CN104677657A - Method for measuring acoustic performance of side-by-side sound absorber type silencer - Google Patents

Abstract

The invention provides a simple easy-to-implement and high-measuring-accuracy method for measuring the acoustic performance of a side-by-side sound absorber type silencer by using a conventional laboratory. The method comprises the following steps that (1) a basic unit of a silencer to be measured is determined; (2) a measuring unit capable of entering the conventional laboratory for measurement is set; (3) when the length of the silencer to be measured exceeds the upper limit limited by a conventional laboratory measuring device, the measuring unit corresponding to the silencer to be measured is cut into two different measuring units in different lengths in a simulated way; (4) the measuring units are subjected to sound spreading loss, airflow noise sound power stage and full pressure loss coefficient tests according to a conventional test method. The method has the following advantages that (1) the difficult problem that an ultra-large side-by-side sound absorber type silencer cannot enter the conventional laboratory for measurement is solved; (2) before the side-by-side sound absorber type silencer is installed on site, the variable quantity and the influence of various out-of-control environment factors on the installation site on the silencer equipment parameters can be scientifically and accurately pre-judged.

Description

To the method that sound absorber formula sound suppressor acoustical behavior is side by side measured

Technical field

The present invention relates to a kind of method measuring sound suppressor acoustical behavior, particularly a kind of method measured of sound suppressor of the formula of sound absorber side by side of the unconventional size to Routine Test Lab cannot be entered.

Background technology

Along with the development of economic society, the quick growth of scientific and technological strength and being on the increase of capital construction project, at present, in practical engineering application, need to install a large amount of large-scale (namely referring to the section of complete machine and the large sound suppressor of length dimension) sound absorber formula muffler device side by side, but there are the following problems to carry out measurement to the acoustical behavior of these large-scale sound suppressors:

1) because package size is too large, such large-scale sound suppressor cannot enter Routine Test Lab and measure.

2) if measure in erecting stage, shortcoming is:

A) because this muffler device is in place, namely toilet survey acoustical behavior is not good, cannot carry out adjustment by a relatively large margin yet, namely late;

B) environmental baseline (the uncertain and environmental background noise etc. of space size, shape and reflection characteristic) due to each erecting stage is different, the data measured muffler device acoustical behavior are at the scene subject to the impact of environmental baseline, to survey data uncertainty larger, therefore, these data accurately can not reflect the real internal performance of surveyed muffler device.That is, with the muffler device of a measurement data at the scene, depend merely on site of deployment survey the related data that data and other sound suppressor identify and carry out lateral comparison, be to judge quality therebetween.

3) for large-scale muffler device component being transported to field combinations and completing, usually, need to carry out necessary adjustment according to the objective condition of concrete erecting stage to its incorporating aspects parameter, due to the acoustical behavior data not having sound suppressor itself more accurately to have, therefore, cannot adjust can produce which kind of change to this Muffler Performance described in scientific forecasting.

Summary of the invention

The technical problem to be solved in the present invention be to provide a kind of simple, measure and utilize Routine Test Lab to the ultra-large type that cannot enter this laboratory method measured of sound absorber formula sound suppressor acoustical behavior side by side accurately.

In order to solve the problems of the technologies described above, the technical solution used in the present invention is:

The method measured sound absorber formula sound suppressor acoustical behavior side by side of the present invention, comprises the method for after entering Routine Test Lab, sound suppressor being carried out to conventionally test, further comprising the steps of:

1) before entering Routine Test Lab, determine the elementary cell of the sound suppressor to be measured in practical application, this elementary cell is: when keeping this sound suppressor length constant, along its transversal section by n row × m be about to this sound suppressor simulation be divided into several elementary cells, quantity and the residing position of the transverse shape of each elementary cell, size and contained sound absorber are identical, and described n, m are positive integer;

2) measuring unit that the entered Routine Test Lab corresponding with this sound suppressor carries out measuring is set, this measuring unit is: with described elementary cell for radix by i capable × j row superposition composition, the cross-sectional dimension of this measuring unit is the size that Routine Test Lab measurement mechanism allows to enter, and described i, j are positive integer;

3) when the length of sound suppressor to be measured exceed that Routine Test Lab measurement mechanism limits upper in limited time, be the measuring unit that two length is different by the described measuring unit simulating cut corresponding from this sound suppressor to be measured, be respectively the first length measurement unit and the second length measurement unit, wherein, the length of the first length measurement unit is L ₁, the length of the second length measurement unit is L ₂, be respectively:

First length measurement unit L ₁=l _i+ l ₁+ l _o;

Second length measurement unit L ₂=l _i+ l ₂+ l _o;

l ₂≥2×l ₁；l ₁≥500mm；

L ₂the maximum measurement length that < Routine Test Lab measurement mechanism allows; l _iand l _obe respectively the contained air intake of sound absorber and the length of outlet air end in this sound suppressor elementary cell to be measured;

4) according to the method for described conventionally test to described first length measurement unit L ₁with the second length measurement unit L ₂carry out the test of sound transmission loss, pneumatic noise sound power level and total pressure loss coefficient.

To be this measuring unit cross-sectional dimension be the elementary cell quantity contained in described measuring unit can enter quantity corresponding to elementary cell number contained when Routine Test Lab carries out the higher limit measured.

The elementary cell that the elementary cell of described sound suppressor to be measured and measuring unit comprise is elementary cell transversal section congruence relation.

The sound transmission loss TL of described sound suppressor to be measured is obtained according to following formula _a:

TL _AL＝(TL _M1*l ₂－TL _M2*l ₁)/(l ₂－l ₁)+(TL _M2－TL _M1)*l/(l ₂－l ₁)；

TL _m1it is the sound transmission loss of the first length measurement unit;

TL _m2it is the sound transmission loss of the second length measurement unit;

L is the physical length of sound absorber sound absorption section in sound suppressor to be measured.

The total pressure loss coefficient ξ of described sound suppressor to be measured is obtained according to following formula _a:

ξ _A＝ξ _M,1－(ξ _M,2－ξ _M,1) _*l ₁/(l ₂－l ₁)+(ξ _M,2－ξ _M,1) _*l/(l ₂－l ₁)

ξ _{m, 1}be the first length measurement unit L ₁total pressure loss coefficient;

ξ _{m, 2}be the second length measurement unit L ₂total pressure loss coefficient.

The pneumatic noise sound power level L of the sound suppressor to be measured described in obtaining according to following formula _w,A:

L _W,A＝L _W,M+10log(S _A/S _M)+10log[1+(λ/2H _A)]-10log[1+(λ/2H _M)]

L _w,M: the pneumatic noise sound power level of measuring unit, represents with dB;

S _a: the front face area of sound suppressor to be measured, unit: m ²;

S _m: the front face area of measuring unit, unit: m ²;

H _a: large limit, the transversal section size of sound suppressor to be measured, unit: m;

H _m: large limit, the transversal section size of measuring unit, unit: m;

λ: the wavelength of noise, unit: m;

The elementary cell comprised when elementary cell and four similarity measure unit having entered Routine Test Lab of described sound suppressor to be measured has following relation:

1) be elementary cell transversal section similarity relation;

2) the net inflow area S of the elementary cell of sound suppressor to be measured contained elementary cell in four similarity measure unit is minimum net inflow area S ₁be maximum net inflow area S with elementary cell contained in four similarity measure unit ₂between;

3) and have S ₁< S < S ₂; 0.90≤S ₁/ S ₂during < 1.0;

4) elementary cell that four similarity measure unit comprise has following relation:

A. first similarity measure unit and second similarity measure unit are elementary cell transversal section congruence relation, i.e. elementary cell net inflow area equation therebetween and be described minimum net inflow area S ₁;

B. the 3rd similarity measure unit and the 4th similarity measure unit are elementary cell transversal section congruence relation, i.e. elementary cell net inflow area equation therebetween and be described maximum net inflow area S ₂;

C. first similarity measure unit and the 3rd similarity measure unit are elementary cell transversal section similarity relation and are all the first described length measurement unit, and namely these two similarity measure element lengths are identical;

D. second similarity measure unit and the 4th similarity measure unit are elementary cell transversal section similarity relation and are the second described length measurement unit, and namely these two similarity measure element lengths are identical;

Obtain the sound transmission loss TL of described sound suppressor to be measured in accordance with the following methods _a:

TL _A＝TL _M,S1+(TL _M,S1－TL _M,S2)*(S－S ₁)/(S ₁－S ₂)

TL _M,S1＝(TL _M,L1,S1*l ₂－TL _M,L2,S1*l ₁)/(l ₂－l ₁)+(TL _M,L2,S1－TL _M,L1,S1)*l/(l ₂－l ₁)；

TL _M,S2＝(TL _M,L1,S2*l ₂－TL _M,L2,S2*l ₁)/(l ₂－l ₁)+(TL _M,L2,S2－TL _M,L1,S2)*l/(l ₂－l ₁)；

TL _{m, S1}: for net inflow area is S ₁, sound absorption length is the sound transmission loss of the sound suppressor of l, represents with dB;

TL _{m, S2}: for net inflow area is S ₂, sound absorption length is the sound transmission loss of the sound suppressor of l, represents with dB;

TL _{m, L1, S1}: for first-phase is like the sound transmission loss of measuring unit, represent with dB;

TL _{m, L2, S1}: for second-phase is like the sound transmission loss of measuring unit, represent with dB;

TL _{m, L1, S2}: for third phase is like the sound transmission loss of measuring unit, represent with dB;

TL _{m, L2, S2}: the sound transmission loss being the 4th similarity measure unit, represents with dB;

TL _a: the sound transmission loss of sound suppressor to be measured, represents with dB;

S: be the net inflow area of the elementary cell of sound suppressor to be measured, unit: m ²;

S ₁: for first-phase is like measuring unit and the second-phase net inflow area like elementary cell corresponding to measuring unit, unit: m ²;

S ₂: for third phase is like the net inflow area of measuring unit and elementary cell corresponding to the 4th similarity measure unit, unit: m ²;

L: be the physical length of sound suppressor sound absorption section to be measured;

L ₁: for first-phase is like measuring unit and the third phase length like measuring unit sound absorption section;

L ₂: for second-phase like measuring unit and the 4th similarity measure unit sound absorption section length.

When sound suppressor length L to be measured is the length that can enter Routine Test Lab, arrange in the following manner:

1) getting with sound suppressor to be measured is the 5th similarity measure unit and the 6th similarity measure unit of elementary cell transversal section similarity relation;

2) the net inflow area S of the net inflow area S of the elementary cell of sound suppressor to be measured elementary cell contained by the 5th similarity measure unit ₁with the net inflow area S of elementary cell contained in the 6th similarity measure unit ₂between;

3) and have S ₁< S < S ₂; 0.90≤S ₁/ S ₂during < 1.0;

4) length of the 5th similarity measure unit is identical with sound suppressor length to be measured;

5) length of the 6th similarity measure unit is identical with sound suppressor length to be measured;

Obtain the sound transmission loss TL of described sound suppressor to be measured in accordance with the following methods _a:

TL _A＝TL _M,S1+(TL _M,S1－TL _M,S2)*(S－S ₁)/(S ₁－S ₂)

TL _{m, S1}: the sound transmission loss being the 5th similarity measure unit, represents with dB;

TL _{m, S2}: the sound transmission loss being the 6th similarity measure unit, represents with dB;

TL _a: be the sound transmission loss of sound suppressor to be measured, represent with dB;

S: be the net inflow area of the elementary cell of sound suppressor to be measured, unit: m ²;

S ₁: the net inflow area being the elementary cell of the 5th similarity measure unit, unit: m ²;

S ₂: the net inflow area being the elementary cell of the 6th similarity measure unit, unit: m ²;

L: be the physical length of sound suppressor sound absorption section to be measured.

The elementary cell comprised when elementary cell and two similarity measure unit having entered Routine Test Lab of described sound suppressor to be measured has following relation:

1) be elementary cell transversal section similarity relation;

2) the net inflow area S of the elementary cell of sound suppressor to be measured is between the net inflow area S of first-phase like elementary cell contained by measuring unit ₁with the net inflow area S of second-phase like elementary cell contained in measuring unit ₂between;

3) and have S ₁< S < S ₂; 0.90≤S ₁/ S ₂during < 1.0;

Obtain the pneumatic noise sound power level L of described sound suppressor to be measured in accordance with the following methods _{w, A:}

L _W,A＝L _W.M.S+10log ₁₀N＝L _W,M,S1-(L _W,M,S1-L _W,M,S2)*(log ₁₀S-log ₁₀S ₁)/(log ₁₀S ₂-log ₁₀S ₁)+10log ₁₀N

L _w,A: be the pneumatic noise sound power level of sound suppressor to be measured, represent with dB;

L _{w, M, S1}: be the pneumatic noise sound power level of E measuring unit, represent with dB;

L _{w, M, S2}: be the pneumatic noise sound power level of F measuring unit, represent with dB;

N: the ratio of elementary cell that sound suppressor to be measured comprises sum and the number of elementary cell contained by described test cell;

S: the net inflow area of the elementary cell of sound suppressor to be measured, unit: m ²;

S ₁: for first-phase is like the net inflow area of the elementary cell contained by measuring unit, unit: m ²;

S ₂: for second-phase is like the net inflow area of the elementary cell contained by measuring unit, unit: m ².

The elementary cell comprised when elementary cell and four similarity measure unit having entered Routine Test Lab of described sound suppressor to be measured has following relation:

1) be elementary cell transversal section similarity relation;

2) the net inflow area S of the elementary cell of sound suppressor to be measured contained elementary cell in four similarity measure unit is minimum net inflow area S ₁be maximum net inflow area S with elementary cell contained in four similarity measure unit ₂between;

3) S ₁< S < S ₂; 0.90≤S ₁/ S ₂during < 1.0;

4) elementary cell that four similarity measure unit comprise has following relation:

A. first similarity measure unit and second similarity measure unit are elementary cell transversal section congruence relation, i.e. elementary cell net inflow area equation therebetween and be described minimum net inflow area S ₁;

B. the 3rd similarity measure unit and the 4th similarity measure unit are elementary cell transversal section congruence relation, i.e. elementary cell net inflow area equation therebetween and be described maximum net inflow area S ₂;

C. first similarity measure unit and the 3rd similarity measure unit are elementary cell transversal section similarity relation and are all the first described length measurement unit, and namely these two similarity measure element lengths are identical;

D. second similarity measure unit and the 4th similarity measure unit are elementary cell transversal section similarity relation and are the second described length measurement unit, and namely these two similarity measure element lengths are identical;

Obtain the total pressure loss coefficient ξ of described sound suppressor to be measured in accordance with the following methods _{a, r, l}:

Or,

ξ _{m, p, 1}: for first-phase is like the total pressure loss coefficient of measuring unit;

ξ _{m, p, 2}: for second-phase is like the total pressure loss coefficient of measuring unit;

ξ _{m, q, 1}: for third phase is like the total pressure loss coefficient of measuring unit;

ξ _{m, q, 2}: the total pressure loss coefficient being the 4th similarity measure unit;

P: be the net inflow area ratio of first and second similarity measure unit; P=S ₁/ (S ₁+ S ₀);

Q: be the net inflow area ratio of third and fourth similarity measure unit; Q=S ₂/ (S ₂+ S ₀)

R: be the net inflow area ratio of sound suppressor to be measured; R=S/ (S+S ₀)

S: be the net inflow area of the elementary cell of sound suppressor to be measured, unit: m ²;

S ₁: the net inflow area of the elementary cell contained by first and second similarity measure unit, unit: m ²;

S ₂: the net inflow area of the elementary cell contained by third and fourth similarity measure unit, unit: m ²;

S ₀: the elementary cell blocking area separately contained by four similarity measure unit and sound suppressor to be measured, unit: m ²; ;

L: be the physical length of sound suppressor sound absorption section to be measured;

L ₁: the length being first and third similarity measure unit sound absorption section;

L ₂: the length being second, four similarity measure unit sound absorption sections.

The simulation of the transversal section of the to be measured large-scale sound suppressor in practical application is divided into several elementary cells by the present invention, then determines to enter according to this elementary cell measuring unit that Routine Test Lab measurement mechanism carries out testing and this measuring unit carried out to the test of acoustical behavior.The acoustical behavior data of the associated acoustic performance data of sound suppressor to be measured and other the large-scale sound suppressor with this sound suppressor transversal section to be measured similar conditions are obtained by the relevant test data of this measuring unit.That is:

1) by carrying out the test of sound transmission loss, pneumatic noise sound power level and total pressure loss coefficient to the sound suppressor elementary cell to be measured measuring unit that is the entered Routine Test Lab of elementary cell congruence relation, the sound transmission loss of this sound suppressor to be measured, pneumatic noise sound power level and total pressure loss coefficient is obtained.

2) when the length of sound suppressor to be measured exceedes the maximum measurement length of normal experiment chamber device permission, the first length measurement unit and the second length measurement unit is divided into by simulating along its length with this sound suppressor elementary cell to be measured measuring unit that is elementary cell congruence relation, again by carrying out the test of sound transmission loss, pneumatic noise sound power level and total pressure loss coefficient to the first length measurement unit and the second length measurement unit, obtain the sound transmission loss of the sound suppressor to be measured of random length, pneumatic noise sound power level and total pressure loss coefficient.

3) when two have entered Routine Test Lab and first measuring unit of elementary cell similarity relation has with second measuring unit each other: (1) first measuring unit is identical with the length of second measuring unit and all exceed the upper limit that Routine Test Lab measurement mechanism limits; The net inflow area S of (2) first measuring unit elementary cells ₁with the net inflow area S of second measuring unit elementary cell ₂, meet: 0.90≤S ₁/ S ₂during < 1.0 relation, by carrying out the test of sound transmission loss, pneumatic noise sound power level and total pressure loss coefficient to first measuring unit and second measuring unit, obtain elementary cell and first measuring unit and second measuring unit each other elementary cell similarity relation and net inflow area S meet: S ₁< S < S ₂; 0.90≤S ₁/ S ₂the sound transmission loss of other sound suppressor to be measured of < 1.0, pneumatic noise sound power level and total pressure loss coefficient.

Method of the present invention has following application advantage:

1) for the large-scale formula of sound absorber side by side muffler device, solve and need not be moved into the difficult problem that Routine Test Lab still can obtain its accurate acoustical behavior data;

2) because the associated acoustic performance data that obtained muffler device is intrinsic is more accurate, so, before this sound suppressor is installed at the scene, can science and accurately the various uncontrollable environmental factor in anticipation erecting stage on this muffler device parameter produce impact and variable quantity.

Accompanying drawing explanation

Fig. 1 is one of sound suppressor schematic cross-sectional view.

Fig. 2 is sound suppressor schematic cross-sectional view two.

Fig. 3 is sound suppressor schematic cross-sectional view three.

Fig. 4 be Fig. 1,2 schematic longitudinal section.

Fig. 5 is the schematic longitudinal section of Fig. 3.

Fig. 6 is single sound absorber schematic longitudinal section.

Noise elimination transversal section to be measured is cut into the elementary cell schematic diagram after some parts by Fig. 7.

Fig. 8 is by row by the measuring unit schematic diagram that row are stackable by elementary cell.

Fig. 9 is discontinuous decay D in the derivation of equation of the present invention _swith the variation relation curve map of net inflow area S.

Embodiment

The method that sound absorber formula sound suppressor acoustical behavior is side by side measured of the present invention, the acoustical behavior parameter of Routine Test Lab proving installation to sound absorber sound suppressor side by side is mainly utilized to measure, this is the transverse direction of sound absorber sound suppressor or longitudinal size side by side, the dimensions that enters can be specified for Routine Test Lab, also can for exceeding the dimensions that Routine Test Lab specifies to enter.

Sound absorber formula sound suppressor side by side, refers to the sound suppressor meeting following 3 features:

1) version of sound suppressor is by one or more sound absorbers, and in 1 dimension or 2 dimension directions, matrix launches parallel arranged composition; As shown in Figure 1, 2, 3, typical vertical section as shown in Figure 4,5 in its typical transversal section;

2) acoustic attenuation performance of sound suppressor, by the acoustic impedance of sound absorber sound absorption section surface, and the arrangement pitches of sound absorber determines, each sound absorber is made up of along sound suppressor length direction three parts, be respectively windward side, sound absorption section and outlet air end as shown in Figure 6, usually, the length of sound absorber is the length of sound suppressor;

3) aerodynamic quality of sound suppressor, i.e. pneumatic noise and pitot loss, determined by the number of the arrangement (density) of the two ends geometric configuration of sound absorber and surfaceness and sound absorber, spacing.

The measuring method of current ventilation silencer both domestic and external, is mainly following three kinds of methods:

1) ASTM E477/ISO 7235/GBT 25516; The laboratory measurement method insertion loss of acoustics pipeline silencer and air channel terminal units, pneumatic noise and pitot loss; GBT 4760 acoustic muffler measuring method;

2) ISO 11691/GBT 16405; Insertion loss surveying laboratory simplified method under acoustics pipeline silencer airless state;

3) ISO 11820/GBT 19512; Acoustic muffler in-site measurement;

The major parameter of ventilation silencer performance is: sound deadening capacity (insertion loss/sound transmission loss)/reproduced air-flow noise/pressure loss (resistance/resistance coefficient).Sound suppressor measuring method of the prior art, it is all the measurement of the sound suppressor complete machine based on independent completion, although the annex E of ISO 7235/GBT 25516 also describes the indirect inspection scheme of getting the test of specific section, but the indirect measurement method proposed with the present invention, on the extensive of range of application and versatility, there is the difference of matter.

One, each nominal definition in method of the present invention:

1, elementary cell

When keeping the sound suppressor length to be measured in practical application constant, along its transversal section by this sound suppressor simulating cut to be measured, obtain some pieces of fritter section elements (namely this elementary cell is have to determine transversal section and the unit with this sound suppressor equal length to be measured), each elementary cell transverse shape, size is identical and the position that its sound absorber comprised is how many and residing is also identical, conversely, in units of this elementary cell, horizontal continuous arrangement n row, identical sound suppressor of sound suppressor to be measured can be restored to this after vertical continuous arrangement m capable (n and m is positive integer), this fritter section elements is defined as the elementary cell (as shown in Figure 7) of this sound suppressor to be measured.

2, measuring unit

As shown in Figure 8, with the described elementary cell of sound suppressor to be measured for radix, by i capable × j arranges (i, j are positive integer) array and forms several assembled units, such as: i is capable × j row equal 1 × 1,1 × 2,2 × 2,2 × 3,3 × 3 etc. respectively.In these several assembled units, choose one group or two groups of cross-sectional dimensions can enter assembled unit that Routine Test Lab proving installation carries out the testing measuring unit as this sound suppressor to be measured.The preferred measuring unit of the present invention is the more assembled unit of the elementary cell that comprises.

3, sound absorber congruence

According to the definition of the aforesaid formula of sound absorber side by side sound suppressor, all sound absorber structures in same sound suppressor, size are all identical; When comparing for two sound suppressors, then there will be different situations.When the sound absorber in two sound suppressors compared meets the following conditions, then judge that the sound absorber in these two sound suppressors is congruent as sound absorber:

1) transverse shape of sound absorber is identical with size;

2) geometric configuration of the air intake of sound absorber is identical with size, and surfaceness is identical;

3) geometric configuration of the outlet air end of sound absorber is identical with size, and surfaceness is identical;

4) the vertical section shape of the sound absorption section of sound absorber is identical with size, and surfaceness is identical and surperficial acoustic impedance is identical;

5) sound absorber sound absorption segment length is identical.

4, sound absorber is similar

The length of two sound absorbers only section of sound absorption is not identical, and other Rule of judgment is identical with described sound absorber congruence.

5, elementary cell transversal section congruence

When elementary cell transversal section for two sound suppressors compares, when meeting the following conditions, then judge that the elementary cell transversal section in these two sound suppressors is congruent as elementary cell transversal section:

1) transverse shape, size are identical;

2) quantity of the sound absorber comprised is identical;

3) sound absorber congruence or similar;

4) position of sound absorber in transversal section is identical.

6, elementary cell transversal section is similar

When elementary cell transversal section for two sound suppressors compares, when meeting the following conditions, then judge that the elementary cell transversal section in these two sound suppressors is similar as elementary cell transversal section:

1) transverse shape; Be rectangle, the ratio of width to height is equal;

2) transversal section lateral dimension and vertical dimension is proportional zooms in or out;

3) quantity of the sound absorber comprised is identical;

4) sound absorber congruence or similar;

5) position of sound absorber in transversal section with central, transverse axis and center vertical pivot symmetrical;

6) the net inflow area ratio of transversal section is between 0.9 to 1.0.

7, elementary cell congruence

For the elementary cell of two sound suppressors, when meeting the following conditions, then judge that the elementary cell of these two sound suppressors is as elementary cell congruence:

1) be elementary cell transversal section congruence relation;

2) sound absorber comprised is sound absorber congruence relation.

When two elementary cells are elementary cell congruence relation, its front face area is equal, and blocking area is equal, net inflow area equation, and sound absorption girth is equal, and absorption area is equal.

8, elementary cell is similar

For the elementary cell of two sound suppressors, when meeting the following conditions, then judge that the elementary cell of these two sound suppressors is similar as elementary cell:

1) elementary cell is elementary cell transversal section similarity relation;

2) sound absorber comprised is sound absorber congruence or similarity relation.

When two elementary cells are elementary cell similarity relation, not etc., not etc., blocking area is inequal, and sound absorption girth is equal for net inflow area for its front face area.

9, the corresponding relation for sound suppressor length to be measured and measuring unit has the following two kinds to set:

1) isometric sound absorber measuring unit

If the length of sound suppressor to be measured is less than or equal to the maximum length allowing to enter Routine Test Lab measurement, then corresponding with it measuring unit is isometric sound absorber measuring unit.The length of namely described measuring unit preferentially selects this length.That is, the measurement maximum length in laboratory is L _mAX, the length of the sound suppressor to be measured of practical application is L, L≤L _mAX, then can directly using the length of the length L of sound suppressor to be measured as measuring unit.

2) overlength sound absorber measuring unit

Prescribe a time limit if the length of sound suppressor to be measured exceeds the upper of Routine Test Lab measurement mechanism restriction, then the length of sound absorber sound absorption section in the measuring unit corresponding with it can be divided into two parts, be respectively the first sound absorption section l ₁with the second sound absorption section l ₂, wherein, the first sound absorption section l ₁length be not less than Routine Test Lab measurement mechanism allow test minimum standard length (being generally 500mm), second sound absorption section l ₂length be not less than the first sound absorption section l ₁the twice of length;

Determine to absorb sound with described first section l again ₁the first corresponding length measurement unit L ₁and to absorb sound section l with described second ₂the second corresponding length measurement unit L ₂, wherein,

First length measurement unit L ₁=l _i+ l ₁+ l _o;

Second length measurement unit L ₂=l _i+ l ₂+ l _o;

L ₂the maximum measurement length that < Routine Test Lab measurement mechanism allows; l _iand l _obe respectively the contained air intake of sound absorber and the length of outlet air end in this sound suppressor elementary cell.

Two, the test of acoustical behavior is carried out and the associated acoustic performance data of presumption acquisition sound suppressor to be measured to described measuring unit

One) sound transmission loss/TL

1, when the elementary cell of the measuring unit and sound suppressor to be measured that enter laboratory is elementary cell congruence relation and its length is isometric sound absorber measuring unit, the sound transmission loss TL of sound suppressor to be measured _afor:

TL _A＝TL _M

TL _a: the sound transmission loss of the sound suppressor to be measured in practical application, represents with dB;

TL _m: enter the sound transmission loss that the measuring unit tested is carried out in laboratory, represent with dB;

2, when the elementary cell of the measuring unit and sound suppressor to be measured that enter laboratory is elementary cell transversal section congruence relation and its length not etc. time, then the sound transmission loss TL of sound suppressor to be measured _a(representing with dB) is:

$T{L}_A=T{L}_M=\frac{T{L}_{M,1}\&CenterDot;l_2-T{L}_{M,2}\&CenterDot;l_1}{l_2-l_1}+\frac{T{L}_{M,2}-T{L}_{M,1}}{l_2-l_1}\&CenterDot;l$

TL _{m, 1}: be described first length measurement unit L ₁sound transmission loss, represent with dB;

TL _{m, 2}: be described second length measurement unit L ₂sound transmission loss, represent with dB;

L: be the physical length of sound absorber sound absorption section in sound suppressor to be measured, unit: m.

L ₁: be the length of described first length measurement unit sound absorption section;

L ₂: be the length of described second length measurement unit sound absorption section.

3, the present invention is by measuring four measuring units with elementary cell similarity relation, obtains the sound transmission loss of elementary cell and this four measuring units sound suppressor to be measured of elementary cell similarity relation each other.

That is: the elementary cell comprised when elementary cell and four similarity measure unit having entered Routine Test Lab of described sound suppressor to be measured has following relation:

1) be elementary cell transversal section similarity relation;

2) the net inflow area S of the elementary cell of sound suppressor to be measured contained elementary cell in four similarity measure unit is minimum net inflow area S ₁be maximum net inflow area S with elementary cell contained in four similarity measure unit ₂between;

3) and have S ₁< S < S ₂; 0.90≤S ₁/ S ₂during < 1.0;

4) elementary cell that four similarity measure unit comprise has following relation:

A. first similarity measure unit and second similarity measure unit are elementary cell transversal section congruence relation, i.e. elementary cell net inflow area equation therebetween and be described minimum net inflow area S ₁;

B. the 3rd similarity measure unit and the 4th similarity measure unit are elementary cell transversal section congruence relation, i.e. elementary cell net inflow area equation therebetween and be described maximum net inflow area S ₂;

C. first similarity measure unit and the 3rd similarity measure unit are elementary cell transversal section similarity relation and are all the first described length measurement unit, and namely these two similarity measure element lengths are identical;

D. second similarity measure unit and the 4th similarity measure unit are elementary cell transversal section similarity relation and are the second described length measurement unit, and namely these two similarity measure element lengths are identical;

Obtain the sound transmission loss TL of described sound suppressor to be measured in accordance with the following methods _a:

TL _A＝TL _M,S1+(TL _M,S1－TL _M,S2)*(S－S ₁)/(S ₁－S ₂)

TL _M,S1＝(TL _M,L1,S1*l ₂－TL _M,L2,S1*l ₁)/(l ₂－l ₁)+(TL _M,L2,S1－TL _M,L1,S1)*l/(l ₂－l ₁)；

TL _M,S2＝(TL _M,L1,S2*l ₂－TL _M,L2,S2*l ₁)/(l ₂－l ₁)+(TL _M,L2,S2－TL _M,L1,S2)*l/(l ₂－l ₁)；

TL _{m, S1}: for net inflow area is S ₁, sound absorption length is the sound transmission loss of the sound suppressor of l, represents with dB;

TL _{m, S2}: for net inflow area is S ₂, sound absorption length is the sound transmission loss of the sound suppressor of l, represents with dB;

TL _{m, L1, S1}: for first-phase is like the sound transmission loss of measuring unit, represent with dB;

TL _{m, L2, S1}: for second-phase is like the sound transmission loss of measuring unit, represent with dB;

TL _{m, L1, S2}: for third phase is like the sound transmission loss of measuring unit, represent with dB;

TL _{m, L2, S2}: the sound transmission loss being the 4th similarity measure unit, represents with dB;

TL _a: the sound transmission loss of sound suppressor to be measured, represents with dB;

S: be the net inflow area of the elementary cell of sound suppressor to be measured, unit: m ²;

S ₁: for first-phase is like measuring unit and the second-phase net inflow area like elementary cell corresponding to measuring unit, unit: m ²;

S ₂: for third phase is like the net inflow area of measuring unit and elementary cell corresponding to the 4th similarity measure unit, unit: m ²;

L: be the physical length of sound suppressor sound absorption section to be measured;

L ₁: for first-phase is like measuring unit and the third phase length like measuring unit sound absorption section;

L ₂: for second-phase like measuring unit and the 4th similarity measure unit sound absorption section length.

4, the present invention is by measuring two measuring units with elementary cell similarity relation, obtains the sound transmission loss of elementary cell and this two measuring units sound suppressor to be measured of elementary cell similarity relation each other.

That is: when the elementary cell of described sound suppressor to be measured has following relation with two other the 5th similarity measure unit that sound absorber formula sound suppressor is corresponding side by side having entered Routine Test Lab and the elementary cell that the 6th similarity measure unit comprises:

1) be elementary cell transversal section similarity relation;

2) the net inflow area S of the elementary cell of sound suppressor to be measured and first-phase are like the net inflow area S of measuring unit elementary cell ₁with the net inflow area S of second-phase like measuring unit elementary cell ₂, meet: S ₁< S < S ₂; 0.90≤S ₁/ S ₂during < 1.0;

3) length of sound suppressor to be measured is no more than Routine Test Lab measurement mechanism when specifying the higher limit entered;

Obtain the sound transmission loss TL of this sound suppressor to be measured in accordance with the following methods _a:

TL _A＝TL _M,S1+(TL _M,S1－TL _M,S2)*(S－S ₁)/(S ₁－S ₂)

TL _{m, S1}: the sound transmission loss being the 5th similarity measure unit, represents with dB;

TL _{m, S2}: the sound transmission loss being the 6th similarity measure unit, represents with dB;

TL _a: be the sound transmission loss of sound suppressor to be measured, represent with dB;

S: be the net inflow area of the elementary cell of sound suppressor to be measured, unit: m ²;

S ₁: the net inflow area being the elementary cell of the 5th similarity measure unit, unit: m ²;

S ₂: the net inflow area being the elementary cell of the 6th similarity measure unit, unit: m ²;

L: be the physical length of sound suppressor sound absorption section to be measured.

Two) pneumatic noise sound power level/L _w

1, normal conditions, the pneumatic noise sound power level/L of sound suppressor _wfor:

$L_W=B+10\&CenterDot;\log \{\frac{\mathrm{pcS}}{W_0}\&CenterDot;{\left(\frac{v}{c}\right)}^6\&CenterDot;[1+{\left(\frac{c}{2\mathrm{fH}}\right)}^2\left]\right\}-10\&CenterDot;\log [1+{\left(\frac{\mathrm{f\&delta;}}{v}\right)}^2]$

The constant that B-sound suppressor pneumatic structure (shape and physical dimension) associates, represents with dB;

The inner Peak Flow Rate (m/s) of v-sound suppressor;

C-velocity of sound (m/s);

Static pressure (Pa) in p-sound suppressor;

Sectional area (the m of s-Peak Flow Rate point ²);

F-frequency (Hz);

The maximal side of H-sound suppressor section, unit is rice (m);

δ-regenerated noise is at the characteristic parameter of high band, and unit is rice (m);

W ₀-1 (watt);

According to above-mentioned formula, in theory, as long as measure two groups of different wind speed v data, just can obtain B and δ, thus can according to other parameters of concrete sound suppressor, S, H, obtain different frequency f, pneumatic noise sound power level.

When actual measurement, a series of data of multiple wind speed can be measured, return B and δ parameter values more reliably.

By measuring the similar measuring unit of two elementary cells, the relation of B and δ parameter values and net inflow area ratio can be found, thus the pneumatic noise sound power level with the measuring unit measured other sound suppressor of elementary cell similarity relation each other can be obtained further.

2, when the elementary cell of the measuring unit and sound suppressor to be measured that enter laboratory is elementary cell congruence relation, now face velocity is equal, the pneumatic noise sound power level L of sound suppressor to be measured _wcan be reduced to:

$L_{W,A}=L_{W,M}+10\log \left(\frac{S_A}{S_M}\right)+10\log [1+\left(\frac{\mathrm{\&lambda;}}{2H_A}\right)]-10\log [1+\left(\frac{\mathrm{\&lambda;}}{2H_M}\right)]$

L _{w, M}: the pneumatic noise sound power level of measuring unit, represents with dB;

S _a: the front face area of sound suppressor to be measured, unit: m ²;

S _m: the front face area of measuring unit, unit: m ²;

H _a: large limit, the transversal section size of sound suppressor to be measured, unit: m;

H _m: large limit, the transversal section size of measuring unit, unit: m;

λ: the wavelength of noise, unit: m.

3, the present invention is by measuring two measuring units with elementary cell similarity relation, obtains the pneumatic noise sound power level of elementary cell and this two measuring units sound suppressor to be measured of elementary cell similarity relation each other.

That is: the elementary cell comprised when elementary cell and two similarity measure unit having entered Routine Test Lab of described sound suppressor to be measured has following relation:

1) be elementary cell transversal section similarity relation;

2) the net inflow area S of the elementary cell of sound suppressor to be measured is between the net inflow area S of first-phase like elementary cell contained by measuring unit ₁with the net inflow area S of second-phase like elementary cell contained in measuring unit ₂between;

3) and have S ₁< S < S ₂; 0.0≤S ₁/ S ₂during < 1.0;

Obtain the pneumatic noise sound power level L of described sound suppressor to be measured in accordance with the following methods _w.M.S:

$L_{W,A}=L_{W,M,S}+10\&CenterDot;{\log }_{10}N=L_{{W,M,S}_1}-\frac{L_{{W,M,S}_1}-L_{{W,M,S}_2}}{{\log }_{10}{S}_2-{\log }_{10}{S}_1}\&CenterDot;({\log }_{10}S-{\log }_{10}{S}_1)+10\&CenterDot;{\log }_{10}N$

L _w,A: be the pneumatic noise sound power level of sound suppressor to be measured, represent with dB;

L _{w, M, S1}: be the pneumatic noise sound power level of E measuring unit, represent with dB;

L _{w, M, S2}: be the pneumatic noise sound power level of F measuring unit, represent with dB;

N: the ratio of elementary cell that sound suppressor to be measured comprises sum and the number of elementary cell contained by described test cell;

S: the net inflow area of the elementary cell of sound suppressor to be measured, unit: m ²;

S ₁: for first-phase is like the net inflow area of the elementary cell contained by measuring unit, unit: m ²;

S ₂: for second-phase is like the net inflow area of the elementary cell contained by measuring unit, unit: m ².

Three) total pressure loss coefficient/ξ

1, when the elementary cell of the measuring unit and sound suppressor to be measured that enter laboratory is elementary cell congruence relation, the total pressure loss coefficient ξ of sound suppressor to be measured _afor:

ξ _A＝ξ _M

ξ _a: the total pressure loss coefficient of sound suppressor to be measured, dimensionless;

ξ _m: the total pressure loss coefficient of measuring unit, dimensionless.

2, when the elementary cell of the measuring unit and sound suppressor to be measured that enter laboratory is elementary cell transversal section congruence relation and its length not etc. time, then the total pressure loss coefficient ξ of sound suppressor to be measured _afor:

${\mathrm{\&xi;}}_A={\mathrm{\&xi;}}_{M,1}-\frac{{\mathrm{\&xi;}}_{M,2}-{\mathrm{\&xi;}}_{M,1}}{l_2-l_1}\&CenterDot;l_1+\frac{{\mathrm{\&xi;}}_{M,2}-{\mathrm{\&xi;}}_{M,1}}{l_2-l_1}\&CenterDot;l$

ξ _{m, 1}: sound absorption segment length is l ₁the total pressure loss coefficient of measuring unit, dimensionless;

ξ _{m, 2}: for sound absorption segment length is l ₂the total pressure loss coefficient of measuring unit, dimensionless;

L: be the length of sound absorber sound absorption section in sound suppressor to be measured, unit: m.

3, the present invention is by measuring four measuring units with elementary cell similarity relation, obtains the total pressure loss coefficient of elementary cell and this four measuring units sound suppressor to be measured of elementary cell similarity relation each other.

That is: the elementary cell comprised when elementary cell and four similarity measure unit having entered Routine Test Lab of described sound suppressor to be measured has following relation:

1) be elementary cell transversal section similarity relation;

2) the net inflow area S of the elementary cell of sound suppressor to be measured contained elementary cell in four similarity measure unit is minimum net inflow area S ₁be maximum net inflow area S with elementary cell contained in four similarity measure unit ₂between;

3) S ₁< S < S ₂; 0.90≤S ₁/ S ₂during < 1.0;

4) elementary cell that four similarity measure unit comprise has following relation:

A. first similarity measure unit and second similarity measure unit are elementary cell transversal section congruence relation, i.e. elementary cell net inflow area equation therebetween and be described minimum net inflow area S ₁;

B. the 3rd similarity measure unit and the 4th similarity measure unit are elementary cell transversal section congruence relation, i.e. elementary cell net inflow area equation therebetween and be described maximum net inflow area S ₂;

C. first similarity measure unit and the 3rd similarity measure unit are elementary cell transversal section similarity relation and are all the first described length measurement unit, and namely these two similarity measure element lengths are identical;

D. second similarity measure unit and the 4th similarity measure unit are elementary cell transversal section similarity relation and are the second described length measurement unit, and namely these two similarity measure element lengths are identical;

Obtain the total pressure loss coefficient ξ of described sound suppressor to be measured in accordance with the following methods _{a, r, l}:

Or,

ξ _{m, p, 1}: for first-phase is like the total pressure loss coefficient of measuring unit;

ξ _{m, p, 2}: for second-phase is like the total pressure loss coefficient of measuring unit;

ξ _{m, q, 1}: for third phase is like the total pressure loss coefficient of measuring unit;

ξ _{m, q, 2}: the total pressure loss coefficient being the 4th similarity measure unit;

P: be the net inflow area ratio of first and second similarity measure unit; P=S ₁/ (S ₁+ S ₀);

Q: be the net inflow area ratio of third and fourth similarity measure unit; Q=S ₂/ (S ₂+ S ₀)

R: be the net inflow area ratio of sound suppressor to be measured; R=S/ (S+S ₀)

S: be the net inflow area of the elementary cell of sound suppressor to be measured, unit: m ²;

S ₁: the net inflow area of the elementary cell contained by first and second similarity measure unit, unit: m ²;

S ₂: the net inflow area of the elementary cell contained by third and fourth similarity measure unit, unit: m ²;

S ₀: the elementary cell blocking area separately contained by four similarity measure unit and sound suppressor to be measured, unit: m ²(note: elementary cell transversal section is similar each other due to the elementary cell of elementary cell and the sound suppressor to be measured of four measuring units, and therefore its blocking area is equal);

L: be the physical length of sound suppressor sound absorption section to be measured;

L ₁: the length being first and third similarity measure unit sound absorption section;

L ₂: the length being second, four similarity measure unit sound absorption sections.

Each formula theoretical foundation in claims of the present invention:

1. the derivation of equation of claim 4

$T{L}_M=\frac{T{L}_{M,1}\&CenterDot;l_2-T{L}_{M,2}\&CenterDot;l_1}{l_2-l_1}+\frac{T{L}_{M,2}-T{L}_{M,1}}{l_2-l_1}\&CenterDot;l---\left(4.1\right)$

Explain according to the full text of GB/T 20243/ISO 14163 and the definition of formula (4) and sound absorber formula sound suppressor side by side, have

TL＝D _s+D _a·l (4.a1)

In formula: TL – ?the sound transmission loss of sound suppressor, represent with dB; D _s– ?the discontinuous decay of sound suppressor, represent with dB; D _a– ?the transmission loss (TL) of sound suppressor, represent with dB; L – ?the length (effective length) of sound suppressor, unit is rice (m).

Therefore, length be respectively and the sound transmission loss of sound suppressor be respectively:

TL _M,1＝D _s+D _a·l ₁(4.a2)

TL _M,2＝D _s+D _a·l ₂(4.a3)

Upper two formula equations separated by connection:

$D_s=\frac{T{L}_{M,1}\&CenterDot;l_2-T{L}_{M,2}\&CenterDot;l_1}{l_2-l_1}---(4.a4)$

$D_a=\frac{T{L}_{M,2}-T{L}_{M,1}}{l_2-l_1}---(4.a5)$

Therefore have: $T{L}_M=D_s+D_a\&CenterDot;l=\frac{T{L}_{M,1}\&CenterDot;l_2-T{L}_{M,2}\&CenterDot;l_1}{l_2-l_1}+\frac{T{L}_{M,2}-T{L}_{M,1}}{l_2-l_1}\&CenterDot;l---(4.a6)$

2. the derivation of the formula of claim 5

According to fluid mechanics knowledge, in conjunction with the definition of sound absorber formula sound suppressor side by side, and with reference to the expression-form of GB/T 20243/ISO 14163 formula (10), formula (11), have

In formula: ξ _a– ?the total pressure loss coefficient of sound suppressor; D – ?the blocking area of sound suppressor section, unit is a square metre (m ²); S – ?the clean logical area of sound suppressor section, unit is a square metre (m ²); P – ?the wetted perimeter (sound absorption girth) of sound suppressor section, unit is rice (m); ξ ₁– ?sound suppressor entrance flow backwards cover resistance coefficient; ξ ₂– ?muffler outlet flow backwards cover resistance coefficient; ξ ₃– ?sound suppressor along journey coefficient of frictional resistance; L – ?the length (effective length) of sound suppressor, unit is rice (m).

For the formula of the sound absorber side by side sound suppressor of elementary cell xsect congruence, d, s, P, ξ ₁, ξ ₂, ξ ₃all identical, therefore, above formula can be reduced to:

(5.a2)

Two this cell cross-section of stylobate congruences, the sound suppressor that length does not wait, only has length not.Therefore,

In formula: ξ _{m, 1}– ?effective length be the total pressure loss coefficient of sound suppressor; ξ _{m, 2}– ?effective length be the total pressure loss coefficient of sound suppressor; K ₁– ?the coefficient of shock resistance of sound suppressor inlet/outlet; K ₂– ?the frictional resistant coefficient of sound suppressor; l ₁– ?the length (effective length) of First sound suppressor, unit is rice (m); l ₂– ?the length (effective length) of second sound suppressor, unit is rice (m).

Connection is separated above-mentioned equation and is obtained:

Thus,

3. the formula of claim 6

$L_{W,A}=L_{W,M}+10\log \left(\frac{S_A}{S_M}\right)+10\log [1+{\left(\frac{\mathrm{\&lambda;}}{2H_A}\right)}^2]-10\log [1+{\left(\frac{\mathrm{\&lambda;}}{2H_M}\right)}^2]---\left(6.1\right)$

According to GB/T 20243/ISO 14163 formula (13)

$L_W=B+10\&CenterDot;\log \{\frac{\mathrm{pcs}}{W_0}\&CenterDot;{\left(\frac{v}{c}\right)}^6\&CenterDot;[1+{\left(\frac{c}{2\mathrm{fH}}\right)}^2\left]\right\}-10\&CenterDot;\log [1+{\left(\frac{\mathrm{f\&delta;}}{v}\right)}^2]---(6.a1)$

In formula, L _wthe reproduced air-flow noise sound power level of-sound suppressor, represents with dB; The constant of B-relevant with frequency with sound suppressor type, represents with dB;

The inner Peak Flow Rate (m/s) of v-sound suppressor; C-velocity of sound (m/s); Static pressure (Pa) in p-sound suppressor; Sectional area (the m of S-Peak Flow Rate point ²);

F-frequency (Hz); The maximal side of H-sound suppressor section, unit is rice (m); δ-regenerated noise is at the characteristic parameter of high band, and unit is rice (m); W ₀-1 (watt);

For the measuring unit of elementary cell transversal section congruence and the sound suppressor of practical application, causing the affecting parameters that reproduced air-flow noise is different, is S and H, and formula (6.a1) can be converted into:

$L_W=B+10\&CenterDot;\log \{\frac{\mathrm{pc}}{W_0}\&CenterDot;{\left(\frac{v}{c}\right)}^6\&CenterDot;\}+10\&CenterDot;\log S+10\&CenterDot;\log [1+{\left(\frac{c}{2\mathrm{fH}}\right)}^2]-10\&CenterDot;\log [1+{\left(\frac{\mathrm{f\&delta;}}{v}\right)}^2]---(6.a2)$

Therefore,

$L_{W,A}=B+10\&CenterDot;\log \{\frac{\mathrm{pc}}{W_0}\&CenterDot;{\left(\frac{v}{c}\right)}^6\&CenterDot;\}+10\&CenterDot;\log S_A+10\&CenterDot;\log [1+{\left(\frac{c}{2f{H}_A}\right)}^2]-10\&CenterDot;\log [1+{\left(\frac{\mathrm{f\&delta;}}{v}\right)}^2]---(6.a3)$

$L_{W,M}=B+10\&CenterDot;\log \{\frac{\mathrm{pc}}{W_0}\&CenterDot;{\left(\frac{v}{c}\right)}^6\&CenterDot;\}+10\&CenterDot;\log S_M+10\&CenterDot;\log [1+{\left(\frac{c}{2f{H}_M}\right)}^2]-10\&CenterDot;\log [1+{\left(\frac{\mathrm{f\&delta;}}{v}\right)}^2]---(6.a4)$

Can be obtained by formula (6.a4),

$B+10\&CenterDot;\log \{\frac{\mathrm{pc}}{W_0}\&CenterDot;{\left(\frac{v}{c}\right)}^6\&CenterDot;\}-10\&CenterDot;\log [1+{\left(\frac{\mathrm{f\&delta;}}{v}\right)}^2]=L_{W,M}-10\&CenterDot;\log S_M-10\&CenterDot;\log [1+{\left(\frac{c}{2f{H}_M}\right)}^2]---(6.a5)$

Wushu (6.a5) substitutes into formula (6.a3) and obtains,

$L_{W,A}=L_{W,M}-10\&CenterDot;\log S_M-10\&CenterDot;\log [1+{\left(\frac{c}{2f{H}_M}\right)}^2]+10\&CenterDot;\log S_A+10\&CenterDot;\log [1+{\left(\frac{c}{2f{H}_A}\right)}^2]---(6.a6)$

I.e. formula (6.1): $L_{W,A}=L_{W,A}+10\log \left(\frac{S_A}{S_M}\right)+10\log [1+{\left(\frac{\mathrm{\&lambda;}}{2H_A}\right)}^2]-10\log [1+{\left(\frac{\mathrm{\&lambda;}}{2H_M}\right)}^2]$

In formula, for wavelength, unit: rice (m).

4. the derivation of equation of claim 7

$T{L}_A=T{L}_{M,S1}+\frac{T{L}_{M,S1}-T{L}_{M,S2}}{S_1-S_2}\&CenterDot;(S-S_1);$ When meeting ₁< S < S ₂, time; (7.1)

According to GB/T 20243/ISO 14163 formula (4) and formula (7)

TL＝D _s+D _a·l (7.a1)

$D_a\&Proportional;\frac{1}{s}---(7.a2)$

According to the structure of sound absorber formula sound suppressor definition side by side, its discontinuous decay D _smust be smooth continuous print with the variation relation curve of net inflow area S, therefore, when S consecutive variations, TL be also continuous print change, that is: TL can lead continuously for S.When the formula of the sound absorber side by side sound suppressor that three structures are identical, its net inflow area has following relation,

S ₁< S < S ₂, and work as S ₁infinite approach S ₂time, S ₁≈ S ≈ S ₂, TL _s1≈ TL _s≈ TL _s2, therefore, work as S ₁with S ₂the enough little or ratio of difference enough close to 1 time, can linear interpolation be used:

substitute true value TL _s, as shown in Figure 9,

5. the derivation of equation of claim 8

$T{L}_A=T{L}_{M,S1}+\frac{T{L}_{M,S1}-T{L}_{M,S2}}{S_1-S_2}\&CenterDot;(S-S_1);$ When meeting S ₁< S < S ₂, time; (8.1)

With claim 7

6. the formula of claim 9

$L_{W,M,S}=L_{W,M,S_1}-\frac{L_{W,M,S_1}-L_{W,M,S_2}}{{\log }_{10}{S}_2-{\log }_{10}{S}_1}\&CenterDot;({\log }_{10}S-{\log }_{10}{S}_1)$ When meeting S ₁< S < S ₂, time; (9.1)

$L_{W,A}=L_{W,M,S}+10\&CenterDot;{\log }_{10}N=L_{W,M,S_1}-\frac{L_{W,M,S_1}-L_{W,M,S_2}}{{\log }_{10}{S}_2-{\log }_{10}{S}_1}\&CenterDot;({\log }_{10}S-{\log }_{10}{S}_1)+10.{\log }_{10}N---\left(9.2\right)$

According to GB/T 20243/ISO 14163 formula (13)

$L_W=B+10\&CenterDot;\log \{\frac{\mathrm{pcs}}{W_0}\&CenterDot;{\left(\frac{v}{c}\right)}^6\&CenterDot;[1+{\left(\frac{c}{2fH}\right)}^2\left]\right\}-10\&CenterDot;\log [1+{\left(\frac{\mathrm{f\&delta;}}{v}\right)}^2]---(9.a1)$

In formula,

L _wthe reproduced air-flow noise sound power level of-sound suppressor, represents with dB;

The constant of B-relevant with frequency with sound suppressor type, represents with dB;

The inner Peak Flow Rate (m/s) of v-sound suppressor;

C-velocity of sound (m/s);

Static pressure (Pa) in p-sound suppressor;

Sectional area (the m of S-Peak Flow Rate point ²);

F-frequency (Hz);

The maximal side of H-sound suppressor section, unit is rice (m);

δ-regenerated noise is at the characteristic parameter of high band, and unit is rice (m);

W ₀-1 (watt);

When flow is constant,

$L_{W,s1}=B+10\&CenterDot;\log \{\frac{{\mathrm{pcs}}_1}{W_0}\&CenterDot;{\left(\frac{Q}{c\&CenterDot;S_1}\right)}^6\&CenterDot;[1+{\left(\frac{c}{2\mathrm{fH}}\right)}^2\left]\right\}-10\&CenterDot;\log [1+{\left(\frac{S_1\&CenterDot;\mathrm{f\&delta;}}{Q}\right)}^2]---(9.a2)$

$L_{W,s1}=B+10\&CenterDot;\log \{\frac{\mathrm{pc}}{W_0}\&CenterDot;{\left(\frac{Q}{c}\right)}^6\&CenterDot;[1+{\left(\frac{c}{2\mathrm{fH}}\right)}^2\left]\right\}-10\&CenterDot;\log [1+{\left(\frac{S_1\&CenterDot;\mathrm{f\&delta;}}{Q}\right)}^2]-50\&CenterDot;\log S_1---(9.a3)$

$L_{W,s2}=B+10\&CenterDot;\log \{\frac{\mathrm{pc}}{W_0}\&CenterDot;{\left(\frac{Q}{c}\right)}^6\&CenterDot;[1+{\left(\frac{c}{2\mathrm{fH}}\right)}^2\left]\right\}-10\&CenterDot;\log [1+{\left(\frac{S_2\&CenterDot;\mathrm{f\&delta;}}{Q}\right)}^2]-50\&CenterDot;\log S_2---(9.a4)$

$L_{W,s1}-L_{W,s2}=10\&CenterDot;\log \frac{[1+{\left(\frac{s_2\&CenterDot;\mathrm{f\&delta;}}{Q}\right)}^2]}{[1+{\left(\frac{s_1\&CenterDot;\mathrm{f\&delta;}}{Q}\right)}^2]}+50\&CenterDot;\log \frac{s_2}{s_1}\&le;70\&CenterDot;\log \frac{s_2}{s_1}---(9.a5)$

From above formula, pneumatic noise L _{w, s}for aisle spare S change and to change be smooth continuous print, similar with the derivation of the formula (7.1) in claim 7, based on identical reason, true value can be substituted with linear interpolation, with reference to figure 9, that is:

$L_{W,S}=L_{{W,S}_1}-\frac{L_{{W,S}_1}-L_{{W,S}_2}}{{\log }_{10}{S}_2-{\log }_{10}{S}_1}\&CenterDot;({\log }_{10}S-{\log }_{10}{S}_1),$

When time;

$L_{W,s1}-L_{W,s2}=10\&CenterDot;\log \frac{[1+{\left(\frac{s_2\&CenterDot;\mathrm{f\&delta;}}{Q}\right)}^2]}{[1+{\left(\frac{s_1\&CenterDot;\mathrm{f\&delta;}}{Q}\right)}^2]}+50\&CenterDot;\log \frac{s_2}{s_1}\&le;70\&CenterDot;\log \frac{s_2}{s_1}\&le;3\mathrm{dB};$

As the N times of the elementary cell quantity that the elementary cell quantity that the sound suppressor of practical application comprises comprises for measuring unit, no matter its section total area or the net inflow total area, is the N of the corresponding area of measuring unit doubly.Therefore, when cross-sectional flow (face velocity) is identical,

$L_{W,A}=L_{W,M,S}+10\&CenterDot;{\log }_{10}N=L_{{W,M,S}_1}-\frac{L_{{W,M,S}_1}-L_{{W,M,S}_2}}{{\log }_{10}{S}_2-{\log }_{10}{S}_1}\&CenterDot;({\log }_{10}S-{\log }_{10}{S}_1)+10\&CenterDot;{\log }_{10}N---\left(9.2\right)$

7. the derivation of equation of claim 10

Or,

According to GB/T 20243/ISO 14163 formula (10), (11), (12)

ξ＝ξ _s+ξ _f(10.a1)

${\mathrm{\&xi;}}_s={\left(\frac{d}{s}\right)}^2\&CenterDot;[0.5\&CenterDot;{\mathrm{\&xi;}}_1\&CenterDot;(\frac{s}{d}+1)+{\mathrm{\&xi;}}_2]---(10.a2)$

That is:

In formula,

ξ _sthe coefficient of shock resistance that-sound suppressor inlet/outlet is total;

ξ _f-sound suppressor frictional resistant coefficient;

ξ ₁-sound suppressor inlet end coefficient of shock resistance;

ξ ₂-muffler outlet end coefficient of shock resistance;

The blocking area of d-sound suppressor section, square metre (m ²);

The circulation area of s-sound suppressor section, square metre (m ²);

ξ ₃the coefficient of frictional resistance of-sound suppressor;

The effective length of l-sound suppressor, unit is rice (m);

When there being 4 measuring units, net inflow area ratio r is respectively: p/p/q/q, and sound absorption segment length l is respectively: l ₁/ l ₂/ l ₁/ l ₂, measuring unit enter laboratory measurement to and obtain its total pressure loss coefficient and be respectively: ξ _{m, p, 1}/ ξ _{m, p, 2}/ ξ _{m, q, 1}/ ξ _{m, q, 2}.Because the sound absorber section of 4 measuring units is identical, d is constant.Meanwhile,

$r=\frac{s}{s+d};$ rs+rd＝s； $s=\frac{\mathrm{rd}}{1-r};\frac{d}{s}=\frac{1-r}{r};\frac{s}{d}+1=\frac{r}{1-r}+1=\frac{1}{1-r};1+\frac{d}{s}=\frac{1}{r};$

And entrance point kuppe, endpiece kuppe are identical with sound absorption section surface, so, the ξ of 4 test cells ₁, ξ ₂, ξ ₃identical, formula (10.a2) is transformed to:

${\mathrm{\&xi;}}_s={\left(\frac{1-r}{r}\right)}^2\&CenterDot;[0.5\&CenterDot;{\mathrm{\&xi;}}_1\&CenterDot;(\frac{r}{1-r}+1)+{\mathrm{\&xi;}}_2]={\left(\frac{1-r}{r}\right)}^2\&CenterDot;[0.5\&CenterDot;{\mathrm{\&xi;}}_1\&CenterDot;\left(\frac{1}{1-r}\right)+{\mathrm{\&xi;}}_2]---(10.a4)$

Formula (10.a3) is transformed to:

Therefore,

Connection separates wherein 3 of above-mentioned 4 equations, can obtain,

Or,

Therefore,

Or,

Claims (10)

1., to the method that sound absorber formula sound suppressor acoustical behavior is side by side measured, comprise the method for after entering Routine Test Lab, sound suppressor being carried out to conventionally test, it is characterized in that: further comprising the steps of:

1) before entering Routine Test Lab, determine the elementary cell of the sound suppressor to be measured in practical application, this elementary cell is: when keeping this sound suppressor length constant, along its transversal section by n row × m be about to this sound suppressor simulation be divided into several elementary cells, quantity and the residing position of the transverse shape of each elementary cell, size and contained sound absorber are identical, and described n, m are positive integer;

2) measuring unit that the entered Routine Test Lab corresponding with this sound suppressor carries out measuring is set, this measuring unit is: with described elementary cell for radix by i capable × j row superposition composition, the cross-sectional dimension of this measuring unit is the size that Routine Test Lab measurement mechanism allows to enter, and described i, j are positive integer;

3) when the length of sound suppressor to be measured exceed that Routine Test Lab measurement mechanism limits upper in limited time, be the measuring unit that two length is different by the described measuring unit simulating cut corresponding from this sound suppressor to be measured, be respectively the first length measurement unit and the second length measurement unit, wherein, the length of the first length measurement unit is L ₁, the length of the second length measurement unit is L ₂, be respectively:

First length measurement unit L ₁=l _i+ l ₁+ l _o;

Second length measurement unit L ₂=l _i+ l ₂+ l _o;

l ₂≥2×l ₁；l ₁≥500mm；

L ₂the maximum measurement length that < Routine Test Lab measurement mechanism allows; l _iand l _obe respectively the contained air intake of sound absorber and the length of outlet air end in this sound suppressor elementary cell to be measured;

4) according to the method for described conventionally test to described first length measurement unit L ₁with the second length measurement unit L ₂carry out the test of sound transmission loss, pneumatic noise sound power level and total pressure loss coefficient.

2. method according to claim 1, is characterized in that: to be this measuring unit cross-sectional dimension be the elementary cell quantity contained in described measuring unit can enter quantity corresponding to elementary cell number contained when Routine Test Lab carries out the higher limit measured.

3. method according to claim 2, is characterized in that: the elementary cell that the elementary cell of described sound suppressor to be measured and measuring unit comprise is elementary cell transversal section congruence relation.

4. method according to claim 3, is characterized in that: the sound transmission loss TL obtaining described sound suppressor to be measured according to following formula _a:

TL _AL＝(TL _M1*l ₂－TL _M2*l ₁)/(l ₂－l ₁)+(TL _M2－TL _M1)*l/(l ₂－l ₁)；

TL _m1it is the sound transmission loss of the first length measurement unit;

TL _m2it is the sound transmission loss of the second length measurement unit;

L is the physical length of sound absorber sound absorption section in sound suppressor to be measured.

5. method according to claim 3, is characterized in that: the total pressure loss coefficient ξ obtaining described sound suppressor to be measured according to following formula _a:

ξ _A＝ξ _M,1－(ξ _M,2－ξ _M,1) _*l ₁/(l ₂－l ₁)+(ξ _M,2－ξ _M,1) _*l/(l ₂－l ₁)

ξ _{m, 1}be the first length measurement unit L ₁total pressure loss coefficient;

ξ _{m, 2}be the second length measurement unit L ₂total pressure loss coefficient.

6. method according to claim 3, is characterized in that: the pneumatic noise sound power level L of the sound suppressor to be measured described in obtaining according to following formula _w,A:

L _W,A＝L _W,M+10log(S _A/S _M)+10log[1+(λ/2H _A)]-10log[1+(λ/2H _M)]

L _w,M: the pneumatic noise sound power level of measuring unit, represents with dB;

S _a: the front face area of sound suppressor to be measured, unit: m ²;

S _m: the front face area of measuring unit, unit: m ²;

H _a: large limit, the transversal section size of sound suppressor to be measured, unit: m;

H _m: large limit, the transversal section size of measuring unit, unit: m;

λ: the wavelength of noise, unit: m.

7. method according to claim 2, is characterized in that: the elementary cell comprised when elementary cell and four similarity measure unit having entered Routine Test Lab of described sound suppressor to be measured has following relation:

1) be elementary cell transversal section similarity relation;

2) the net inflow area S of the elementary cell of sound suppressor to be measured contained elementary cell in four similarity measure unit is minimum net inflow area S ₁be maximum net inflow area S with elementary cell contained in four similarity measure unit ₂between;

3) and have S ₁< S < S ₂; 0.90≤S ₁/ S ₂during < 1.0;

4) elementary cell that four similarity measure unit comprise has following relation:

A. first similarity measure unit and second similarity measure unit are elementary cell transversal section congruence relation, i.e. elementary cell net inflow area equation therebetween and be described minimum net inflow area S ₁;

B. the 3rd similarity measure unit and the 4th similarity measure unit are elementary cell transversal section congruence relation, i.e. elementary cell net inflow area equation therebetween and be described maximum net inflow area S ₂;

C. first similarity measure unit and the 3rd similarity measure unit are elementary cell transversal section similarity relation and are all the first described length measurement unit, and namely these two similarity measure element lengths are identical;

D. second similarity measure unit and the 4th similarity measure unit are elementary cell transversal section similarity relation and are the second described length measurement unit, and namely these two similarity measure element lengths are identical;

Obtain the sound transmission loss TL of described sound suppressor to be measured in accordance with the following methods _a:

TL _A＝TL _M,S1+(TL _M,S1－TL _M,S2)*(S－S ₁)/(S ₁－S ₂)

TL _M,S1＝(TL _M,L1,S1*l ₂－TL _M,L2,S1*l ₁)/(l ₂－l ₁)+(TL _M,L2,S1－TL _M,L1,S1)*l/(l ₂－l ₁)；

TL _M,S2＝(TL _M,L1,S2*l ₂－TL _M,L2,S2*l ₁)/(l ₂－l ₁)+(TL _M,L2,S2－TL _M,L1,S2)*l/(l ₂－l ₁)；

TL _{m, S1}: for net inflow area is S ₁, sound absorption length is the sound transmission loss of the sound suppressor of l, represents with dB;

TL _{m, S2}: for net inflow area is S ₂, sound absorption length is the sound transmission loss of the sound suppressor of l, represents with dB;

TL _{m, L1, S1}: for first-phase is like the sound transmission loss of measuring unit, represent with dB;

TL _{m, L2, S1}: for second-phase is like the sound transmission loss of measuring unit, represent with dB;

TL _{m, L1, S2}: for third phase is like the sound transmission loss of measuring unit, represent with dB;

TL _{m, L2, S2}: the sound transmission loss being the 4th similarity measure unit, represents with dB;

TL _a: the sound transmission loss of sound suppressor to be measured, represents with dB;

S: be the net inflow area of the elementary cell of sound suppressor to be measured, unit: m ²;

S ₁: for first-phase is like measuring unit and the second-phase net inflow area like elementary cell corresponding to measuring unit, unit: m ²;

S ₂: for third phase is like the net inflow area of measuring unit and elementary cell corresponding to the 4th similarity measure unit, unit: m ²;

L: be the physical length of sound suppressor sound absorption section to be measured;

L ₁: for first-phase is like measuring unit and the third phase length like measuring unit sound absorption section;

L ₂: for second-phase like measuring unit and the 4th similarity measure unit sound absorption section length.

8. method according to claim 2, is characterized in that: when sound suppressor length L to be measured is the length that can enter Routine Test Lab, arranges in the following manner:

1) getting with sound suppressor to be measured is the 5th similarity measure unit and the 6th similarity measure unit of elementary cell transversal section similarity relation;

2) the net inflow area S of the net inflow area S of the elementary cell of sound suppressor to be measured elementary cell contained by the 5th similarity measure unit ₁with the net inflow area S of elementary cell contained in the 6th similarity measure unit ₂between;

3) and have S ₁< S < S ₂; 0.90≤S ₁/ S ₂during < 1.0;

4) length of the 5th similarity measure unit is identical with sound suppressor length to be measured;

5) length of the 6th similarity measure unit is identical with sound suppressor length to be measured;

Obtain the sound transmission loss TL of described sound suppressor to be measured in accordance with the following methods _a:

TL _A＝TL _M,S1+(TL _M,S1－TL _M,S2)*(S－S ₁)/(S ₁－S ₂)

TL _{m, S1}: the sound transmission loss being the 5th similarity measure unit, represents with dB;

TL _{m, S2}: the sound transmission loss being the 6th similarity measure unit, represents with dB;

TL _a: be the sound transmission loss of sound suppressor to be measured, represent with dB;

S: be the net inflow area of the elementary cell of sound suppressor to be measured, unit: m ²;

S ₁: the net inflow area being the elementary cell of the 5th similarity measure unit, unit: m ²;

S ₂: the net inflow area being the elementary cell of the 6th similarity measure unit, unit: m ²;

L: be the physical length of sound suppressor sound absorption section to be measured.

9. method according to claim 2, is characterized in that: the elementary cell comprised when elementary cell and two similarity measure unit having entered Routine Test Lab of described sound suppressor to be measured has following relation:

1) be elementary cell transversal section similarity relation;

2) the net inflow area S of the elementary cell of sound suppressor to be measured is between the net inflow area S of first-phase like elementary cell contained by measuring unit ₁with the net inflow area S of second-phase like elementary cell contained in measuring unit ₂between;

3) and have S ₁< S < S ₂; 0.90≤S ₁/ S ₂during < 1.0;

Obtain the pneumatic noise sound power level L of described sound suppressor to be measured in accordance with the following methods _{w, A:}

L _W,A＝L _W.M.S+10log ₁₀N＝L _W,M,S1-(L _W,M,S1-L _W,M,S2)*(log ₁₀S-log ₁₀S ₁)/(log ₁₀S ₂-log ₁₀S ₁)+10log ₁₀N

L _w,A: be the pneumatic noise sound power level of sound suppressor to be measured, represent with dB;

L _{w, M, S1}: be the pneumatic noise sound power level of E measuring unit, represent with dB;

L _{w, M, S2}: be the pneumatic noise sound power level of F measuring unit, represent with dB;

N: the ratio of elementary cell that sound suppressor to be measured comprises sum and the number of elementary cell contained by described test cell;

S: the net inflow area of the elementary cell of sound suppressor to be measured, unit: m ²;

S ₁: for first-phase is like the net inflow area of the elementary cell contained by measuring unit, unit: m ²;

S ₂: for second-phase is like the net inflow area of the elementary cell contained by measuring unit, unit: m ².

10. method according to claim 2, is characterized in that: the elementary cell comprised when elementary cell and four similarity measure unit having entered Routine Test Lab of described sound suppressor to be measured has following relation:

1) be elementary cell transversal section similarity relation;

2) the net inflow area S of the elementary cell of sound suppressor to be measured contained elementary cell in four similarity measure unit is minimum net inflow area S ₁be maximum net inflow area S with elementary cell contained in four similarity measure unit ₂between;

3) S ₁< S < S ₂; 0.90≤S ₁/ S ₂during < 1.0;

4) elementary cell that four similarity measure unit comprise has following relation:

A. first similarity measure unit and second similarity measure unit are elementary cell transversal section congruence relation, i.e. elementary cell net inflow area equation therebetween and be described minimum net inflow area S ₁;

B. the 3rd similarity measure unit and the 4th similarity measure unit are elementary cell transversal section congruence relation, i.e. elementary cell net inflow area equation therebetween and be described maximum net inflow area S ₂;

C. first similarity measure unit and the 3rd similarity measure unit are elementary cell transversal section similarity relation and are all the first described length measurement unit, and namely these two similarity measure element lengths are identical;

D. second similarity measure unit and the 4th similarity measure unit are elementary cell transversal section similarity relation and are the second described length measurement unit, and namely these two similarity measure element lengths are identical;

Obtain the total pressure loss coefficient ξ of described sound suppressor to be measured in accordance with the following methods _{a, r, l:}

ξ _A,r,l＝(1-r/r) ²*{(ξ _M,p,1*l ₂-ξ _M,p,2*l ₁)p ²*[(r-q)/(1-r)]/[(1-p)*(1-q)-(1-p) ²]+

+(ξ _M,q,1*l ₂-ξ _M,q,2*l ₁)q ²*[(r-p)/(1-r)]/[(1-p)*(1-q)-(1-q) ²]}/(l ₂-l ₁)+

+(ξ _M,p,2-ξ _M,p,1)*p ³(1-r)*l/r ³(1-p)*(l ₂-l ₁)

Or,

ξ _A,r,l＝(1-r/r) ²*{(ξ _M,p,1*l ₂-ξ _M,p,2*l ₁)p ²*[(r-q)/(1-r)]/[(1-p)*(1-q)-(1-p) ²]+

+(ξ _M,q,1*l ₂-ξ _M,q,2*l ₁)q ²*[(r-p)/(1-r)]/[(1-p)*(1-q)-(1-q) ²]}/(l ₂-l ₁)+

+(ξ _M,q,2-ξ _M,q,1)*q ³(1-r)*l/r ³(1-p)*(l ₂-l ₁)

ξ _{m, p, 1:}for first-phase is like the total pressure loss coefficient of measuring unit;

ξ _{m, p, 2:}for second-phase is like the total pressure loss coefficient of measuring unit;

ξ _{m, q, 1:}for third phase is like the total pressure loss coefficient of measuring unit;

ξ _{m, q, 2:}it is the total pressure loss coefficient of the 4th similarity measure unit;

P: be the net inflow area ratio of first and second similarity measure unit; P=S ₁/ (S ₁+ S ₀);

Q: be the net inflow area ratio of third and fourth similarity measure unit; Q=S ₂/ (S ₂+ S ₀)

R: be the net inflow area ratio of sound suppressor to be measured; R=S/ (S+S ₀)

S: be the net inflow area of the elementary cell of sound suppressor to be measured, unit: m ²;

S ₁: the net inflow area of the elementary cell contained by first and second similarity measure unit, unit: m ²;

S ₂: the net inflow area of the elementary cell contained by third and fourth similarity measure unit, unit: m ²;

S ₀: the elementary cell blocking area separately contained by four similarity measure unit and sound suppressor to be measured, unit: m ²; ;

L: be the physical length of sound suppressor sound absorption section to be measured;

L ₁: the length being first and third similarity measure unit sound absorption section;

L ₂: the length being second, four similarity measure unit sound absorption sections.