Ice-induced vibration and underwater noise test device and test method

Abstract

The invention provides an ice-induced vibration and underwater noise test device and a test method, belongs to the field of vibration and noise reduction of an icebreaker, and solves the problem that the consistency of statistical energy analysis load input and an ice load simulation result cannot be ensured by an existing method. The device comprises a vibration exciter which is arranged on a ship body scale model and is used for simulating icebreaking impact load exciting force; the acceleration sensors are distributed on the ship body scale model and are used for measuring the vibration response of the ship body scale model; the hydrophone is arranged in a water body on the outer side of the ship body scaling model; the mimicry plate is laid on the surface of a water body outside the ship body scale model and is used for simulating an ice layer and reflecting noise; and the data processing unit is used for collecting and processing data of the acceleration sensor and the hydrophone, and the data is compared with simulation data in the computer. The method is used for verifying the effectiveness of an ice-induced impact load simplification method of the icebreaker and verifying the effectiveness of a multi-point energy average loading mode.

Description

Technical Field

[0001] The invention belongs to the field of vibration and noise reduction of icebreakers, and in particular relates to an ice-induced vibration and underwater noise test device and a test method. Background Art

[0002] For ice loads, existing studies mostly obtain icebreaker icebreaking impact excitation through numerical simulation, simplify the processing by arithmetic averaging, and verify the effectiveness of ice load simplification methods through numerical simulation, which is not enough to support engineering applications. For the prediction of medium and high frequency underwater noise, existing studies are mostly based on statistical energy methods, but the input of this method is the energy average of a certain scale of plate and shell subsystems, while the ice loads in numerical simulations or experimental tests are nodal forces. Generally, the energy average of nodal forces of a certain range of plate and shell subsystems is used to process the ice loads of medium and high frequency underwater noise, but there is still a lack of experimental verification at this stage.

[0003] In summary, an ice-induced vibration and underwater noise test device and test method are proposed to verify the effectiveness of the simplified method of ice-induced impact load on icebreakers and the effectiveness of the multi-point energy average loading method. Summary of the invention

[0004] In view of this, an ice-induced vibration and underwater noise test device and test method are proposed, which solves the problem that the existing method cannot ensure the consistency between the statistical energy analysis load input and the ice load simulation results, verifies the effectiveness of the simplified method of icebreaker ice-induced impact load and verifies the effectiveness of the multi-point energy averaging loading method.

[0005] To achieve the above object, the present invention adopts the following technical solution: According to one aspect of the present invention, there is provided an ice-induced vibration and underwater noise test device, comprising:

[0006] The exciter is set on the scaled model of the hull to simulate the excitation force of the icebreaking impact load;

[0007] A plurality of acceleration sensors are provided and distributed on the scaled-down model of the hull, and are used to measure the vibration response of the scaled-down model of the hull;

[0008] A plurality of hydrophones are provided and arranged in the water outside the scaled-down model of the hull, and are used to receive the radiated noise generated by the vibration of the scaled-down model of the hull;

[0009] Mimicking plates are laid on the water surface outside the scaled model of the hull to simulate ice and reflect noise;

[0010] The data processing unit is used to collect and process the data of the acceleration sensor and the hydrophone, and the data is compared and processed with the simulation data in the computer.

[0011] Furthermore, the exciter is fixedly arranged on the inner side of the bow of the scaled-down model of the hull, and the exciter includes an exciting rod connected to the bow outer shell, and an excitation point is formed at the connection.

[0012] Furthermore, the acceleration sensor is arranged at positions including a single-side bulwark inside the scaled-down model of the hull, an internal bottom plate of the scaled-down model of the hull, and near the excitation point.

[0013] Furthermore, the acceleration sensor is magnetically attracted inside the scaled model of the hull.

[0014] Furthermore, a plurality of the hydrophones are arranged below the longitudinal section and outside the bulwarks on both sides of the scaled model of the hull.

[0015] Furthermore, the plurality of hydrophones are arranged at the same depth.

[0016] Furthermore, the mimicry plate is an aluminum plate.

[0017] Furthermore, the aluminum plates are laid on the bow, port side and starboard side of the scaled-down model of the hull to simulate the reflection effect of the ice surface on the underwater noise of the hull.

[0018] Furthermore, the data processing unit includes a signal collector, a signal conditioner and a computer. The acceleration signal measured by the acceleration sensor is transmitted to the signal collector via the signal conditioner and recorded by the computer.

[0019] According to a second aspect of the present invention, a method for testing ice-induced vibration and underwater noise is provided, using an ice-induced vibration and underwater noise test device, and the specific steps are as follows:

[0020] The exciter generates an excitation force acting on the scaled-down model of the hull, and the scaled-down model of the hull vibrates to generate radiated noise;

[0021] The acceleration sensor measures the vibration acceleration signal and transmits it to the signal collector through the signal conditioner, and the computer records the data;

[0022] The hydrophone measures the underwater radiated sound power signal, which is then stored in the computer after passing through the signal collector;

[0023] Spectrum analysis: The acceleration value obtained by the vibration acceleration sensor is a time domain acceleration curve, and the amplitude-frequency curve of acceleration can be obtained through fast Fourier transform.

[0024] Through simulation comparative analysis, a statistical energy analysis model of the hull is established, the underwater radiation noise is obtained by simulation calculation, and the numerical simulation results at the same position are compared with the model test results; it is used to verify the feasibility of conducting underwater radiation noise analysis of the hull based on the statistical energy analysis method, the effectiveness of the simplified method of ice-induced impact load on the hull, and the effectiveness of multi-point energy average loading.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: by setting acceleration sensors and hydrophones at multiple points to detect vibration and noise, and comparing them with the results of simulation analysis, the effectiveness of the simplified method for icebreaker ice impact loads and the effectiveness of the multi-point energy averaging loading method are verified. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0027] Figure 1 It is the overall structure diagram of the present invention;

[0028] Figure 2 A flow chart of the present invention of the present invention;

[0029] Figure 3 It is a schematic diagram of the excitation of the vibration exciter of the present invention;

[0030] Figure 4 It is a front view schematic diagram of the arrangement of the vibration acceleration sensor of the present invention;

[0031] Figure 5 A schematic top view of the arrangement of the vibration acceleration sensor of the present invention;

[0032] Figure 6 It is a layout diagram of the hydrophone of the present invention;

[0033] Figure 7 It is an exploded diagram of the hull scaled statistical energy analysis model of the present invention;

[0034] Figure 8 It is a schematic diagram of the semi-infinite domain test points of the hull scaled model of the present invention;

[0035] Fig. 9 The comparison between the simulation and test sound pressure levels under fixed frequency excitation of the present invention;

[0036] Fig.10 This is a comparison diagram of the vibration acceleration levels of the reduced-scale model before and after simplification of the 2s time history load of the present invention;

[0037] Fig.11 This is a comparison diagram of underwater radiated noise sound pressure levels before and after 2s load simplification of the present invention;

[0038] Fig.12 This is a comparison diagram of the vibration acceleration of each measuring point before and after the 5s time history load simplification of the present invention;

[0039] Fig.13 This is a comparison diagram of underwater radiated noise sound pressure levels before and after 5s load simplification of the present invention;

[0040] Fig.14 This is a comparison chart of the effectiveness of multi-point energy average loading methods.

[0041] In the figure: a scaled model of a ship 1; a vibrator 2; an acceleration sensor 3; a hydrophone 4; a data processing unit 5; a signal collector 6; a signal conditioner 7; and a computer 8. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict, and the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0043] It should be noted that the descriptions of the present invention regarding directions such as "left", "right", "left side", "right side", "upper", "lower", "top", and "bottom" are all defined based on the relationship between the orientations or positions shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the structure must be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention. In the description of the present invention, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0044] In the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. Specific implementation method one:

[0046] Referring to the accompanying drawings, this embodiment is described, providing an ice-induced vibration and underwater noise test device, comprising:

[0047] The exciter 2 is arranged on the scaled model of the ship hull and is used to simulate the excitation force of the icebreaking impact load;

[0048] Acceleration sensors 3, which are provided in plurality and distributed on the scaled-down model of the hull, are used to measure the vibration response of the scaled-down model of the hull;

[0049] A plurality of hydrophones 4 are arranged in the water outside the scaled-down model of the hull, and are used to receive the radiated noise generated by the vibration of the scaled-down model of the hull;

[0050] Mimicking plates are laid on the water surface outside the scaled model of the hull to simulate ice and reflect noise;

[0051] The data processing unit 5 is used to collect and process the data of the acceleration sensor 3 and the hydrophone 4. The data is compared and processed with the simulation data in the computer.

[0052] The vibrator 2 vibrates at a set frequency, driving the scaled model of the hull to vibrate, the acceleration sensor 3 and the hydrophone 4 receive signals, and the data processing unit 5 receives and processes the data and sends it to the computer for simulation comparison. The mimic board is an aluminum plate, laid on the bow, port and starboard, simulating the reflection effect of the ice surface on the underwater noise of the hull.

[0053] In this embodiment, the exciter 2 is fixedly arranged inside the bow of the scaled model of the ship hull, and the exciter 2 includes an excitation rod connected to the bow shell, and the connection forms an excitation point. The excitation rod of the exciter 2 vibrates and acts on the excitation point.

[0054] In this embodiment, the acceleration sensor 3 is arranged at a location including a single-side bulwark inside the scaled-down model of the hull, an internal bottom plate of the scaled-down model of the hull, and near the excitation point.

[0055] The adsorption position of the acceleration sensor 3 is required to reflect the vibration characteristics of the test model. To ensure that the acceleration sensor 3 can collect data well, the surface of the model should be cleaned before adsorption to ensure smoothness. The cables of the acceleration sensor 3 should be bundled and extended from one side of the model to the signal acquisition system. Acceleration sensors 3 are evenly arranged on one side of the scaled model of the hull from the stern bulkhead along the bow direction, with a total of 9 arranged; 8 sensors are arranged on the bottom plate of the ship, and acceleration sensors 3 are arranged around the bow excitation point.

[0056] In this embodiment, the acceleration sensor 3 is magnetically attracted inside the scaled model of the ship hull.

[0057] In this embodiment, the hydrophones 4 are arranged below the longitudinal section and outside the bulwarks on both sides of the scaled model of the hull.

[0058] In this test, a hydrophone 4 is arranged at a depth of 0.5m directly below the scaled model of the hull, in the middle longitudinal section every 0.6m along the length of the ship, with a total of 5 hydrophones 4 arranged; on both sides of the scaled model at a depth of 0.5m from the side of the longitudinal section, a hydrophone 4 is arranged every 0.75m along the length of the ship, with a total of no less than 10 hydrophones 4 on both sides.

[0059] The hydrophone 4 is suspended and is lowered to a certain depth underwater and fixed during the test.

[0060] In this embodiment, the hydrophones 4 are arranged at the same depth.

[0061] In this embodiment, the mimicking plate is an aluminum plate.

[0062] In this embodiment, the aluminum plates are laid on the bow, port side and starboard side of the hull scale model 1 to simulate the reflection effect of the ice surface on the underwater noise of the hull.

[0063] In this embodiment, the data processing unit 5 includes a signal collector 6, a signal conditioner 7 and a computer 8. The acceleration signal measured by the acceleration sensor 3 is transmitted to the signal collector 6 via the signal conditioner 7 and recorded by the computer 8. Specific implementation method 2:

[0065] A method for testing ice-induced vibration and underwater noise, using an ice-induced vibration and underwater noise testing device, specifically comprising the following steps:

[0066] In step S101, the exciter 2 generates an excitation force acting on the scaled-down model of the hull, and the scaled-down model of the hull vibrates to generate radiated noise;

[0067] In step S102, the acceleration sensor 3 measures the vibration acceleration signal and transmits it to the signal collector through the signal conditioner, and the computer records the data;

[0068] In step S13, the hydrophone 4 measures the underwater radiated sound power signal, which is stored in the computer after passing through the signal collector;

[0069] In step S104, spectrum analysis is performed, and the acceleration value obtained by the vibration acceleration sensor 3 is a time domain acceleration curve, and the amplitude-frequency curve of the acceleration can be obtained through fast Fourier transformation;

[0070] In step S105, simulation comparison and analysis are performed, a statistical energy analysis model of the hull is established, underwater radiation noise is obtained by simulation calculation, and the numerical simulation results at the same position are compared with the model test results; this is used to verify the feasibility of conducting underwater radiation noise analysis of the hull based on the statistical energy analysis method, the effectiveness of the simplified method of ice-induced impact loads on the hull, and the effectiveness of multi-point energy average loading.

[0071] The working condition of 3kn speed and 1m ice thickness was selected, and the test sampling frequency was 20kHz. The acceleration value obtained by the vibration acceleration sensor 3 is the time domain acceleration curve. The amplitude-frequency curve of the acceleration can be obtained through fast Fourier transform. The method of transforming the time domain signal into the frequency domain for analysis is called spectrum analysis. The purpose of spectrum analysis is to decompose the complex time history waveform into several single harmonic components through Fourier transform to obtain the frequency structure of the signal and the harmonic and phase information. The Fourier transform formula is:

[0072]

[0073] In the test, an exciter is used to excite the typical position of the structure. During the test, the vibration acceleration sensor is adsorbed on the surface of the test piece using a magnetic base. The vibration acceleration signal at the measuring point is transmitted to the data acquisition instrument through the signal line. The data acquisition system is then used to perform spectrum analysis to obtain the vibration response spectrum at the measuring point, and then the total level is obtained. The vibration acceleration level at the measuring point is obtained by the following formula:

[0074] L k =20lg(a i / a0)

[0075] Among them, a i It indicates the vibration acceleration amplitude of the measuring point, a0 indicates the vibration acceleration reference value, and in this test, a0=1e - 6 m / s 2 .

[0076] The total vibration acceleration level at a certain measuring point is obtained by the following formula:

[0077]

[0078] Where L k It represents the vibration acceleration level at the center frequency of the kth frequency band in the 1 / 3 octave of the measuring point. Its value is obtained according to the following formula:

[0079]

[0080] where a n represents the amplitude of the spectrum in the kth frequency band, k min represents the lower cutoff frequency of the kth frequency band, k max represents the upper cutoff frequency of the kth frequency band, a ref As the benchmark value, this test takes a ref =1e -6 m / s 2 .

[0081] The sound pressure level is calculated as follows:

[0082] L p =20lg(P / P0)

[0083] Where P is the sound pressure, P0 is the reference sound pressure, and the reference sound pressure in water is taken as 1e -6 Pa, L p is the sound pressure level.

[0084] First, a statistical energy analysis model of the hull is established. Figure 7 As shown in the figure, the sound field test point is 0.5 meters from the center of the hull and 100 meters from the vertical center plane of the ship. Figure 8 shown.

[0085] In order to verify the effectiveness of the statistical energy analysis method of the scaled-down hull model, a fixed-frequency signal is used as input. By applying a fixed-frequency excitation to the icebreaking impact part of the bow of the scaled-down hull model, the underwater radiated noise is obtained by simulation calculation. The numerical simulation results at the same position are compared with the model test results. The comparison curves at different frequency points are shown in Figure 2. Fig. 9 .

[0086] From the comparison data of the numerical simulation and experimental test of the underwater noise of the scaled-down hull model under various fixed-frequency excitations, it can be seen that the two are consistent in trend, the radiation noise responses under various excitation frequencies are in good agreement, and there are certain deviations in the responses of individual frequencies, which verifies the feasibility of conducting underwater radiation noise analysis of the hull based on the statistical energy analysis method.

[0087] Comparative analysis of icebreaking impact vibration and noise test results before and after load simplification. Take a 2-second and 5-second load after stable icebreaking for time domain load simplification, and use the icebreaking impact load before and after simplification as input. Based on multi-channel collaborative vibration and noise control technology, icebreaking impact vibration and noise tests before and after load simplification are carried out. Considering the frequency band requirements for hull impact vibration and noise analysis, the test sampling frequency is 20kHz, and multiple icebreaking impact loads before and after simplification are applied. After taking the average value, the comparison of the structural vibration and underwater radiation noise response of the hull scaled model before and after load simplification can be obtained.

[0088] Comparison of vibration acceleration at each measuring point before and after 2-second time history load simplification. Fig.10 From the comparison of the acceleration of each vibration measuring point before and after the load simplification, it can be seen that the vibration acceleration response of the hull scaled model after the load simplification is in good agreement with that before the simplification. The two maintain good consistency in both trend and magnitude, which verifies the effectiveness of the icebreaking impact load simplification method in this study.

[0089] The sound pressure of each measuring point before and after the 2-second time history load simplification is compared. Based on the verification of the simplified method of impact vibration of the hull scale model mentioned above, the effectiveness of the simplified method of icebreaking impact load is further verified by taking the radiation sound pressure of each underwater acoustic assessment point as the evaluation index for underwater radiation noise. The specific comparison results are shown in Fig.11 , where the left column is the line spectrum of the sound pressure level at the 4 measuring points of the hydrophone, and the right column is its one-third octave band.

[0090] Comparison of vibration acceleration at each measuring point before and after 5-second time history load simplification, and comparison of the total level of vibration acceleration at each measuring point Fig.12 ; Comparison of sound pressure at each measuring point before and after 5-second time history load simplification Fig.13 , the left column is the line spectrum of sound pressure level at 4 measuring points of the hydrophone, and the right column is its one-third octave band diagram.

[0091] From the comparison of icebreaking impact vibration acceleration and underwater radiation noise at each measuring point before and after simplification of different time history curve loads, it can be seen that whether it is 2-second time history curve simplification or 5-second time history curve simplification, the vibration acceleration and underwater noise at each measuring point of the hull scale model maintain a high consistency, meeting the index requirements, verifying the effectiveness of the simplification method of hull ice-induced impact loads.

[0092] like Fig.14 As shown in the figure, the multi-point energy average loading effectiveness test verification, based on the above test verification, in order to verify the effectiveness of the multi-point energy average loading method of the hull, according to the design drawings of the hull scaled model, the hull underwater noise statistical energy analysis model was established, the excitation position area is located in an arc plate at the bow of the hull, and the measuring points 1, 2, and 3 are evenly distributed in the plate, which is consistent with the statistical energy excitation force loading plate shell subsystem. When the load is loaded, the vibration acceleration response of measuring points 1, 2, and 3 at the excitation point position of the bow of the scaled model is averaged to obtain the average vibration energy of the plate, and then the average vibration energy is used as input to load the bow plate shell subsystem of the statistical energy analysis model to carry out the calculation of the underwater noise of the hull scaled model. The assessment point is also 100 meters away from the vertical center plane of the ship, and the far-field radiation noise of the hull scaled model is calculated, and according to the energy attenuation law of the free sound field, the sound source level data of the underwater noise radiation noise of the hull is converted.

[0093] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. An ice-induced vibration and underwater noise test device, characterized in that: include: An exciter (2) is arranged on the scaled-down model of the ship hull (1) and is used to simulate the excitation force of the icebreaking impact load; A plurality of acceleration sensors (3) are provided and distributed on the scaled-down model of the ship hull, and are used to measure the vibration response of the scaled-down model of the ship hull (1); A plurality of hydrophones (4) are arranged in the water outside the scaled-down model of the ship hull and are used to receive radiated noise generated by vibration of the scaled-down model of the ship hull (1); Mimicking plates are laid on the water surface outside the scaled model of the hull to simulate ice and reflect noise; The data processing unit (5) is used to collect and process data from the acceleration sensor (3) and the hydrophone (4), and the data is compared and processed with simulation data in a computer (8).

2. The ice-induced vibration and underwater noise testing device according to claim 1, characterized in that: The vibrator (2) is fixedly arranged on the inner side of the bow of the scaled-down model of the hull, and the vibrator (2) comprises a vibrator rod connected to the outer shell of the bow, and an excitation point is formed at the connection.

3. The ice-induced vibration and underwater noise testing device according to claim 1, characterized in that: The acceleration sensor (3) is arranged at positions including a single-side bulwark inside the scaled-down model of the hull, a bottom plate inside the scaled-down model of the hull, and near the excitation point.

4. The ice-induced vibration and underwater noise testing device according to claim 3, characterized in that: The acceleration sensor (3) is magnetically attracted inside the scaled-down model of the ship hull.

5. The ice-induced vibration and underwater noise testing device according to claim 1, characterized in that: A plurality of hydrophones (4) are arranged below the longitudinal section and outside the bulwarks on both sides of the scaled model of the hull.

6. The ice-induced vibration and underwater noise testing device according to claim 5, characterized in that: The plurality of hydrophones (4) are arranged at the same depth.

7. The ice-induced vibration and underwater noise testing device according to claim 1, characterized in that: The mimicry plate is an aluminum plate.

8. The ice-induced vibration and underwater noise testing device according to claim 7, characterized in that: The aluminum plates are laid on the bow, port side and starboard side of the hull scale model (1) to simulate the reflection effect of ice on the underwater noise of the hull.

9. The ice-induced vibration and underwater noise testing device according to claim 1, characterized in that: The data processing unit (5) comprises a signal collector (6), a signal conditioner (7) and a computer (8); the acceleration signal measured by the acceleration sensor (3) is transmitted to the signal collector (6) via the signal conditioner (7) and recorded by the computer (8).

10. A method for testing ice-induced vibration and underwater noise, characterized in that: Using the ice-induced vibration and underwater noise test device as described in any one of claims 1 to 9, the specific steps are: The exciter (2) generates an excitation force acting on the scaled-down model of the ship hull (1), and the scaled-down model of the ship hull (1) vibrates to generate radiated noise; The acceleration sensor (3) measures the vibration acceleration signal and transmits it to the signal collector (6) through the signal conditioner, and the computer (8) records the data; The hydrophone (4) measures the underwater radiated sound power signal, which is stored in the computer (8) after passing through the signal collector; Spectrum analysis: the acceleration value obtained by the vibration acceleration sensor (3) is a time domain acceleration curve, and the amplitude-frequency curve of the acceleration can be obtained through fast Fourier transform; Simulation comparison and analysis, establish the hull statistical energy analysis model, simulate and calculate the underwater radiation noise, and compare the numerical simulation results with the model test results at the same location; It is used to verify the feasibility of conducting underwater radiation noise analysis of the hull based on the statistical energy analysis method, and to verify the effectiveness of the simplified method of ice-induced impact load on the hull and the effectiveness of multi-point energy average loading.

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