Structure parameter design method for suppressing nonlinear effect of micro-perforated plate
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A non-linear effect, micro-perforated plate technology, applied in the field of sound absorption and noise reduction
Active Publication Date: 2017-09-19
HOHAI UNIV CHANGZHOU
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This method is fundamentally different from the existing method of minimizing linear acoustic resistance and expanding its application to high sound intensity through nonlinear acoustic impedance, and has not been reported yet.
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Embodiment 1
[0117] Example 1: Design and realize the structural parameters of the micro-perforated plate sound absorbing body with nonlinear suppression to 110dB.
[0118] First, in step 1, analyze the frequency spectrum and sound pressure level of the high sound intensity noise field, and determine that the maximum sound pressure level of the actual noise environment is P 0 =110dB and the maximum noise reduction frequency point is f 0 = 2000Hz;
[0119] Later, since 110dB is moderate, considering the production cost, a larger aperture and a smaller perforation rate can be selected first. Therefore, first select d=0.5×10 -3 m, t / d=1, calculated according to the formula (1) to obtain the perforation rate σ=0.0084;
[0120] Then, the known parameters are substituted into formulas (2)-(28) to obtain the cavity depth L c =0.0032m and the curve of acoustic impedance versus incident sound pressure level, such as image 3 shown. observe image 3 , it can be seen that the transition sound ...
Embodiment 2
[0122] Embodiment 2: Design and realize the structural parameters of the micro-perforated plate sound absorbing body with nonlinear suppression to 140dB.
[0123] First, in step 1, analyze the frequency spectrum and sound pressure level of the high sound intensity noise field, and determine that the maximum sound pressure level of the actual noise environment is P 0 =140dB and the maximum noise reduction frequency point is f 0 = 3000Hz;
[0124] Then, since 140dB is larger, you can start with a smaller aperture and a smaller perforation rate. Therefore, first select d=0.1×10 -3 m, t / d=4, calculated according to the formula (1) to obtain the perforation rate σ=0.066;
[0125] Then, the known parameters are substituted into formulas (2)-(28) to obtain the cavity depth L c =0.0218m and the curve of acoustic impedance versus incident sound pressure level, such as Figure 4 shown. observe Figure 4 , it can be seen that the transition sound pressure level at which the nonlin...
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Abstract
The invention discloses a structure parameter design method for suppressing a nonlinear effect of a micro-perforated plate. The method comprises the steps that first, a high-sound-intensity noise field is subjected to frequency spectrum and sound pressure level analysis, and limiting condition parameters and to-be-designed parameters are determined according to frequency domain distribution of noise energy; second, a group of {d,t/d} parameters are selected; third, a corresponding perforation rate sigma is calculated; fourth, a curve of micro-perforated plate structure acoustic impedance Z changing along with an incidence sound pressure level P is drawn through numerical simulation according to a parameter combination {d,t/d,sigma} and a known parameter f<0>; and fifth, the relation curve of the acoustic impedance changing along with the incidence sound pressure level in the third step is observed, and a transformation sound pressure level corresponding to the nonlinear acoustic impedance which starts to work is obtained. According to the method, the nonlinear effect of a sound absorption structure of the micro-perforated plate under high sound intensity is effectively suppressed, so that the micro-perforated plate has good linear sound absorption performance within a given sound pressure level range, and the sound pressure level range which the sound absorption structure of the micro-perforated plate can be effectively applied to is greatly expanded.
Description
technical field [0001] The invention relates to a structural parameter design method for suppressing the nonlinear effect of a micro-perforated plate, and relates to the technical field of sound absorption and noise reduction. Background technique [0002] The sound-absorbing structure of the micro-perforated plate has the advantages of cleanness, light weight, moisture resistance, high temperature resistance, and plate diversity. It is known as the most attractive green and environmentally friendly sound-absorbing material in the 21st century. The sound-absorbing structure of the micro-perforated plate was proposed by Professor Ma Dayou in 1975. After decades of development, the micro-perforated plate structure is under the linear condition of the lower sound pressure level (the sound pressure level SPL is generally less than 100dB, or even smaller ) theoretical model of acoustic impedance and related acoustic design theory have been quite perfect, however, in the applicati...
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