CN103943101A - Acoustical sound absorption module for anechoic tank - Google Patents

Abstract

The invention provides an acoustical sound absorption module for an anechoic tank. An installation plate is provided with a plurality of conical wedges and is a hard polyvinyl chloride plastic plate. The conical wedges are made of sound absorption rubber. The acoustical sound absorption module for the anechoic tank solves the problem of wideband sound absorption of the anechoic tank, can be applied to the anechoic tank and can absorb sounds effectively within the frequency band ranging from 2KHz to 200KHz.

Description

Anechoic tank, acoustics sound absorbing module

Technical field

A kind of anechoic tank, acoustics of the present invention sound absorbing module can be realized sound absorption effectively in wider band limits.

Background technology

Conventionally underwater acoustic measurement belongs to free far-field measurement, and free field is had to very complicated requirement.Natural open waters such as: lake, rivers, large reservoir, gulf, harbour etc. all can be used for free field and measure.But the natural cause impacts such as natural water area climate environment are very large, and measuring table installation is complicated, and cost is higher.Thereby build artificial anechoic tank, and remain the current overwhelming majority and be engaged in R&D institution that underwater sound research and underwater sound equipment produce and the inevitable choice of factory.But along with the use frequency range of underwater sound equipment is expanded to high and low frequency respectively, how in wider band limits, to realize sound absorption effectively, become the important technology problem that anechoic tank, is built.

Summary of the invention

The invention provides a kind of anechoic tank, acoustics sound absorbing module, solved an anechoic tank, broadband sound absorption difficult problem, can be for anechoic tank,, also effectively sound absorption of realization in 2KHZ～200KHZ frequency range.

The technical scheme that the present invention takes is: anechoic tank, acoustics sound absorbing module, and installing plate is provided with a plurality of circular cone wedges, and described installing plate is rigid plastic of polyvinyl chloride plate, and described circular cone wedge is sound absorbent rubber.

Circular cone wedge is evenly distributed on installing plate by 200 every square metre.Described circular cone wedge comprises ovaler cone wedge, shorter circular cone wedge, and described ovaler cone wedge, shorter circular cone wedge are equidistantly interspersed on installing plate.

Described shorter circular cone wedge bottom surface circular diameter φ is 37mm, length: 335mm.Ovaler cone wedge bottom surface circular diameter φ is 50mm, length: 470mm.

Described circular cone wedge partly consists of column part and cone.

Anechoic tank, acoustics sound absorbing module of the present invention can be realized effectively sound absorption for anechoic tank, in 2KHZ～200KHZ frequency range.

Accompanying drawing explanation

Below in conjunction with drawings and Examples, the invention will be further described:

Fig. 1 is perspective view of the present invention;

Fig. 2 is side-looking structural representation of the present invention;

Fig. 3 is circular cone wedge diagrammatic cross-section of the present invention;

Fig. 4 is gradual change absorption layer schematic diagram.

Embodiment

Although the existing very long history of wedge absorber acoustics theory research, does not also set up strict acoustics theory so far, this is the scrambling because of its interface, and strict wave theory is difficult to provide exact solution, can only do approximate treatment.The method of approximate treatment be on xsect wedge material and the acoustical parameters such as characteristic impedance of medium around, by area weighted do certain average after, draw the respective amount of equivalent absorption layer, then according to graded bedding theory, process.Be about to the reflection problems of gradual change absorption layer as solution studied of determining of a wave equation.More famous is exactly that WKB is approximate.The approximate expression of reflection coefficient of gradual change absorption layer of now take is basis, the expression formula of derivation circular cone wedge reflection coefficient.

As shown in Figure 3, L is always degree of producing of circular cone, and d is termination diameter, and L1 is centrum partial-length.

According to WKB criterion, if met gradual change absorption layer at the reflection coefficient of x=0 place (see figure 4) is:

（1-1）

In formula:

Wherein: K represents coefficient of volume compressibility, k represents circular wavenumber.

When circular cone wedge cut elasticity while becoming negligible, the equivalent gradual change absorbent treatment of sound absorption circular cone is:

In formula: n (x)=(xl ₁) ²=u ².U is transition function, is the ratio of the sectional area of circular cone wedge transition portion and the floorage of circular cone wedge, and it is the parameter that unique decision transitional region changes speed.For circular cone wedge, have: ρ ' (0)=0, so formula (1-1) becomes

$V=\frac{\left[\frac{k_0-K_{\left(0\right)}}{k_0+K_{\left(0\right)}}\right]\±e^{2l{\∫}_0^{l}K\left(x\right)\mathrm{dx}}}{1\±\left[\frac{k_0-K_{\left(0\right)}}{k_0+K_{\left(0\right)}}\right]e^{2l{\∫}_0^{l}K\left(x\right)\mathrm{dx}}}---(1-4)$

Wherein: $K^2\left(x\right)=\frac{1}{L_1^2}\left\{{\left(k_0{L}_1\right)}^2\right[1+A\′u+B\′u^4]+\frac{{\mathrm{\ρ}}_1/{\mathrm{\ρ}}_0-1}{1+({\mathrm{\ρ}}_1/{\mathrm{\ρ}}_0-1)u^2}-3\frac{{({\mathrm{\ρ}}_1/{\mathrm{\ρ}}_0-1)}^2}{{[1+]({\mathrm{\ρ}}_1/{\mathrm{\ρ}}_0-1u^2)}^2}\}$

$k^2\left(x\right)=\frac{{\mathrm{\ω}}^2}{c^2\left(x\right)}$

In formula: ρ---represent density;

ρ ₀c ₀---the acoustic impedance of propagation medium;

ρ ₁c ₁---the acoustic impedance of circular cone wedge;

$u=\frac{x}{L_1};$

$A\′=(\frac{{\mathrm{\ρ}}_0{c}_0^2}{{\mathrm{\ρ}}_1{c}_1^2}-1)+(\frac{{\mathrm{\ρ}}_1}{{\mathrm{\ρ}}_0}-1);$

$B\′=(\frac{{\mathrm{\ρ}}_0{c}_0^2}{{\mathrm{\ρ}}_1{c}_1^2}-1)+(\frac{{\mathrm{\ρ}}_1}{{\mathrm{\ρ}}_0}-1);$

For underwater sound wedge, meet so, reflection coefficient be reduced to into:

$\left|V\right|=\exp \{-\mathrm{Im}[2{\∫}_0^{L}K\left(x\right)\mathrm{dx}\left]\right\}---(1-5)$

For formula (1-3), be at 0<x<L ₁the variation of continuous gradation layer draws, at L ₁<x<L, also approximate establishment, through integral and calculating:

$\left|V\right|=\exp \{-\left(k_0{L}_1\right)\mathrm{Im}[\sqrt{A\&prime;+1}+\frac{1}{\sqrt{A}}\ln (\sqrt{A\&prime;}+\sqrt{A\&prime;+1})+2\frac{k_1}{k_0}\left(\frac{L-L_1}{L_1}\right)\left]\right\}---(1-6)$

Anechoic tank, acoustics sound absorbing module design concept:

For anechoic tank,, the sound absorber of function admirable is obviously the prerequisite that guarantees its acoustically effective, but rationally the laying of sound absorber, thus reach best impedance matching, be the important means that realizes pond broadband sound absorption.This can be interpreted as, in low frequency situation, wavelength is greater than the size of single conic section and the distance between them, thereby the numerical value of the equivalent compress coefficient of medium changes along with the number percent of acoustic absorbant area occupied in unit area, thereby select different materials, suitable shape, the sound absorber of size and the distribution of suitable density just capable of realizing impedance matching, make the reflection wave on structural plane very weak; In high frequency situations, sound absorption can be explained with the decay that sound wave is propagated in the waveguide with loss wall.Because cone is separated into many ducts medium, sound wave causes vibration and the deformation of wall while propagating therein, thereby produces strong sound absorption.From above-mentioned analysis, can know, by the broadband sound absorbing module that forms of sound absorption circular cone, its lower frequency limit determines by circular cone length, and upper limiting frequency is determined by the distance between circular cone.

According to above mechanism, anechoic tank, acoustics sound absorbing module of the present invention, as shown in Figure 1, installing plate 1 is provided with a plurality of circular cone wedges 2, and described installing plate 1 is rigid plastic of polyvinyl chloride plate, and described circular cone wedge 2 is sound absorbent rubber.

Described circular cone wedge 2 comprises ovaler cone wedge 2.1, shorter circular cone wedge 2.2, described ovaler cone wedge 2.1, shorter circular cone wedge 2.2 equidistantly, be interspersed on installing plate 1.

Described shorter circular cone wedge 2.2 bottom surface circular diameter φ are 37mm, length: 335mm.Described ovaler cone wedge 2.1 bottom surface circular diameter φ are 50mm, length: 470mm.

Described ovaler cone wedge 2.1, shorter circular cone wedge 2.2 by: column part and cone partly form,

As shown in Figure 2.

The scheme of above-mentioned two kinds of different specification sizes can composite design, and ovaler cone wedge 2.1, shorter circular cone wedge 2.2 mix arrangement by every square metre each 200, and the sound absorbing module after composite design meets the sound absorption requirement in 2KHz～200KHz frequency range.

Anechoic tank, acoustics sound absorbing module of the present invention, sound absorption frequency range is from 2KHz～200KHz.Its sound absorbing capabilities measured value sees the following form:

Frequency (kHz)	Acoustical absorption coefficient	Frequency (kHz)	Acoustical absorption coefficient
				2.0	0.989	25	0.992
2.5	0.991	31.5	0.997
				3.15	0.996	40	0.995
4.0	0.992	50	0.998

5.0	0.993	63	0.999
				6.3	0.994	80	0.999
8.0	0.993	100	0.997
				10.0	0.994	125	0.999
12.5	0.991	160	0.996
				16.0	0.992	180	0.973
20.0	0.995	200	0.955

Claims (7)

1. anechoic tank, acoustics sound absorbing module, is characterized in that, installing plate (1) is provided with a plurality of circular cone wedges (2), and described installing plate (1) is rigid plastic of polyvinyl chloride plate, and described circular cone wedge (2) is sound absorbent rubber.

2. anechoic tank, acoustics sound absorbing module according to claim 1, is characterized in that, circular cone wedge (2) is evenly distributed on installing plate (1) by 200 every square metre.

3. according to anechoic tank, acoustics sound absorbing module described in claim 1 or 2, it is characterized in that, described circular cone wedge (2) comprises ovaler cone wedge (2.1), shorter circular cone wedge (2.2), and described ovaler cone wedge (2.1), shorter circular cone wedge (2.2) are equidistantly interspersed on installing plate (1).

4. anechoic tank, acoustics sound absorbing module according to claim 3, is characterized in that, described shorter circular cone wedge (2.2) bottom surface circular diameter φ is 37mm, length: 335mm.

5. anechoic tank, acoustics sound absorbing module according to claim 3, is characterized in that, described ovaler cone wedge (2.1) bottom surface circular diameter φ is 50mm, length: 470mm.

6. according to anechoic tank, acoustics sound absorbing module described in claim 1 or 2, it is characterized in that, described circular cone wedge (2) partly consists of column part and cone.

7. anechoic tank, acoustics sound absorbing module as described in claim 1～6 any one absorbs sound for anechoic tank, in 2KHZ～200KHZ frequency range.