A method for estimating the sound power spectrum of a marine fan and a method for predicting the noise inside a ship's cabin

Abstract

The present application provides a method for estimating the sound power spectrum of a marine fan and a method for predicting the noise in a cabin, including: obtaining the flow rate Q and pressure T from the original parameters of the fan p ; based on formula (1): L wf‑exp = 10lgQ + 20lgT p + 10 + C wf , obtain the sound power level L wf‑exp at each octave band of the fan; where: C wf is the octave band correction value of the air noise of the fan; substitute the sound power levels L wf‑exp at each octave band of the fan into formula (2)#imgabs0# to calculate the empirical value L w‑exp of the total sound power level of the fan; check whether the rated value L w‑man of the total sound power level is included in the original parameters of the fan; if not, use the sound power levels L wf‑exp at each octave band of the fan as the sound power spectrum L wf of the fan; if so, substitute the sound power levels L wf‑exp at each octave band of the fan, the empirical value L w‑exp of the total sound power level, and the rated value L w‑man of the total sound power level into formula (3): L wf = L wf‑exp - (L w‑exp - L w‑man ), and calculate the actual sound power spectrum L wf of the fan.

Description

Technical Field

[0001] This application relates to the technical field of ship noise, and more specifically, to a method for estimating the sound power spectrum of a marine fan and a method for predicting the noise in a ship cabin. Background Art

[0002] With the continuous development of the shipbuilding industry, on the premise that the ship's safety and speed meet the requirements, the issue of how to improve the comfort of the living and working environment on board has received wide attention. Cabin noise is an important factor affecting the living and working environment, and the fan in the cabin is the main noise source equipment. Therefore, how to quickly and accurately evaluate the noise of the fan in the cabin at the initial stage of ship design has become an important topic.

[0003] The sound power level is an important parameter for evaluating the noise level. At present, the acquisition of the sound power level spectrum of the fan is usually estimated by empirical formulas or tested by bench tests. Among them, the bench test needs to be carried out according to the standard and in a specified environment, and this method is often costly and difficult to obtain in the initial design stage. Compared with the bench test method, the method of estimating by empirical formula is more widely used. However, due to the continuous improvement of the fan process and the conservative estimation of the empirical formula, the sound power spectrum estimated by the empirical formula alone is often larger than the sound power spectrum under the actual working conditions, which greatly affects the accuracy of the cabin noise level evaluation. Summary of the Invention

[0004] The purpose of the embodiments of this application is to provide a method for estimating the sound power spectrum of a marine fan, which can correct the sound power spectrum calculated by the empirical formula according to the rated value of the total sound power level in the original parameters of the fan, so as to estimate a sound power spectrum closer to the actual sound power spectrum of the fan.

[0005] Another purpose of the embodiments of this application is also to provide a method for predicting the noise in a ship cabin using the above method for estimating the sound power spectrum of a marine fan.

[0006] In the first aspect, a method for estimating the sound power spectrum of a marine fan is provided, including:

[0007] Obtain the flow rate Q and pressure T from the original parameters of the fan p ;

[0008] Based on formula (1): L wf-exp = 10lgQ + 20lgT p + 10 + C wf , obtain the sound power level L wf-exp of each octave band of the fan; where: C wf is the octave band correction value of the air noise of the fan;

[0009] Substitute the sound power level L wf-exp of each octave band of the fan into formula (2) Calculate the empirical value L of the total sound power level of the fan w-exp ; w 0 is the reference sound power, with a value of 10 -12 ;

[0010] Search in the original parameters of the fan to see if it contains the rated value L of the total sound power level w-man ;

[0011] If it does not contain, then use the sound power level L at each octave band of the fan wf-exp as the sound power spectrum L of the fan wf ;

[0012] If it contains, then input the sound power level L at each octave band of the fan wf-exp , the empirical value L of the total sound power level w-exp and the rated value L of the total sound power level into formula (3): L w-man = L wf -(L wf-exp - L w-exp - L w-man ), and calculate the actual sound power spectrum L of the fan wf .

[0013] In one embodiment, when the rated value L of the total sound power level is not included in the original parameters of the fan w-man it further includes:

[0014] Judge whether the original parameters of the fan contain the rated value L of the total sound pressure level P-man ;

[0015] Calculate the rated value L of the total sound power level according to the conversion formula between the total sound pressure level and the total sound power level w-man :

[0016]

[0017] Where: S: the area of the measurement surface;

[0018] S O : 1m 2 .

[0019] In one embodiment, the acquisition of the C wf includes:

[0020] Obtain the type of the fan from the original parameters of the fan;

[0021] Determine the value of the C wf according to the type of the fan.

[0022] In one embodiment, the types of the fan include centrifugal fans and axial fans.

[0023] Second aspect, the present application also provides a method for predicting the noise inside a cabin, including:

[0024] Obtain the fan data arranged at different positions inside the cabin;

[0025] Obtain the fan parameters from the fan data;

[0026] Judge whether each fan parameter contains a sound power spectrum;

[0027] If so, obtain the sound power spectrum of the fan;

[0028] If not, obtain the sound power spectrum according to the sound power spectrum estimation method of the marine fan described in any one of the embodiments in the first aspect;

[0029] Substitute the sound power spectrum of each fan into the cabin noise prediction model to predict the noise inside the cabin.

[0030] In one embodiment, before the fan original parameters do not contain a sound power spectrum and before the sound power spectrum estimation method of the marine fan described in any one of the embodiments in the first aspect, it further includes:

[0031] Search for fans of the same model in the vibration noise database;

[0032] Judge whether the original parameters of the fans of the same model contain a sound power spectrum.

[0033] In one embodiment, the substituting the sound power spectrum of each fan into the cabin noise prediction model to predict the noise inside the cabin includes:

[0034] Establish a three-dimensional model of the cabin where the noise is to be predicted;

[0035] Input the sound power spectrum of each fan into the model parameters to predict the noise inside the cabin.

[0036] In one embodiment, the obtaining the fan data arranged at different positions inside the cabin includes:

[0037] Determine the ventilation form according to the ventilation requirements at different positions inside the cabin;

[0038] Select the fan model and the number of fans based on different ventilation forms;

[0039] Obtain the fan data of each model.

[0040] The beneficial effects of the sound power spectrum estimation method of the marine fan and the cabin noise prediction method in the present application are:

[0041] 1. This application uses the total sound power level in the original parameters of the fan to correct the sound power spectrum. Compared with the traditional method of calculating the sound power spectrum using a single empirical formula, the sound power spectrum estimated by this method is consistent with the actual sound power spectrum, which is beneficial to the noise level assessment in the cabin during the initial design stage.

[0042] 2. By quickly and accurately obtaining the sound power spectrum of each fan in the preliminary design stage, the noise level in the cabin can be predicted based on the sound power spectrum of each fan, ensuring that the cabin noise assessment meets the requirements of ship design and construction. Brief Description of the Drawings

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0044] Figure 1 It is a flowchart of a method for predicting cabin noise according to an embodiment of the present application. Detailed Embodiments

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Generally, the components of the embodiments of the present application described and illustrated in the drawings here can be arranged and designed in various different configurations.

[0046] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the present application claimed, but merely represents the selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application.

[0047] With the development of the shipbuilding industry and the promulgation and implementation of IMO MSC337(91), the requirements for noise control in ship cabins are becoming increasingly stringent. This requires that at the initial stage of ship design, the noise in the cabin can be predicted quickly and accurately. As an important sound source device in the cabin, the sound power spectrum of the fan during its operation is an important parameter for evaluating its noise. At present, the traditional method for obtaining the sound power spectrum of the fan is based on empirical formulas. However, with the improvement of fan technology and the conservative calculation of empirical formulas, the value of the fan sound power spectrum calculated by empirical formulas is usually much larger than the actual sound power spectrum, which seriously affects the accuracy of the initial evaluation of the noise level in the cabin and is not conducive to the accurate prediction of the noise in the cabin at the initial stage.

[0048] Based on the above background, the inventors of this application analyzed the differences in the initial parameters of the fan and adopted different methods to quickly and accurately obtain the sound power spectrum of the fan. At the initial stage of design, each fan parameter contains the sound power spectrum, and then the sound power spectra of each fan are superimposed to predict the noise of the entire cabin, thus realizing the quick and accurate prediction of the noise in the cabin.

[0049] In the first aspect, this application provides a method for estimating the sound power spectrum of a marine fan.

[0050] The method for estimating the sound power spectrum of the marine fan in this application includes:

[0051] Obtain the flow rate Q and pressure T from the original parameters of the fan p , based on formula (1): L wf-exp = 10lgQ + 20lgT p + 10 + C wf , obtain the sound power level L wf-exp at each octave of the fan, where C wf is the octave correction value of the fan air noise;

[0052] Substitute the sound power level L wf-exp at each octave of the fan into formula (2) w 0 = 10 -12 W (watts), and calculate the empirical value L w-exp of the total sound power level of the fan;

[0053] Check whether the original parameters of the fan contain the rated value L w-man of the total sound power level;

[0054] If not, take the sound power level L wf-exp at each octave of the fan as the sound power spectrum L wf of the fan;

[0055] If it contains, take the sound power level L wf-exp, the empirical value of the total sound power level L w-exp and the rated value of the total sound power level L w-man Substitute into formula (3): L wf = L wf-exp -(L w-exp - L w-man ), and calculate the actual sound power spectrum L wf .

[0056] In the above implementation method, based on the flow rate Q and pressure T in the original parameters of the fan p calculate the empirical value of the sound power spectrum L wf-exp , and combine it with the rated value of the total sound power level L of the fan in the original parameters of the fan w-man , correct the empirical value of the sound power spectrum L wf-exp , so as to estimate the actual sound power spectrum L wf that is basically consistent with the operating sound power spectrum of the fan. Compared with the prediction by a single empirical formula, the above method realizes the accurate prediction of the sound power spectrum of the fan, is more in line with the actual sound power spectrum of the fan, and is conducive to accurately predicting the fan noise and the noise level in the cabin at the initial stage of design.

[0057] In an implementation scheme, when the fan parameters do not include the rated value of the total sound power level, it is also possible to judge whether the fan parameters include the rated value of the total sound pressure level, and calculate the rated value of the total sound power level L w-man according to the conversion formula between the total sound pressure level and the total sound power level:

[0058]

[0059] S: the area of the measurement surface;

[0060] S O : 1m 2 .

[0061] In an implementation scheme, C wf is the octave correction value of the air noise of the fan obtained based on the fan type, that is, obtain the fan type in the original parameters of the fan, and the fan type includes centrifugal fans and axial fans. The specific value of C wf is shown in Table 1:

[0062] Table 1 Octave correction value C of the air noise of the fan wf

[0063] Frequency 63 125 250 500 1000 2000 4000 8000 Centrifugal fan dB 6 7 11 16 18 22 26 33 Axial flow fan dB 10 9 8 8 8 10 14 15

[0064] In this application, in order to verify the accuracy of the fan sound power spectrum calculated by the above ship fan sound power spectrum estimation method, the above method is actually applied to the prediction of the fan sound power spectrum. The specific implementation process is as follows:

[0065] Obtain the flow rate Q: 800 m 3 / h, pressure T p : 380 Pa, type: centrifugal duct fan, total sound power level: 55.2 dB.

[0066] From formula (1): L wf-exp = 10lgQ + 20lgT p + 10 + C wf , obtain the sound power level L on each octave band of the fan wf-exp As shown in Table 2, where C wf Take the value according to the centrifugal fan:

[0067] Table 2 Sound power levels on each octave band calculated by formula (1)

[0068] Frequency 63 125 250 500 1000 2000 4000 8000 Sound power dB 78.8 79.8 83.8 88.8 90.8 94.8 98.8 105.8

[0069] Input the sound power levels L on each octave band of the fan obtained from formula (1) wf-exp into formula (2): Where: w 0 = 10 -12 W (watts), the empirical value of the total sound power level of the fan calculated is L w-exp is 107.1 dB.

[0070] Find that the rated value of the total sound power level in the original parameters of the fan is 55.2 dB.

[0071] Take the rated value of the total sound power level L w-man = 55.2 dB, the empirical value of the total sound power level L w-exp = 107.1 dB, and the sound power levels L on each octave band of the fan obtained from formula (1) wf-exp as the input, based on formula (3): L wf = L wf-exp -(L w-exp - L w-man ), calculate the actual sound power spectrum L of the fan wf , as shown in Table 3:

[0072] Table 3 Actual sound power spectrum of the fan calculated

[0073] Frequency 63 125 250 500 1000 2000 4000 8000 Overall level Sound power dB 26.9 27.9 31.9 36.9 38.9 42.9 46.9 53.9 55.2

[0074] In summary, the calculation results show that when using a single empirical formula (1) to calculate the sound power spectrum of the fan, the estimated total sound power level of the fan is 107.1 dB, which is significantly too large; on the contrary, with the method in this application, the estimated total sound power level after correction is 55.2 dB, which is consistent with the actual total sound power level in the fan parameters, and at the same time, the corrected actual sound power spectrum is obtained.

[0075] In a second aspect, the present application provides a method for predicting the noise inside a cabin.

[0076] See Figure 1 , the method for predicting the noise inside the cabin in the present application includes the following steps:

[0077] Obtain the fan data arranged at different positions inside the cabin;

[0078] Obtain the fan parameters from the fan data, and the fan parameters include the manufacturer, model, flow rate, pressure, total sound power level, total sound pressure level, etc.;

[0079] Determine whether each fan parameter contains a sound power spectrum;

[0080] If so, obtain the sound power spectrum of the fan;

[0081] If not, obtain the sound power spectrum according to the sound power spectrum estimation method of the marine fan described in any one of the above-mentioned first aspects;

[0082] Substitute the sound power spectrum of each fan into the cabin noise prediction model to predict the noise inside the cabin.

[0083] In the above implementation method, by quickly and accurately obtaining the sound power spectrum of each fan in the early stage of design, the noise inside the cabin is evaluated based on the sound power spectra of all the fans inside the cabin.

[0084] In one implementation, before the sound power spectrum is not included in the above-mentioned original fan parameters and before the sound power spectrum estimation method of the marine fan described in any one of the first aspects, it further includes:

[0085] Search for fans of the same model in the vibration and noise database;

[0086] Judge whether the original parameters of the fans of the same model contain a sound power spectrum.

[0087] In one implementation, the above-mentioned substituting the sound power spectrum of each fan into the cabin noise prediction model to predict the noise inside the cabin includes:

[0088] Establish a three-dimensional model of the cabin where the noise is to be predicted;

[0089] Input the sound power spectrum of each fan into the model parameters to predict the noise inside the cabin.

[0090] In one implementation, obtaining the fan data arranged at different positions inside the cabin includes the following steps:

[0091] In the initial stage of ship design, determine the ventilation form according to the ventilation requirements at different positions inside the cabin, and the ventilation form includes but is not limited to fresh air, recirculating cooling plus fresh air, and jet ventilation;

[0092] Select the fan model and the number of fans based on different ventilation forms. The fan models include AZN-900 / 350-6, CK 315C, AZN-280 / 160-6, etc.;

[0093] Obtain the fan data for each model, and the fan data can be directly obtained from the fan manufacturer.

[0094] In this application, in the initial stage of ship design, the above-mentioned method for predicting the noise in the cabin is actually applied to the prediction of the noise in the cabin. The specific implementation process is as follows:

[0095] Obtain the fan data arranged in different parts of the cabin and obtain the fan parameters from the fan data, as shown in Table 4:

[0096] Table 4 Fan data and parameters

[0097]

[0098]

[0099] For the No. 1 fan: Since the sound power spectrum of this type of fan is included in the vibration noise database, directly obtain the sound power spectrum, as shown in Table 5:

[0100] Table 5 Sound power spectrum of the No. 1 fan

[0101] Frequency 63 125 250 500 1000 2000 4000 8000 Overall level Sound power dB 82 90 92 95 95 90 86 83 100.3

[0102] For the No. 2 fan: Since neither the fan parameters nor the sound power spectrum is included in the vibration noise database, obtain the sound power spectrum according to the sound power spectrum estimation method for marine fans described in any one of the embodiments in the first aspect. Among them, the fan parameter flow rate Q: 800m 3 / h, pressure T p : 380 Pa, type: centrifugal duct fan, total sound power level: 55.2 dB. Calculate the sound power spectrum values as shown in Table 6:

[0103] Table 6 Sound power spectrum of the No. 2 fan

[0104] Frequency 63 125 250 500 1000 2000 4000 8000 Overall level Sound power dB 26.9 27.9 31.9 36.9 38.9 42.9 46.9 53.9 55.2

[0105] For the No. 3 fan: Since neither the fan parameters nor the sound power spectrum is included in the vibration noise database, obtain the sound power spectrum according to the sound power spectrum estimation method for marine fans described in any one of the embodiments in the first aspect. Obtain the fan parameter flow rate Q: 5000m 3 / h, pressure T p : 500 Pa, type: axial flow fan. Calculate the sound power spectrum values as shown in Table 7:

[0106] Table 7 Sound power spectrum of the No. 3 fan

[0107] Frequency 63 125 250 500 1000 2000 4000 8000 Overall level Sound power dB 93.2 92.2 91.2 91.2 91.2 93.2 97.2 98.2 103.2

[0108] According to the type of fan in the cabin, the sound power spectrum of each fan (Fan No. 1, Fan No. 2, and Fan No. 3) arranged in the cabin is substituted into the cabin noise prediction model to predict the cabin noise.

[0109] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A method for estimating the sound power spectrum of a marine fan, characterized in that, it includes: Obtain the flow rate Q and pressure T from the original parameters of the fan p ; Based on Equation (1): L wf-exp = 10lgQ + 20lgT p + 10 + C wf , the sound power level L at each octave band of the fan is obtained wf- ; where: C wf is the octave band correction value of the air noise of the fan; Substitute the sound power level L of each octave band of the fan wf-ex into formula (2) to calculate the empirical value L of the total sound power level of the fan w-exp ; w 0 is the reference sound power, with a value of 10 -12 ; Check whether the original parameters of the fan include the rated value L of the total sound power level w-man ; If the total sound power level rating L w-man is included, then input the sound power level L wf-exp at each octave band of the fan, the empirical value L w-exp of the total sound power level, and the total sound power level rating L w-man into Equation (3): L wf = L wf-e −(L w-exp − L w-man ), and calculate the actual sound power spectrum L wf of the fan; If the total sound power level rating L w-man is not included, then determine whether the original parameters of the fan include the total sound pressure level rating L P-man ; If it includes the rated value of the overall sound pressure level L P-man , then calculate the rated value of the overall sound power level L w-man according to the conversion formula between the overall sound pressure level and the overall sound power level: Where: S: the area of the measurement surface; S O : 1m 2 ; Then input the octave band sound power level L of the fan wf-exp , the empirical value L of the total sound power level w-exp and the rated value L of the total sound power level into Equation (3): L w-man = L wf -(L wf-exp -(L w-exp -L w-man )) to calculate the actual sound power spectrum L of the fan wf ; If the total sound pressure level rating L is not included P-man , then the sound power level L at each octave band of the fan wf-e is used as the sound power spectrum L of the fan wf .

2. The method for estimating the sound power spectrum of a marine fan according to claim 1, characterized in that, The acquisition of the described C wf includes: obtain the fan type from the original parameters of the fan; Determine the value of C according to the type of the fan wf .

3. The method for estimating the sound power spectrum of a marine fan according to claim 2, characterized in that, the fan types include centrifugal fans and axial fans.

4. A method for predicting the noise in a cabin, characterized in that, it includes: obtain the fan data arranged in different parts of the cabin; obtain the fan parameters from the fan data; judge whether each fan parameter contains a sound power spectrum; if so, obtain the sound power spectrum of the fan; if not, obtain the sound power spectrum according to the method for estimating the sound power spectrum of a marine fan described in any one of claims 1-3 above; substitute the sound power spectrum of each fan into the cabin noise prediction model to predict the noise in the cabin.

5. The method for predicting the noise in a cabin according to claim 4, characterized in that, before the fan parameter does not contain a sound power spectrum and according to the method for estimating the sound power spectrum of a marine fan described in any one of claims 1-3, it further includes: search for fans of the same model in the vibration and noise database; judge whether the fan parameters of the same model contain a sound power spectrum.

6. The method for predicting the noise in a cabin according to claim 4, characterized in that, the substituting the sound power spectrum of each fan into the cabin noise prediction model to predict the noise in the cabin includes: establish a three-dimensional model of the cabin where the noise is to be predicted; input the sound power spectrum of each fan into the model parameters to predict the noise in the cabin.

7. The method for predicting the noise in a cabin according to claim 4, characterized in that, the obtaining the fan data arranged in different parts of the cabin includes: determine the ventilation form according to the ventilation requirements in different parts of the cabin; select the fan model and the number of fans based on different ventilation forms; obtain the fan data of each model.

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