near the propeller, a hull structure and an outboard appendage structure. The shafting support part is tested for three-way vibration to obtain shafting vibration acceleration, the area near the propeller is tested for three-way vibration to obtain propeller vibration acceleration, the area near the propeller is tested for unidirectional water sound to obtain propeller water sound pressure level, the hull structure is tested for single-item vibration to obtain hull vibration acceleration, the outboard appendage structure is tested for unidirectional water sound to obtain outboard appendage water sound pressure level, and the outboard appendage structure is tested for unidirectional vibration to obtain outboard appendage vibration acceleration.

[0114] Specifically, due to the large number of abnormal noise sources in ship parts, the wide transmission paths, and the complex causes of abnormal noise, the existing abnormal noise processing process generally only measures the working conditions where abnormal noise occurs and the vibration of related parts of the shaft system. There is a problem that incomplete measurement leads to inaccurate analysis and even the source of abnormal noise cannot be found.

[0115] According to the different characteristics of abnormal noise at the stern of a ship, the embodiment of the present invention formulates a tail abnormal noise separation method in a targeted manner, following the following principles:

[0116] First, the measurement point layout should cover the main noise sources at the stern of the ship and their transmission pathways, including the main equipment feet, foundations, pipeline supports, major appendages and structures, shaft support areas, and the vicinity of the propeller. These measurement points can be used to pinpoint the area and scope of abnormal noise generation and impact. Given the complexity of the causes of vibration noise in the propeller shaft system, three measurement points are generally arranged in the X, Y, and Z directions.

[0117] Second, the operating condition design must encompass all operating conditions where abnormal noise may occur and accurately determine how the abnormal noise characteristics change. This typically includes not only the ship's primary sailing conditions but also, for conditions where abnormal noise frequently occurs, appropriately adding other sailing conditions with similar speeds. This operating condition design identifies the scope of abnormal noise occurrence, its characteristics, and its changing patterns.

[0118] Third, it is necessary to combine different state working conditions to ensure that different noise sources can be distinguished. According to the characteristics of the main noise sources at the tail, there are generally three types of working conditions: 1. The main and auxiliary equipment are turned on separately. By turning on and off the main and auxiliary equipment at the stern one by one, the correlation between the abnormal noise source and the main and auxiliary equipment is determined; 2. Parking and taxiing working conditions. Generally, multiple speed parking and taxiing can be set. When a certain feature drops sharply or disappears as the speed decreases during the parking and taxiing process, it means that the phenomenon is obviously related to the propeller shaft system. Through the parking and taxiing working conditions, the correlation between the abnormal noise and the propeller shaft system and the possibility of abnormal noise and flow-excited structures and cavities can be determined. 3. Propeller acceleration test conditions. During the rapid acceleration of the propeller, the uniformity of the flow field around the propeller will change sharply, inducing abnormal noise phenomena, and then the correlation between the abnormal noise and the propeller can be determined. In addition, other working conditions can be appropriately added according to the phenomena and characteristics of abnormal noise generated by each ship, such as steering, release and recovery of outboard devices, etc.; for more complex abnormal tail noise, near-field radiation noise measurement should be added for separation and verification when necessary.

[0119] Specific content and requirements are as follows Figure 2 As shown:

[0120] First, when each main and auxiliary equipment is started and stopped separately, the correlation between each abnormal noise source and each main and auxiliary equipment is determined by turning on and off each main and auxiliary equipment one by one.

[0121] Next, tests were conducted under various design operating conditions. N, M, and L represent the increase or decrease in the X, Y, and Z directions of the ship's shafting speed, respectively. These values create corresponding speed intervals in each direction: [XN, X+N], [YM, Y+M], and [ZL, Z+L]. Shafting speed is measured in revolutions per minute (r / min). N, M, and L can be tailored to the vessel type. For slower-speed vessels, values such as 5, 10, or 20 can be used. During the measurement process, the number of trips can be increased appropriately based on the occurrence of abnormal noise.

[0122] Under the condition of uniform speed and straight flight, the shafting speed increase and decrease test is carried out in the X-axis speed range, the Y-axis speed range and the Z-axis speed range, and the shafting speed at which the abnormal noise appears at the lowest speed, the shafting speed at which the abnormal noise appears at the highest speed and the shafting speed at which the abnormal noise appears frequently are obtained. Figure 2 The shafting speed at which the abnormal noise appears in the X direction is Xr / min, the shafting speed at which the abnormal noise appears most frequently is Yr / min, and the shafting speed at which the abnormal noise appears at the highest is Zr / min.

[0123] Under variable speed conditions, shaft system parking and coasting tests and propeller acceleration tests are carried out respectively. The shaft system parking and coasting here usually refers to the state in which the shaft system and propeller stop running after the main engine power is actively shut down during the process of adjusting the ship's speed, and the ship continues to coast by inertia until the ship speed gradually decays to a standstill.

[0124] Furthermore, by arranging different measuring point positions, measurement parameters of different measuring point types are obtained. The three-dimensional vibration of the shaft support part is tested to obtain the shaft vibration acceleration, the three-dimensional vibration of the area near the propeller is tested to obtain the propeller vibration acceleration, the unidirectional water sound is tested in the area near the propeller to obtain the propeller water sound pressure level, the single vibration of the hull structure is tested to obtain the hull vibration acceleration, the unidirectional water sound is tested on the outboard appendage structure to obtain the outboard appendage water sound pressure level, and the unidirectional vibration of the outboard appendage structure is tested to obtain the outboard appendage vibration acceleration.

[0125] In one embodiment, a ship noise reference database is constructed based on the acoustic characteristics of the ship when there is no abnormal noise corresponding to the multi-dimensional noise test results of the ship, including:

[0126] Collecting the multi-dimensional noise test results of the ship corresponding to different classification test results of the ship delivery test period, the ship use period, the normal test state of the same type of ship and the abnormal test state of the same type of ship;

[0127] The ship noise reference database is composed of test results of different categories.

[0128] It is understandable that according to Figure 2 The process shown in can conduct a relatively comprehensive test on the ship, thereby obtaining a complete set of test results. In order to conduct a more comprehensive analysis of the ship's tail noise, it is necessary to obtain more comprehensive test results from multiple dimensions. Figure 3 As shown, the embodiment of the present invention takes into account the test results of the ship at different periods, including the test results of the ship at the time of delivery and the test results of the ship during use, and also compares the normal test results of ships of the same model and the abnormal test results of ships of the same model to form a complete ship noise reference benchmark database, which is used as the input set for subsequent analysis.

[0129] In one embodiment, based on the ship noise reference database obtained through testing, this embodiment adopts Figure 3 The analytical method for separating abnormal noise at the stern of a ship is shown.

[0130] In the existing tail abnormal noise processing process, the methods of total level, 1 / 3 oct band level and line spectrum analysis are generally used for processing. The above methods can basically determine whether there is abnormal noise at the tail of the ship, but it is difficult to determine the location and cause of the abnormal noise source. The embodiment of the present invention uses the low-frequency array (LOFAR) spectrum analysis method, the detection of envelope modulation on noise (DEMON) spectrum analysis method and the octave analysis method on the basis of total level analysis, 1 / 3 oct band level analysis and line spectrum analysis to analyze the signals of special working conditions and special parts to extract the characteristics of abnormal noise. Among them, the total level analysis is a comprehensive measurement of the overall energy of the signal, without distinguishing the specific frequency band, and directly calculates the sound pressure level or the total value of vibration energy in the full frequency domain; the 1 / 3 oct (one-third octave) band analysis is to divide the frequency range into finer frequency bands according to a geometric progression, and the center frequency of each frequency band satisfies the formula f high / f low = 21 / 3 f high / f Low = 21 / 3, that is, the upper limit frequency of the adjacent frequency band is about 1.26 times the lower limit; line spectrum analysis is to convert the time domain signal into the frequency domain signal through fast Fourier transform to identify discrete linear spectrum components in the spectrum, such as harmonics generated by periodic vibration or electromagnetic interference.

[0131] Specifically, the principles of LOFAR spectrum analysis and DEMON spectrogram analysis are as follows:

[0132] (1) LOFAR spectrum analysis method: the sampling sequence of the original signal is divided into several consecutive segments, each segment sampling points, For any sampling point, we get the variable ; Then, sample each signal segment Normalize and center the variables ; Finally, for the variable Perform a short-time Fourier transform to obtain the LOFAR spectrum.

[0133] (12)

[0134] (13)

[0135] The LOFAR spectrum analysis method constructs a three-dimensional time-frequency diagram of the signal expression by performing a short-time Fourier transform on the sampled data. It can perform joint domain analysis on the signal from both time and frequency perspectives and is suitable for signals with non-stationary characteristics.

[0136] (2) DEMON spectrum analysis method: According to the principle of signal modulation, assuming that the received signal is a periodic local stationary process model, it can be expressed as:

[0137] (14)

[0138] in, is a broadband stationary white Gaussian random process, is the modulation function, and the modulation function can be obtained by using the square demodulation method , and then perform fast Fourier transform on the demodulated signal to obtain the DEMON spectrum of the demodulated signal.

[0139] In the ship tail noise, propeller noise has obvious amplitude modulation, and the modulation frequency is equal to the shaft frequency or propeller blade frequency. The propeller noise can be separated using the DEMON spectrum analysis method.

[0140] According to the different characteristics of the ship's stern noise sources and different working conditions, measurement points, and parameters, the abnormal noise sources at the ship's stern can be separated. The following principles are generally followed during the analysis process:

[0141] First, data analysis should be based on a basic understanding of the acoustic characteristics of the vessel when it is free of abnormal noise. This includes reference to test results of various systems and equipment at delivery, test results collected during operation, and test results of other vessels of the same model. When the inherent characteristics of the propeller and outboard structure are involved, it is also necessary to obtain inherent characteristic parameters such as the propeller's natural frequency and the structural natural frequency.

[0142] Secondly, data analysis is generally carried out in a sequence from simple to complex, from steady-state to unsteady-state conditions: 1. First, data analysis is carried out when the main and auxiliary equipment are turned on and off one by one. If an abnormal noise appears when the equipment is turned on and disappears when it is turned off, and the characteristics are obvious in the equipment feet, base, pipelines and other parts, it means that the equipment has a clear correlation with the abnormal noise. Based on this, the correlation between the main and auxiliary equipment can be preliminarily determined; 2. Then, data analysis of stable direct flight conditions is carried out, including comparison of different measuring points under the same conditions and comparison of the same measuring points under different conditions, to determine the main characteristics, related parts, and change patterns of the abnormal noise; 3. Finally, data analysis of unsteady conditions is carried out to determine the correlation between the abnormal noise and the propeller, shafting and outboard structure.

[0143] Third, data analysis generally follows the principle of coarse to fine, from overall level to line spectrum: 1. First, conduct an overall level comparative analysis of each measuring point under steady-state conditions, generally taking 3dB as the reference benchmark. If the noise exceeds the normal acoustic level by more than 3dB, it is considered that abnormal noise may exist; 2. Conduct a 1 / 3oct analysis on the data with overall level abnormalities to analyze whether there are obvious abnormalities in each frequency band and determine the abnormal frequency band; 3. Conduct line spectrum analysis of each operating condition for the abnormal frequency band, and carry out LOFAR analysis, DEMON analysis and comparative analysis with the inherent characteristics of the propeller and the inherent characteristics of the structure in a targeted manner based on the analysis results. The detailed characteristics and generation mechanism of the abnormal noise are analyzed to obtain the detailed characteristics and generation mechanism of the abnormal noise.

[0144] Correspondingly, we get Figure 3 The analysis process shown is:

[0145] 1. Steady-state operating conditions

[0146] Perform overall level comparison analysis on different measuring points under the same working condition and the same measuring point under different working conditions under steady-state working conditions, and determine overall level abnormal data based on the preset sound pressure level decibel threshold (usually 3DB);

[0147] Perform 1 / 3oct frequency band analysis on the total level abnormal data to determine the abnormal frequency band;

[0148] Conduct line spectrum analysis on abnormal frequency bands to obtain the main characteristics of abnormal noise, abnormal locations and related locations, and the law of abnormal noise changes with speed;

[0149] Based on frequency multiplication analysis and LOFAR spectrum analysis, the main characteristics of abnormal noise, abnormal locations and related locations, and the law of abnormal noise change with ship speed are analyzed. Combined with LOFAR spectrum analysis of the shafting system parking and taxiing under unsteady conditions, the correlation results with the propeller shaft system noise are obtained;

[0150] Compare the abnormal frequency band with the inherent characteristics of the structure of the abnormal part to obtain the noise correlation result with the inherent characteristics of the structure;

[0151] The abnormal frequency band is compared with the inherent characteristics of the propeller to obtain the correlation results with the inherent characteristic noise of the propeller.

[0152] 2. Non-steady-state working conditions

[0153] LOFAR spectrum analysis was performed on the propeller acceleration test under unsteady conditions to obtain the results associated with propeller noise.

[0154] Finally, by combining the above steady-state noise analysis results with the unsteady-state noise analysis results, the bias ratios of the results associated with the propeller shaft system noise, the results associated with the inherent structural characteristics noise, the results associated with the inherent propeller characteristics noise, and the results associated with the propeller noise are generally obtained. The relationship with the inherent structural characteristics is verified, the relationship with the propeller shaft system is clarified, the relationship with the propeller is determined, and the relationship with the inherent propeller characteristics is verified, and the comprehensive noise ratio is calculated. Based on this comprehensive noise ratio, it is possible to clearly identify which specific types of noise have a high proportion, that is, to clarify the main types and causes of abnormal noise, so that the relevant types of noise can be treated in a targeted manner.

[0155] Understandably, abnormal tail noise is often caused by the coupling of multiple factors. Identifying and addressing one factor can temporarily alleviate the problem, but it cannot completely eliminate it. Therefore, when addressing abnormal noise, special attention must be paid to comprehensive and complete analysis. Based on this, in-depth analysis of the causes and mechanisms of each abnormal noise should be conducted to thoroughly resolve it. This avoids superficial investigations, overgeneralizations, and the "blind men touching an elephant" approach.

[0156] The following describes the system for separating abnormal noise sources at the stern of a ship provided by the present invention. The system for separating abnormal noise sources at the stern of a ship described below and the method for separating abnormal noise sources at the stern of a ship described above can refer to each other.

[0157] Figure 4 FIG. 1 is a schematic diagram of a system for separating abnormal noise sources at the stern of a ship according to an embodiment of the present invention. Figure 4 As shown, it includes: an acquisition and construction module 41, a collection module 42, an analysis module 43 and a separation module 44, wherein:

[0158] The acquisition and construction module 41 is used to obtain the multi-dimensional noise test results of the ship, and construct a ship noise reference benchmark database based on the acoustic characteristics of the ship when there is no abnormal noise corresponding to the multi-dimensional noise test results of the ship; the acquisition module 42 is used to use the ship noise reference benchmark database, combined with the navigation characteristics of the ship in the water body, to collect noise source correlation characteristics when the ship is in the start-up and stop states of each main and auxiliary equipment, steady-state conditions and non-steady-state conditions in sequence; the analysis module 43 is used to use a preset combination analysis of the noise source correlation characteristics including total level comparison analysis, 1 / 3oct frequency band analysis, line spectrum analysis, DEMON spectrum analysis, frequency octave analysis and LOFAR spectrum analysis to obtain the correlation results of multiple abnormal noise sources at the rear of the ship; the separation module 44 is used to combine the noise analysis results of the uniform speed straight-line condition and the noise analysis results of the variable speed condition to generate the separation analysis results of the abnormal noise sources at the rear of the ship.

[0159] Figure 5An example of a physical structure diagram of an electronic device is shown below. Figure 5 As shown, the electronic device may include: a processor (processor) 510, a communication interface (Communications Interface) 520, a memory (memory) 530 and a communication bus 540, wherein the processor 510, the communication interface 520, and the memory 530 communicate with each other through the communication bus 540. The processor 510 can call the logic instructions in the memory 530 to execute the method for separating abnormal noise sources at the stern of a ship, which method includes: obtaining a multi-dimensional noise test result of a ship, and constructing a ship noise reference benchmark database based on the acoustic characteristics of the ship when there is no abnormal noise corresponding to the multi-dimensional noise test result of the ship; using the ship noise reference benchmark database, combined with the navigation characteristics of the ship in the water body, in sequence, collecting noise source correlation characteristics when the ship is in the start-up and stop states of each main and auxiliary equipment, steady-state operating conditions and non-steady-state operating conditions; using a preset combination analysis of total level comparison analysis, 1 / 3oct frequency band analysis, line spectrum analysis, DEMON spectrum analysis, frequency octave analysis and LOFAR spectrum analysis on the noise source correlation characteristics to obtain multiple abnormal noise source correlation results at the stern of the ship; determining the comprehensive noise proportion of the multiple abnormal noise source correlation results at the stern of the ship, and generating an abnormal noise source separation analysis result at the stern of the ship.

[0160] Furthermore, the logic instructions in the aforementioned memory 530 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the portion that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a mobile hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0161] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to execute the method for separating abnormal noise sources at the stern of a ship provided by the above-mentioned methods, the method comprising: obtaining a multi-dimensional noise test result of a ship, and constructing a ship noise reference benchmark database based on the acoustic characteristics of the ship when there is no abnormal noise corresponding to the multi-dimensional noise test result of the ship; using the ship noise reference benchmark database, combined with the navigation characteristics of the ship water body, collecting noise source correlation characteristics in sequence when the ship is in the start-up and stop state of each main and auxiliary equipment, steady-state working condition and non-steady-state working condition; using a preset combination analysis of total level comparison analysis, 1 / 3oct frequency band analysis, line spectrum analysis, DEMON spectrum analysis, frequency octave analysis and LOFAR spectrum analysis to analyze the noise source correlation characteristics to obtain multiple ship stern abnormal noise source correlation results; determining the comprehensive noise proportion of the multiple ship stern abnormal noise source correlation results, and generating a ship stern abnormal noise source separation analysis result.

[0162] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0163] Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented using software plus a necessary general-purpose hardware platform, or of course, hardware. Based on this understanding, the essence of the above technical solution, or the portion that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, or an optical disk, and includes a number of instructions for causing a computer device (such as a personal computer, server, or network device) to execute the methods described in each embodiment or certain portions of the embodiments.

[0164] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for separating abnormal noise sources at the stern of a ship, characterized in that: include: Obtaining multi-dimensional noise test results of a ship, and constructing a ship noise reference database based on the acoustic characteristics of the ship when there is no abnormal noise corresponding to the multi-dimensional noise test results of the ship; Using the ship noise reference database and combining the ship's navigation characteristics in water, noise source correlation characteristics are collected in sequence when the ship is in the start-up and stop states of each main and auxiliary equipment, steady-state operating conditions, and unsteady-state operating conditions; The noise source correlation characteristics are analyzed using a preset combination of total level comparison analysis, 1 / 3 octave band analysis, line spectrum analysis, DEMON spectrum analysis, octave analysis, and LOFAR spectrum analysis to obtain the correlation results of multiple abnormal noise sources at the stern of the ship; Determining the comprehensive noise proportions of the correlation results of the multiple abnormal noise sources at the stern of the ship, and generating a separation analysis result of the abnormal noise sources at the stern of the ship; Using the ship noise reference database and combining the ship's navigation characteristics, noise source correlation characteristics are collected in sequence when the ship is in the start-up and stop states of each main and auxiliary equipment, steady-state operating conditions, and unsteady-state operating conditions, including: When each main and auxiliary equipment is started and stopped separately, if any abnormal noise appears when the equipment is turned on and disappears when it is turned off, and has obvious noise characteristics at the preset points of the equipment, then any abnormal noise is determined to be the noise associated with the main and auxiliary equipment; Under steady-state conditions, comparisons are made between different measuring points under the same operating condition and between the same measuring points under different operating conditions to determine the main characteristics, associated locations, and changing patterns of abnormal noise. Under unsteady conditions, determine the correlation between abnormal noise and propeller, shafting and outboard structure; The noise source correlation characteristics are analyzed using a preset combination of total level comparison analysis, 1 / 3 octave band analysis, line spectrum analysis, DEMON spectrum analysis, octave analysis, and LOFAR spectrum analysis to obtain the abnormal noise source separation analysis results at the stern of the ship, including: Perform overall level comparison analysis on different measurement points under the same working condition and the same measurement point under different working conditions under steady-state conditions, and determine overall level abnormal data based on the preset sound pressure level decibel threshold; Performing 1 / 3 oct frequency band analysis on the total level abnormal data to determine the abnormal frequency band; Perform line spectrum analysis on the abnormal frequency band to obtain the main characteristics of the abnormal noise, the abnormal location and related locations, and the law of abnormal noise changes with speed; Based on frequency doubling analysis and DEMON spectrum analysis, the main characteristics of abnormal noise, abnormal locations and related locations, and the law of abnormal noise change with ship speed are analyzed. Combined with LOFAR spectrum analysis of the shafting parking and coasting under the unsteady working condition, the correlation results with the propeller shaft system noise are obtained; Comparing the abnormal frequency band with the inherent structural characteristics of the abnormal part to obtain a noise correlation result with the inherent structural characteristics; Comparing the abnormal frequency band with the inherent characteristics of the propeller to obtain a correlation result with the inherent characteristic noise of the propeller; LOFAR spectrum analysis is performed on the propeller acceleration test under the unsteady state condition to obtain results associated with propeller noise.

2. The method for separating abnormal noise sources at the stern of a ship according to claim 1, characterized in that: Obtaining a multi-dimensional noise test result of a ship, and constructing a ship noise reference database based on the acoustic characteristics of the ship when there is no abnormal noise according to the multi-dimensional noise test result of the ship, further comprising: Obtain the time sensitivity and condition dependence of abnormal ship noise, and collect users' overall judgment information on noise; According to different ship types, stern structures and design features, determine the noise sources and related influencing factors at the stern of the ship, and obtain the ship design parameters and usage records; Based on the structural vibration theory, shafting torsional vibration theory and propeller noise generation excitation principle, the characteristic differences and correlations of various noise sources are determined.

3. The method for separating abnormal noise sources at the stern of a ship according to claim 2, characterized in that: Obtain multi-dimensional ship noise test results, including: Determine the ship's operating condition design, measurement point layout, and measurement parameters based on the type of noise source at the ship's stern. The operating condition design includes separate start and stop of each main and auxiliary engine, a constant speed straight-through test condition, and a variable speed condition. The measurement point layout includes measurement point location and measurement point type. The measurement parameters include vibration acceleration and underwater sound pressure. When each main and auxiliary equipment is started and stopped separately, the correlation between each abnormal noise source and each main and auxiliary equipment is determined by turning on and off each main and auxiliary equipment one by one; Under the uniform speed straight-line test condition, the shafting speed increase and decrease tests are performed on the X, Y, and Z axis speeds of the shafting speed in the X axis speed range, the Y axis speed range, and the Z axis speed range, respectively, to obtain the shafting speed at which the abnormal noise occurs at the lowest speed, the shafting speed at which the abnormal noise occurs at the highest speed, and the shafting speed at which the abnormal noise occurs frequently; Under the variable speed conditions, a shafting parking and taxiing test and a propeller acceleration test are respectively performed; The measuring point positions include a shafting support part, an area near the propeller, a hull structure and an outboard appendage structure. The shafting support part is tested for three-way vibration to obtain shafting vibration acceleration, the area near the propeller is tested for three-way vibration to obtain propeller vibration acceleration, the area near the propeller is tested for unidirectional water sound to obtain propeller water sound pressure level, the hull structure is tested for single-item vibration to obtain hull vibration acceleration, the outboard appendage structure is tested for unidirectional water sound to obtain outboard appendage water sound pressure level, and the outboard appendage structure is tested for unidirectional vibration to obtain outboard appendage vibration acceleration.

4. The method for separating abnormal noise sources at the stern of a ship according to claim 3, characterized in that: According to the acoustic characteristics of the ship without abnormal noise corresponding to the multi-dimensional noise test results of the ship, a ship noise reference database is constructed, including: Collecting the multi-dimensional noise test results of the ship corresponding to different classification test results of the ship delivery test period, the ship use period, the normal test state of the same type of ship and the abnormal test state of the same type of ship; The ship noise reference database is composed of test results of different categories.

5. The method for separating abnormal noise sources at the stern of a ship according to claim 1, characterized in that: Determining the comprehensive noise proportion of the correlation results of the multiple abnormal noise sources at the rear of the ship, and generating a separation analysis result of the abnormal noise sources at the rear of the ship, including: Respectively obtaining the result of correlation with the propeller shaft system noise, the result of correlation with the inherent structural characteristic noise, the result of correlation with the inherent propeller characteristic noise, and the deflection ratio of the result of correlation with the propeller noise, and calculating the comprehensive noise proportion; Based on the comprehensive noise proportion, the abnormal noise source separation analysis result of the ship stern is output.

6. A system for separating abnormal noise sources at the stern of a ship, based on the method for separating abnormal noise sources at the stern of a ship according to any one of claims 1 to 5, characterized in that: include: An acquisition and construction module is used to obtain a ship multi-dimensional noise test result, and construct a ship noise reference database based on the acoustic characteristics of the ship when there is no abnormal noise corresponding to the multi-dimensional noise test result of the ship; An acquisition module is used to use the ship noise reference database and, in combination with the ship's navigation characteristics in water, collect noise source correlation characteristics in sequence when the ship is in the start-up and stop states of each main and auxiliary equipment, steady-state operating conditions, and unsteady-state operating conditions; An analysis module is used to analyze the noise source correlation characteristics using a preset combination of overall level comparison analysis, 1 / 3 octave band analysis, line spectrum analysis, DEMON spectrum analysis, octave analysis, and LOFAR spectrum analysis to obtain correlation results of multiple abnormal noise sources at the stern of the ship; The separation module is used to determine the comprehensive noise proportion of the correlation results of the multiple abnormal noise sources at the rear of the ship, and generate a separation analysis result of the abnormal noise sources at the rear of the ship.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method for separating abnormal noise sources at the stern of a ship as described in any one of claims 1 to 5 is implemented.

8. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for separating abnormal noise sources at the stern of a ship as claimed in any one of claims 1 to 5 is implemented.

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