Frequency sweeping method for measuring sound transmission characteristic frequency of sea pipeline system

Abstract

The embodiment of the invention provides a frequency sweep method for measuring sound transfer characteristic frequency of a Kingston pipeline system, which comprises the following steps of: completing frequency sweep of the Kingston system by taking a pump set as a leaf frequency sound source based on frequency conversion control of the pump set to obtain a leaf frequency; indirectly testing the sound transmission response level of the pipeline system to obtain the vibration acceleration level of the pipeline interface flange monitoring point; and based on the common working condition range of the Kingston system, determining the sound transmission characteristic frequency of the pipeline system according to the blade frequency obtained by the sweep frequency test and the vibration acceleration level of the pump and pipeline interface flange monitoring point. According to the method, the configuration, arrangement and trend of an actual pipeline system and pipeline accessories such as a heat exchanger, a filter, a silencer, a valve and an elbow contained in the system can be considered, the sound transmission characteristic frequency of the pipeline system is accurately identified, and the blade frequency in the common working condition range of a pump set is kept away from the sound transmission characteristic frequency of the pipeline system through design; and technical support is provided for noise control of a Kingston system.

Description

Technical Field

[0001] The invention relates to the technical field of ship machinery noise control, in particular to a frequency sweeping method for measuring the acoustic transmission characteristic frequency of a sea-going pipeline system. Background Art

[0002] The noise of the ship's sea-going system, especially the line spectrum flow noise of the pump blade frequency, is an important source of the ship's overall underwater noise. The line spectrum flow noise of the pump blade frequency is transmitted in the fluid medium inside the pipeline. When the acoustic design of the sea-going system is not good, the frequency of the pump blade frequency coincides with the natural frequency characteristics of the sound transmission of the pipeline system itself. The energy of the single blade line spectrum underwater noise radiated at the sea mouth accounts for nearly 30% of the total underwater noise energy, seriously affecting the overall acoustic performance.

[0003] In view of this, in order to control the blade frequency line spectrum noise of the Tonghai system, researchers at home and abroad have done a lot of research work, studying the generation, transmission, radiation and noise reduction control of blade frequency line spectrum noise. The representative results are mainly:

[0004] (1) Surface sound source method of pump blade frequency noise based on acoustic analogy

[0005] This method is based on the high-precision simulation of the turbulent flow field of the pump impeller, extracts the pulsating hydrodynamic pressure of the blade flow surface, and establishes the blade frequency line spectrum flow noise generation surface through the acoustic analogy theory. It can accurately simulate the intensity of the pump impeller blade frequency line spectrum noise source, and provides technical support for the establishment of simplified models of various blade frequency line spectrum noise sources. However, this method only solves the problem of sound source modeling of the Tonghai system. The transmission analysis of the pipeline system flow noise also needs to consider the coupling of the sound source and the pipeline system as a whole.

[0006] (2) Analysis method of acoustic transmission characteristics of sea pipeline system

[0007] The blade frequency of the pump group in the sea-going system is usually not higher than 300Hz, which is generally lower than the first-order medium frequency of the acoustic transmission of the pipeline system. Therefore, it can only excite the plane wave of the pipeline. In fact, affected by the structural elasticity of the pipeline itself, the pump group blade frequency excites the pipeline to produce a plane-like sound transmission along the fluid medium. Other high-order sound waves are limited by the exponential attenuation law and often contribute little to the underwater radiation noise. At present, the acoustic analysis results of the pipeline system based on the plane wave theory show that the process of the pipeline system itself transmitting plane waves has typical filtering characteristics for plane waves. The pipeline has high passability for plane waves at a series of frequency points. These frequencies are the characteristic frequencies of pipeline sound transmission. However, at this stage, the calculation and evaluation of the characteristic frequencies of acoustic transmission of the pipeline system are limited to straight pipelines or pipeline systems with a small number of simple pipeline accessories (90° elbows). The calculation accuracy of the characteristic frequencies of acoustic transmission for complex pipeline systems on real ships (including heat exchangers, mufflers, valves, filters and other pipeline accessories that are difficult to accurately model) is not enough.

[0008] (3) Blade frequency line spectrum silencing technology of Tonghai system

[0009] The technology of sea-going pipeline silencer has been developed for a long time. The current mainstream silencers are all based on airbag structures, which can take into account both line spectrum and broadband silencer, and can improve the frequency control effect by adjusting the airbag pressure for specific frequencies. Nevertheless, when the sound transmission characteristic frequency of the pipeline system with the silencer installed coincides with the blade frequency of the pump group, a very strong line spectrum noise problem is still generated. Summary of the invention

[0010] In view of the above-mentioned problems existing in the prior art, an embodiment of the present invention provides a frequency sweeping method for measuring the characteristic frequency of sound transmission of a sea-going pipeline system. The method can take into account the configuration, layout, and direction of the actual pipeline system, as well as the heat exchangers, filters, mufflers, valves, elbows and other pipeline accessories contained in the system itself, and accurately identify the characteristic frequency of sound transmission of the pipeline system. By design, the blade frequency within the common operating range of the pump group and the characteristic frequency of sound transmission of the pipeline system are avoided, thereby providing technical support for noise control of the sea-going system.

[0011] The embodiment of the present invention provides a frequency sweeping method for measuring the acoustic transmission characteristic frequency of a sea pipeline system, comprising:

[0012] Based on the variable frequency control of the pump group, the frequency sweep of the Tonghai system is completed with the pump group as the blade frequency sound source to obtain the blade frequency;

[0013] Conduct indirect test on the acoustic transmission response level of the pipeline system to obtain the vibration acceleration level of the pipeline interface flange monitoring point;

[0014] Based on the common operating range of the Tonghai system, the characteristic frequency of acoustic transmission of the pipeline system is determined according to the blade frequency obtained by the sweep frequency test and the vibration acceleration level of the flange monitoring point of the pump and pipeline interface.

[0015] In some embodiments of the present invention, the frequency sweeping of the sea communication system is completed based on the variable frequency control of the pump group and the pump group is used as the blade frequency sound source, including:

[0016] Control the pump unit variable frequency starter of the Tonghai system that is fully installed and can operate normally to start the Tonghai pump unit to the rated operating condition, reduce the pump unit to the lowest speed condition within the common operating range of the Tonghai system and operate stably, and record the flow rate Q0 and speed n0 of the pump unit under this condition;

[0017] According to the minimum adjustable frequency interval Δf of the frequency converter output frequency min , so that the output frequency increases by Δf min , control the pump group to increase the speed and run stably, ensure the acoustic state of the pump group is stable, and record the flow rate Q1 and speed n1 of the pump group under the current working condition;

[0018] Repeat the above process to continuously control the pump group to gradually increase the speed from the lowest speed condition to the highest speed condition n N , traverse the common operating range of the Tonghai system, and obtain a series of pump group flow rates Q i , speed n i , where i is any integer from 0 to N. So far, the frequency sweep of the Tonghai system is completed with the pump group as the blade frequency sound source.

[0019] In some embodiments of the present invention, the indirect test of the acoustic transmission response level of the pipeline system includes:

[0020] Within the common operating range of the Tonghai system, for each frequency sweep operating speed n i , keep the pump group running for the set time, after the acoustic state of the seawater pump is stable, use a single vibration sensor to monitor the vibration of the interface flange structure between the pump group and the pipeline, and record the blade frequency point f i =n i B / 60 vibration acceleration level Where i is any integer from 0 to N, B is the number of blades;

[0021] The vibration acceleration level indirectly reflects the acoustic response level caused by the pump blade frequency flow noise inside the pipeline system.

[0022] In some embodiments of the present invention, the method of determining the acoustic transmission characteristic frequency of the pipeline system based on the common operating range of the sea-connected system and the blade frequency obtained by the sweep frequency test and the vibration acceleration level of the flange monitoring point of the pump and pipeline interface includes:

[0023] Corresponding to the common operating range of the Tonghai system, the pump group blade frequency-flange vibration monitoring point vibration level curve is drawn based on the blade frequency obtained by the sweep frequency test and the vibration acceleration level of the flange monitoring point of the pump and pipeline interface.

[0024] In some embodiments of the present invention, in the process of determining the acoustic transmission characteristic frequency of the pipeline system according to the blade frequency obtained by the sweep frequency test and the vibration acceleration level of the monitoring point of the pump and pipeline interface flange,

[0025] As the speed of the pump unit increases, the blade frequency vibration level of the pump unit flange tends to increase with the increase of speed.

[0026] In some embodiments of the present invention, in the process of determining the acoustic transmission characteristic frequency of the pipeline system according to the blade frequency obtained by the sweep frequency test and the vibration acceleration level of the monitoring point of the pump and pipeline interface flange, the sweep frequency method further includes:

[0027] In the frequency sweep range, when the leaf frequency f i The characteristic frequency f of the acoustic transmission of the pipeline system p coincidence, i.e., f i =fp When , the curve shows an obvious peak at this frequency point, proving that the pipeline system has a characteristic frequency of sound transmission within the frequency range of the sweep, and the characteristic frequency is numerically equal to the peak frequency.

[0028] In some embodiments of the present invention, in the process of determining the acoustic transmission characteristic frequency of the pipeline system according to the blade frequency obtained by the sweep frequency test and the vibration acceleration level of the monitoring point of the pump and pipeline interface flange, the sweep frequency method further includes:

[0029] In the frequency sweep range, when the leaf frequency f i The characteristic frequency f of the acoustic transmission of the pipeline system p If they do not overlap, the curve will not show an obvious peak at the corresponding frequency point, and there is no characteristic frequency of sound transmission in the pipeline system.

[0030] Compared with the prior art, the advantageous effect of the frequency sweeping method for measuring the characteristic frequency of sound transmission of a sea-going pipeline system provided by the embodiment of the present invention is that, in view of the problem that the characteristic frequency of sound transmission of an actual complex sea-going pipeline system is difficult to calculate accurately, the frequency sweeping method can realize the characteristic frequency of sound transmission of the pipeline system through the speed regulation of the pump group, and can provide technical support for the control of blade frequency line spectrum noise of the sea-going pipeline system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A schematic diagram of a sweep frequency curve of a blade frequency sound source of a sea-going system pump group in a sweep frequency method for measuring a characteristic frequency of sound transmission in a sea-going pipeline system provided in an embodiment of the present invention;

[0032] Figure 2 A schematic diagram of a determination curve of the acoustic transmission characteristic frequency of a sea-access pipeline system in a sweep frequency method for measuring the acoustic transmission characteristic frequency of a sea-access pipeline system provided in an embodiment of the present invention;

[0033] Figure 3 The sweep frequency method for measuring the acoustic transmission characteristic frequency of a sea-access pipeline system provided in an embodiment of the present invention is a schematic diagram of a sweep frequency test for determining the acoustic transmission characteristic frequency of a sea-access pipeline system. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0035] Various aspects and features of the present application are described herein with reference to the accompanying drawings.

[0036] These and other characteristics of the present application will become apparent from the following description of a preferred form of embodiment given as a non-limiting example with reference to the accompanying drawings.

[0037] It should also be understood that, although the present application has been described with reference to some specific examples, those skilled in the art will be able to realize many other equivalent forms of the present application that have the features described in the claims and are therefore within the scope of protection defined thereby.

[0038] The above and other aspects, features and advantages of the present application will become more apparent in view of the following detailed description when taken in conjunction with the accompanying drawings.

[0039] Specific embodiments of the present application are described hereinafter with reference to the accompanying drawings; however, it should be understood that the embodiments applied for are merely examples of the present application, which may be implemented in a variety of ways. Well-known and / or repeated functions and structures are not described in detail to determine the true intent based on the user's historical operations and to avoid unnecessary or redundant details that make the present application unclear. Therefore, the specific structural and functional details applied for herein are not intended to be limiting, but are merely used as the basis and representative basis for the claims to teach those skilled in the art to use the present application in a variety of ways with substantially any suitable detailed structure.

[0040] This specification may use the phrases "in one embodiment," "in another embodiment," "in yet another embodiment," or "in other embodiments," all of which may refer to one or more of the same or different embodiments according to the present application.

[0041] The embodiment of the present invention provides a frequency sweeping method for measuring the characteristic frequency of acoustic transmission of a sea pipeline system, such as Figures 1 to 3 As shown, the method includes:

[0042] Based on the variable frequency control of the pump group, the frequency sweep of the Tonghai system is completed with the pump group as the blade frequency sound source to obtain the blade frequency;

[0043] In this embodiment, the frequency sweep of the Tonghai system is completed based on the variable frequency control of the pump group and the pump group is used as the blade frequency sound source, including:

[0044] Step 1: Control the pump unit variable frequency starter of the Tonghai system that is fully installed and can operate normally to start the Tonghai pump unit to the rated operating condition, reduce the pump unit to the lowest speed operating condition within the common operating range of the Tonghai system and operate stably, and record the flow rate Q0 and speed n0 of the pump unit under this operating condition;

[0045] According to the minimum adjustable frequency interval Δf of the frequency converter output frequency min , so that the output frequency increases by Δf min , control the pump group to increase the speed and run stably, ensure the acoustic state of the pump group is stable, and record the flow rate Q1 and speed n1 of the pump group under the current working condition;

[0046] Repeat the above process to continuously control the pump group to gradually increase the speed from the lowest speed condition to the highest speed condition n N, traverse the common operating range of the Tonghai system, and obtain a series of pump group flow rates Q i , speed n i , where i is any integer from 0 to N. So far, the frequency sweep of the Tonghai system is completed with the pump group as the blade frequency sound source. The schematic diagram of the frequency sweep curve can be found in the attached Figure 1 .

[0047] Step 2: Conduct an indirect test on the acoustic transmission response level of the pipeline system to obtain the vibration acceleration level of the pipeline interface flange monitoring point;

[0048] In this embodiment, the indirect test of the acoustic transmission response level of the pipeline system includes:

[0049] Within the common operating range of the Tonghai system, for each frequency sweep operating speed n i , keep the pump group running for the set time, after the acoustic state of the seawater pump is stable, use a single vibration sensor to monitor the vibration of the interface flange structure between the pump group and the pipeline, and record the blade frequency point f i =n i B / 60 vibration acceleration level Where i is any integer from 0 to N, B is the number of blades;

[0050] The vibration acceleration level indirectly reflects the acoustic response level caused by the pump blade frequency flow noise inside the pipeline system.

[0051] Step 3: Based on the common operating range of the Tonghai system, determine the characteristic frequency of the sound transmission of the pipeline system according to the blade frequency obtained by the sweep frequency test and the vibration acceleration level of the flange monitoring point of the pump and pipeline interface.

[0052] In this embodiment, based on the common operating range of the Tonghai system, the blade frequency obtained by the sweep frequency test and the vibration acceleration level of the flange monitoring point of the pump and pipeline interface are used to determine the acoustic transmission characteristic frequency of the pipeline system, including:

[0053] Corresponding to the common operating range of the Tonghai system, the pump group blade frequency-flange vibration monitoring point vibration level curve is drawn based on the blade frequency obtained by the sweep frequency test and the vibration acceleration level of the flange monitoring point of the pump and pipeline interface.

[0054] Furthermore, in the process of determining the characteristic frequency of acoustic transmission of the pipeline system based on the blade frequency obtained by the sweep frequency test and the vibration acceleration level of the monitoring point of the flange of the pump and pipeline interface, as the speed of the pump unit increases, the blade frequency vibration level of the pump unit flange increases with the speed. For details, see Figure 2 shown.

[0055] In this embodiment, within the frequency sweep range, when the blade frequency f i The characteristic frequency f of the acoustic transmission of the pipeline system pcoincidence, i.e., f i =f p When the frequency is 0, the curve shows an obvious peak at this frequency point, which proves that the pipeline system has a characteristic frequency of sound transmission within the frequency range of the sweep frequency, and the characteristic frequency is numerically equal to the peak frequency; otherwise, within the sweep frequency range, the pipeline system does not have a characteristic frequency of sound transmission.

[0056] It can be seen from the above technical scheme that the frequency sweeping method for measuring the characteristic frequency of sound transmission of the sea-going pipeline system provided in the above embodiment of the present invention can solve the problem that the characteristic frequency of sound transmission of the actual complex sea-going system is difficult to calculate accurately. It can realize the frequency sweeping test of the characteristic frequency of sound transmission of the pipeline system through the speed regulation of the pump group, and can provide technical support for the blade frequency line spectrum noise control of the sea-going system.

[0057] In order to understand the above technical solution more clearly and in detail, the following is a detailed description with reference to specific examples, as follows:

[0058] Taking a lake test bench of a Tonghai system with a rated flow rate of 100t / h as an example, a sweep frequency test was conducted on the acoustic transmission characteristic frequency of the pipeline system to solve the acoustic transmission problem of the Tonghai system inlet pipeline. The specific steps are as follows:

[0059] Step 1: Use the frequency converter to control the pump speed to the minimum. After the operation is stable, continuously adjust the pump speed to the maximum speed according to the minimum controllable frequency interval of the frequency converter (about 2Hz), so as to realize the acoustic frequency sweep of the pump blade frequency on the inlet pipeline;

[0060] Step 2: Each time the inverter speed is increased, the pump speed is measured synchronously, converted into blade frequency, the radial vibration level of the pump inlet flange and the sound pressure level of the radiated noise at the port are measured, and the blade frequency-vibration level / radiated noise curve is drawn;

[0061] Step 3: Determine the peak value of the blade frequency-vibration level curve in the frequency range corresponding to the common operating range of the Tonghai system. The frequency corresponding to the peak value is 83Hz, which is the characteristic frequency of the inlet pipe sound transmission.

[0062] In summary, it can be seen that the blade frequency line spectrum radiation noise of the Tonghaikou system is mainly generated by the sound transmission mode of the pipeline fluid medium. When the blade frequency line spectrum frequency of the pump group coincides with the characteristic frequency of the sound transmission of the pipeline system, the radiation noise of the Tonghaikou also peaks synchronously, which is 6dB to 18dB higher than the radiation noise of the adjacent higher flow condition, and is close to the pipe mouth radiation noise of the rated condition.

[0063] The above embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present invention.

Claims

1. A frequency sweeping method for measuring the characteristic frequency of acoustic transmission of a sea-going pipeline system, characterized in that: include: Based on the variable frequency control of the pump group, the frequency sweep of the Tonghai system is completed with the pump group as the blade frequency sound source to obtain the blade frequency; Conduct indirect test on the acoustic transmission response level of the pipeline system to obtain the vibration acceleration level of the pipeline interface flange monitoring point; Based on the common operating range of the Tonghai system, the characteristic frequency of acoustic transmission of the pipeline system is determined according to the blade frequency obtained by the sweep frequency test and the vibration acceleration level of the flange monitoring point of the pump and pipeline interface.

2. The frequency sweeping method for measuring the acoustic transmission characteristic frequency of the sea pipeline system according to claim 1 is characterized in that: The method of completing the frequency sweep of the Tonghai system based on the variable frequency control of the pump group and taking the pump group as the blade frequency sound source includes: Control the pump unit variable frequency starter of the Tonghai system that is fully installed and can operate normally to start the Tonghai pump unit to the rated operating condition, reduce the pump unit to the lowest speed condition within the common operating range of the Tonghai system and operate stably, and record the flow rate Q0 and speed n0 of the pump unit under this condition; According to the minimum adjustable frequency interval Δf of the frequency converter output frequency min , so that the output frequency increases by Δf min , control the pump group to increase the speed and run stably, ensure the acoustic state of the pump group is stable, and record the flow rate Q1 and speed n1 of the pump group under the current working condition; Repeat the above process to continuously control the pump group to gradually increase the speed from the lowest speed condition to the highest speed condition n N , traverse the common operating range of the Tonghai system, and obtain a series of pump group flow rates Q i , speed n i , where i is any integer from 0 to N. So far, the frequency sweep of the Tonghai system is completed with the pump group as the blade frequency sound source.

3. The frequency sweeping method for measuring the acoustic transmission characteristic frequency of the sea pipeline system according to claim 2 is characterized in that: The indirect test of the acoustic transmission response level of the pipeline system includes: Within the common operating range of the Tonghai system, for each frequency sweep operating speed n i , keep the pump group running for the set time, after the acoustic state of the seawater pump is stable, use a single vibration sensor to monitor the vibration of the interface flange structure between the pump group and the pipeline, and record the blade frequency point f i =n i B / 60 vibration acceleration level Where i is any integer from 0 to N, B is the number of blades; The vibration acceleration level indirectly reflects the acoustic response level caused by the pump blade frequency flow noise inside the pipeline system.

4. The frequency sweeping method for measuring the acoustic transmission characteristic frequency of the sea pipeline system according to claim 3 is characterized in that: The method of determining the acoustic transmission characteristic frequency of the pipeline system based on the common operating range of the Tonghai system and the blade frequency obtained by the sweep frequency test and the vibration acceleration level of the flange monitoring point of the pump and pipeline interface includes: Corresponding to the common operating range of the Tonghai system, the pump group blade frequency-flange vibration monitoring point vibration level curve is drawn based on the blade frequency obtained by the sweep frequency test and the vibration acceleration level of the flange monitoring point of the pump and pipeline interface.

5. The frequency sweeping method for measuring the acoustic transmission characteristic frequency of the sea pipeline system according to claim 4 is characterized in that: In the process of determining the characteristic frequency of acoustic transmission of the pipeline system based on the blade frequency obtained by the sweep frequency test and the vibration acceleration level of the monitoring point of the flange of the pump and pipeline interface, As the speed of the pump unit increases, the blade frequency vibration level of the pump unit flange tends to increase with the increase of speed.

6. The frequency sweeping method for measuring the acoustic transmission characteristic frequency of the sea pipeline system according to claim 5, characterized in that: In the process of determining the acoustic transmission characteristic frequency of the pipeline system according to the blade frequency obtained by the frequency sweep test and the vibration acceleration level of the monitoring point of the flange of the pump and pipeline interface, the frequency sweep method further includes: In the frequency sweep range, when the leaf frequency f i The characteristic frequency f of the acoustic transmission of the pipeline system p coincidence, that is, f i =f p When , the curve shows an obvious peak at this frequency point, proving that the pipeline system has a characteristic frequency of sound transmission within the frequency range of the sweep, and the characteristic frequency is numerically equal to the peak frequency.

7. The frequency sweeping method for measuring the acoustic transmission characteristic frequency of the sea pipeline system according to claim 6 is characterized in that: In the process of determining the acoustic transmission characteristic frequency of the pipeline system according to the blade frequency obtained by the frequency sweep test and the vibration acceleration level of the monitoring point of the flange of the pump and pipeline interface, the frequency sweep method further includes: In the frequency sweep range, when the leaf frequency f i The characteristic frequency f of the acoustic transmission of the pipeline system p If they do not overlap, the curve will not show an obvious peak at the corresponding frequency point, and there is no characteristic frequency of sound transmission in the pipeline system.

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