Centrifugal pump blade frequency line spectral flow noise source modeling method

Abstract

The embodiment of the invention provides a centrifugal pump blade frequency line spectral flow noise source modeling method through a mode of spatially distributing dipole clusters, and the method comprises the steps that moving blades are three-dimensionally split into independent three-dimensional models from a pump set impeller, and the moving blades comprise a plurality of main blades and a plurality of splitter blades; along the chord length direction of the moving blade, the moving blade overflowing surface is segmented into a plurality of segments; dipole acoustic equivalent processing is conducted on each segment in the multiple segments of the moving blade, and an equivalent sound source is obtained; and establishing a pump set-pipeline sound field finite element model by adopting the obtained equivalent sound source, and performing simulation calculation on the pump set inlet pipeline flow noise. Compared with an existing engineering estimation method, the method is higher in calculation precision, and meanwhile, the problem that a sound field grid of a surface sound source method depends on three-dimensional geometric modeling of the impeller is avoided. And a technical support is provided for flow noise performance evaluation of a pump set of a Kingston system and control effect analysis of a system flow noise control scheme.

Description

Technical Field

[0001] The invention relates to the technical field of ship machinery noise control, in particular to a method for modeling a sound source of frequency line spectrum flow noise of a centrifugal pump blade. Background Art

[0002] Underwater noise performance is a key performance that affects the development and application of high-performance ships in my country. One of the main noise sources of high-performance ships is the centrifugal pump group of the large-flow sea-going system. The periodic pulsating hydrodynamic force generated by the high-speed rotation of the pump group impeller produces a high level of blade frequency line spectrum noise, which has an important impact on the underwater noise of the ship and is the focus of noise control of the ship's sea-going system.

[0003] In the actual ship engineering, in order to control the flow noise of the sea-going system, two measures are usually adopted: one is to develop a low-noise seawater pump to reduce the blade frequency flow noise level at the source; the other is to install a muffler on the pipeline to control the system noise on the transmission path. Whether it is the development of a low-noise seawater pump or a muffler-based sea-going system pipeline flow noise transmission control scheme, it is necessary to carry out a fast and relatively accurate calculation of the seawater pump blade frequency flow noise level, so as to optimize the flow noise performance of various pump group design schemes, and provide an effective pump group blade frequency sound source for the analysis of the sea-going system flow noise control effect, thereby ensuring the best control effect of the underwater noise of the sea-going estuary.

[0004] At present, there are two methods for calculating pump group flow noise:

[0005] (1) Engineering estimation method based on flow rate and head

[0006] This method uses the flow rate and head parameters of the pump group to estimate the fluid power of the pump group. Based on experience, the acoustic energy of the flow noise is estimated at a certain ratio, and then the total sound pressure level and octave data of the flow noise in a certain frequency band are given. The blade frequency line spectrum noise energy of the Tonghai system flow noise accounts for up to 50%. The project needs to carry out a single frequency pipeline sound transfer analysis for the blade frequency. Therefore, this estimation method cannot meet the needs of blade frequency flow noise analysis and evaluation in the project.

[0007] (2) Blade surface sound source method based on acoustic analogy theory

[0008] The blade surface sound source method requires accurate division of the internal sound field grid of the pump group according to the three-dimensional geometry of the impeller, and is heavily dependent on the pump group blade shaping scheme. As the flow surface of the pump group itself is optimized and changed, the flow field grid inside the pump group needs to be re-divided, which increases the workload of the pump group acoustic performance evaluation and cannot adapt to the rapid iterative design of multiple pump group schemes. Summary of the invention

[0009] In view of the above-mentioned problems existing in the prior art, and based on engineering practice, it is known that the blade frequency of a low-noise Tonghai pump group is usually lower than 300Hz. In theory, the radiation sound field of the low-frequency (not higher than 315Hz) hydrodynamic force (surface force) is basically equivalent to the radiation sound field of the concentrated force. An embodiment of the present invention provides a centrifugal pump blade frequency line spectrum flow noise source modeling method. By segmenting the moving blades, an acoustic equivalent spatially distributed dipole cluster is established. When the sound field grid inside the pump group remains unchanged, the multiple schemes of the three-dimensional modeling of the moving blades of the pump group are quickly adapted to the rapid iteration by changing the dipole coordinates. While retaining the high accuracy advantage of the surface sound source method, the problem of repeated reconstruction of the sound field grid inside the pump group is avoided.

[0010] The embodiment of the present invention provides a method for modeling the sound source of centrifugal pump blade line spectrum flow noise, comprising:

[0011] The moving blades of the pump group impeller are three-dimensionally split into independent three-dimensional models, wherein the moving blades include a plurality of main blades and a plurality of splitter blades;

[0012] The flow surface of the moving blade is divided into a plurality of sections along the chord length direction of the moving blade;

[0013] Performing dipole acoustic equivalent processing on each of the multiple segments of the moving blade to obtain an equivalent sound source;

[0014] The obtained equivalent sound source is used to establish the finite element model of the pump group-pipeline sound field, and the pump group inlet pipeline flow noise is simulated and calculated.

[0015] In some embodiments of the present invention, the flow surface of the moving blade is divided into a plurality of segments along the chord length direction of the moving blade, including:

[0016] The flow surface of the centrifugal pump moving blade is divided into several segments along the blade chord length direction. For each single segment, the hydrodynamic pressure of the flow surface is integrated to calculate the hydrodynamic vector resultant of the segment. The calculation formula is as follows:

[0017]

[0018] Where: p represents the hydrodynamic pressure of the segmented flow surface; represents the vector area of ​​the flow surface of the i-th segment; represents the hydrodynamic vector resultant force of the ith segment.

[0019] In some embodiments of the present invention, performing dipole acoustic equivalent processing on each of the multiple segments of the moving blade to obtain an equivalent sound source includes:

[0020] Calculate the three-dimensional high-precision flow field distribution of the impeller, extract the fluid pressure of each segment, integrate and calculate the hydrodynamic vector force, and determine the intensity and direction of the dipole sound source;

[0021] A dipole is set at the center of each segment set to form a spatially distributed dipole cluster with a corresponding number of segments, which serves as the equivalent sound source of the frequency line spectrum flow noise of the pump group blades.

[0022] In some embodiments of the present invention, the dipole acoustic equivalent processing is performed on each of the multiple segments of the moving blade to obtain an equivalent sound source, specifically:

[0023] For each single segment, the spatial position of the dipole is located by the geometric center of the segment, the dipole sound source intensity is determined by the magnitude of the segment hydrodynamic vector resultant force, and the direction of the dipole is located by the direction of the segment hydrodynamic vector resultant force. A single dipole is used to replace the blade segment acoustically. The equivalent dipole sound source calculation formula is as follows:

[0024]

[0025] Where: The spatial coordinates representing the geometric center of the blade segment; Represents the unit source intensity dipole; F l The lift component of the resultant force of the segmented hydrodynamic vector; F d The drag component representing the resultant force of the segmented hydrodynamic vector; represents the speed vector; represents the distance vector between the dipole coordinates and the origin; Represents the harmonic parameters related to the rotation angular frequency.

[0026] In some embodiments of the present invention, the equivalent sound source is used to establish a pump group-pipeline sound field finite element model, and the pump group inlet pipeline flow noise is simulated and calculated, including:

[0027] The equivalent sound source was used in combination with finite element analysis tools to establish a finite element model of the pump-pipeline sound field, and the sound pressure level of the pump inlet pipeline flow noise was simulated and calculated.

[0028] In some embodiments of the present invention, the method further comprises:

[0029] The simulation results are compared with the experimental test results. If the deviation is not greater than the set value, it is determined that the engineering evaluation is met.

[0030] In some embodiments of the present invention, the set value is a decibel value not greater than 1.8 dB.

[0031] In some embodiments of the present invention, the moving blades specifically include 6 main blades and 6 splitter blades, and when segmenting, each main blade is divided into 6 sections, and each splitter blade is divided into 3 sections, for a total of 54 sections.

[0032] Compared with the prior art, the beneficial effect of the centrifugal pump blade line spectrum flow noise sound source modeling method provided by the embodiment of the present invention is that it provides a sound source modeling method for calculating the centrifugal pump blade line spectrum flow noise by means of spatially distributed dipole clusters, which has higher calculation accuracy than the current engineering estimation method, and at the same time avoids the problem that the sound field grid of the surface sound source method depends on the three-dimensional geometric modeling of the impeller. The present invention can provide technical support for the evaluation of the flow noise performance of the Tonghai system pump group and the control effect analysis of the system flow noise control scheme. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of a centrifugal pump moving blade segmentation according to a centrifugal pump blade line spectrum flow noise sound source modeling method provided by an embodiment of the present invention;

[0034] Figure 2 Schematic diagram of the equivalent centrifugal pump blade sound source of the spatially distributed dipole cluster provided in the centrifugal pump blade line spectrum flow noise sound source modeling method provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] 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.

[0036] Various aspects and features of the present application are described herein with reference to the accompanying drawings.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] The embodiment of the present invention provides a method for modeling the sound source of centrifugal pump blade frequency spectrum flow noise. Figure 1 and Figure 2 As shown, the method includes:

[0043] The moving blades of the pump group impeller are three-dimensionally split into independent three-dimensional models, wherein the moving blades include a plurality of main blades and a plurality of splitter blades;

[0044] The flow surface of the moving blade is divided into a plurality of sections along the chord length direction of the moving blade;

[0045] In this embodiment, the flow surface of the moving blade is divided into a plurality of segments along the chord length direction of the moving blade, including:

[0046] The flow surface of the centrifugal pump moving blade is divided into several segments along the blade chord length direction. For each single segment, the hydrodynamic pressure of the flow surface is integrated to calculate the hydrodynamic vector resultant of the segment. The calculation formula is as follows:

[0047]

[0048] Where: p represents the hydrodynamic pressure of the segmented flow surface; represents the vector area of ​​the flow surface of the i-th segment; represents the hydrodynamic vector resultant force of the ith segment.

[0049] Performing dipole acoustic equivalent processing on each of the multiple segments of the moving blade to obtain an equivalent sound source;

[0050] In some embodiments of the present invention, performing dipole acoustic equivalent processing on each of the multiple segments of the moving blade to obtain an equivalent sound source includes:

[0051] Calculate the three-dimensional high-precision flow field distribution of the impeller, extract the fluid pressure of each segment, integrate and calculate the hydrodynamic vector force, and determine the intensity and direction of the dipole sound source;

[0052] A dipole is set at the center of each segment set to form a spatially distributed dipole cluster with a corresponding number of segments, which serves as the equivalent sound source of the frequency line spectrum flow noise of the pump group blades.

[0053] Specifically, in this embodiment, the dipole acoustic equivalent processing is performed on each of the multiple segments of the moving blade to obtain an equivalent sound source, specifically:

[0054] For each single segment, the spatial position of the dipole is located by the geometric center of the segment, the dipole sound source intensity is determined by the magnitude of the segment hydrodynamic vector resultant force, and the direction of the dipole is located by the direction of the segment hydrodynamic vector resultant force. A single dipole is used to replace the blade segment acoustically. The equivalent dipole sound source calculation formula is as follows:

[0055]

[0056] Where: The spatial coordinates representing the geometric center of the blade segment; Represents the unit source intensity dipole; F l The lift component of the resultant force of the segmented hydrodynamic vector; F d The drag component representing the resultant force of the segmented hydrodynamic vector; represents the speed vector; represents the distance vector between the dipole coordinates and the origin; Represents the harmonic parameters related to the rotation angular frequency.

[0057] The equivalent sound source is used to establish the pump group-pipeline acoustic field finite element model, and the pump group inlet pipeline flow noise is simulated and calculated, including:

[0058] The equivalent sound source was used in combination with finite element analysis tools to establish a finite element model of the pump-pipeline sound field, and the sound pressure level of the pump inlet pipeline flow noise was simulated and calculated.

[0059] Furthermore, the method further includes: comparing the simulation calculation result with the test result, and if the deviation is not greater than a set value, determining that the engineering assessment is satisfied. As an example, the set value may be a decibel value not greater than 1.8 dB.

[0060] In order to facilitate the understanding of the above technical solution, the specific implementation of the present invention is described below by taking the model Tonghai pump group as an example, as follows:

[0061] Step 1: First, split the moving blades from the pump unit impeller into independent 3D models. The moving blades consist of 6 main blades and 6 splitter blades. See the attached Figure 2 shown.

[0062] Step 2: Segment the moving blades along the chord length direction, for example: divide each main blade into 6 segments, each splitter blade into 3 segments, a total of 54 segments, see the attached Figure 2 shown.

[0063] Step 3: Use commercial CFD software to calculate the three-dimensional high-precision flow field distribution of the impeller, extract the fluid pressure of each segment, integrate and calculate the hydrodynamic vector force, determine the intensity and direction of the dipole sound source, set a dipole at the center of each segment set, and form 54 spatially distributed dipole clusters as the equivalent sound source of the pump group blade frequency line spectrum flow noise. See the attached Figure 2 shown.

[0064] Step 4: Using this sound source and commercial acoustic finite element software, a pump-pipeline sound field finite element model is established to simulate the sound pressure level of the pump group inlet pipeline flow noise. The deviation between the result and the experimental test result is no more than 1.8dB, which meets the accuracy requirements of the engineering assessment. See the table below for details.

[0065] Serial number Working conditions description The present invention Test value deviation 1 980r / min, flow rate 300t / h, blade frequency 98Hz 159.1dB 158.9dB 0.2dB 2 686r / min, flow rate 210t / h, blade frequency 68.6Hz 162.5dB 160.7dB 1.8dB

[0066] It can be seen from the above technical solution that the above embodiment of the present invention provides a centrifugal pump blade frequency line spectrum flow noise sound source modeling method by means of spatially distributed dipole clusters, which has higher calculation accuracy than the current engineering estimation method, and avoids the problem that the sound field grid of the surface sound source method depends on the three-dimensional geometric modeling of the impeller. The present invention can provide technical support for the evaluation of the flow noise performance of the Tonghai system pump group and the control effect analysis of the system flow noise control scheme.

[0067] 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 method for modeling the sound source of centrifugal pump blade line spectrum flow noise, characterized in that: include: The moving blades of the pump group impeller are three-dimensionally split into independent three-dimensional models, wherein the moving blades include a plurality of main blades and a plurality of splitter blades; The flow surface of the moving blade is divided into a plurality of sections along the chord length direction of the moving blade; Performing dipole acoustic equivalent processing on each of the multiple segments of the moving blade to obtain an equivalent sound source; The obtained equivalent sound source is used to establish the finite element model of the pump group-pipeline sound field, and the pump group inlet pipeline flow noise is simulated and calculated.

2. The centrifugal pump blade line spectrum flow noise source modeling method according to claim 1 is characterized in that: The flow surface of the moving blade is divided into a plurality of sections along the chord length direction of the moving blade, including: The flow surface of the centrifugal pump moving blade is divided into several segments along the blade chord length direction. For each single segment, the hydrodynamic pressure of the flow surface is integrated to calculate the hydrodynamic vector resultant of the segment. The calculation formula is as follows: Where: p represents the hydrodynamic pressure of the segmented flow surface; represents the vector area of ​​the flow surface of the i-th segment; represents the hydrodynamic vector resultant force of the ith segment.

3. The method for modeling the sound source of centrifugal pump blade line spectrum flow noise according to claim 2 is characterized in that: The step of performing dipole acoustic equivalent processing on each of the multiple segments of the moving blade to obtain an equivalent sound source includes: Calculate the three-dimensional high-precision flow field distribution of the impeller, extract the fluid pressure of each segment, integrate and calculate the hydrodynamic vector force, and determine the intensity and direction of the dipole sound source; A dipole is set at the center of each segment set to form a spatially distributed dipole cluster with a corresponding number of segments, which serves as the equivalent sound source of the frequency line spectrum flow noise of the pump group blades.

4. The method for modeling the sound source of centrifugal pump blade line spectrum flow noise according to claim 2 is characterized in that: The dipole acoustic equivalent processing is performed on each of the multiple segments of the moving blade to obtain an equivalent sound source, specifically: For each single segment, the spatial position of the dipole is located by the geometric center of the segment, the dipole sound source intensity is determined by the magnitude of the segment hydrodynamic vector resultant force, and the direction of the dipole is located by the direction of the segment hydrodynamic vector resultant force. A single dipole is used to replace the blade segment acoustically. The equivalent dipole sound source calculation formula is as follows: Where: The spatial coordinates representing the geometric center of the blade segment; Represents the unit source intensity dipole; F l The lift component of the resultant force of the segmented hydrodynamic vector; F d The drag component representing the resultant force of the segmented hydrodynamic vector; represents the speed vector; represents the distance vector between the dipole coordinates and the origin; Represents the harmonic parameters related to the rotation angular frequency.

5. The method for modeling the sound source of centrifugal pump blade line spectrum flow noise according to claim 4 is characterized in that: The equivalent sound source is used to establish a pump group-pipeline sound field finite element model, and the pump group inlet pipeline flow noise is simulated and calculated, including: The equivalent sound source was used in combination with finite element analysis tools to establish a finite element model of the pump-pipeline sound field, and the sound pressure level of the pump inlet pipeline flow noise was simulated and calculated.

6. The centrifugal pump blade line spectrum flow noise source modeling method according to claim 5 is characterized in that: The method further comprises: The simulation results are compared with the experimental test results. If the deviation is not greater than the set value, it is determined that the engineering evaluation is met.

7. The method for modeling the sound source of centrifugal pump blade line spectrum flow noise according to claim 6, characterized in that: The set value is a decibel value not greater than 1.8 dB.

8. The method for modeling the sound source of centrifugal pump blade line spectrum flow noise according to claim 7, characterized in that: The moving blades specifically include 6 main blades and 6 splitter blades, and when segmented, each main blade is divided into 6 sections, and each splitter blade is divided into 3 sections, for a total of 54 sections.

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