1、 Reference number ISO/TS 7849-2:2009(E) ISO 2009TECHNICAL SPECIFICATION ISO/TS 7849-2 First edition 2009-03-15 Acoustics Determination of airborne sound power levels emitted by machinery using vibration measurement Part 2: Engineering method including determination of the adequate radiation factor A
2、coustique Dtermination des niveaux de puissance acoustique ariens mis par les machines par mesurage des vibrations Partie 2: Mthode dexpertise incluant la dtermination dun facteur de rayonnement appropri ISO/TS 7849-2:2009(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance
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7、ase postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2009 All rights reservedISO/TS 7849-2:2009(E) ISO 2009 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative refere
8、nces . 1 3 Terms and definitions. 2 4 Principle. 4 5 Measuring instrumentation 5 5.1 General. 5 5.2 Vibration transducer. 5 5.3 Non-contacting transducers 6 5.4 Amplifier and filter 6 5.5 Integrator . 6 5.6 Calibration . 6 6 Installation and operation of source under test 7 6.1 General. 7 6.2 Descri
9、ption of the machine 7 6.3 Installation . 7 6.4 Operating conditions 7 7 Determination of the vibratory velocity on the vibrating measurement surface . 7 7.1 General. 7 7.2 Vibrating measurement surface 8 7.3 Number of measurement positions 8 7.4 Environmental conditions 9 7.5 Measurement procedure
10、9 7.6 Mounting of the vibration transducer. 9 8 Determination of the machinery specific frequency band radiation factor 10 9 Calculations. 11 9.1 Correction for extraneous vibratory velocity. 11 9.2 Determination of the mean vibratory velocity level on the vibrating measurement surface 12 9.3 Calcul
11、ation of the airborne sound power level caused by radiation of structure vibration generated sound. 13 10 Measurement uncertainty 13 11 Information to be recorded 14 11.1 Machine under test . 14 11.2 Measurement conditions . 15 11.3 Measuring instrumentation 15 11.4 Acoustical data . 15 Annex A (inf
12、ormative) Use of the vibration transducer 16 Annex B (normative) Procedures for calculating A-weighted sound power levels from octave band or one-third-octave band levels. 18 Annex C (informative) Recommendations concerning the frequency bands of interest . 20 Annex D (informative) Determination of
13、the vibratory velocity level from the vibratory acceleration level 21 Annex E (informative) Guidance on the development of information on measurement uncertainty 23 Bibliography . 26 ISO/TS 7849-2:2009(E) iv ISO 2009 All rights reservedForeword ISO (the International Organization for Standardization
14、) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be repr
15、esented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards ar
16、e drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an Internation
17、al Standard requires approval by at least 75 % of the member bodies casting a vote. In other circumstances, particularly when there is an urgent market requirement for such documents, a technical committee may decide to publish other types of document: an ISO Publicly Available Specification (ISO/PA
18、S) represents an agreement between technical experts in an ISO working group and is accepted for publication if it is approved by more than 50 % of the members of the parent committee casting a vote; an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical c
19、ommittee and is accepted for publication if it is approved by 2/3 of the members of the committee casting a vote. An ISO/PAS or ISO/TS is reviewed after three years in order to decide whether it will be confirmed for a further three years, revised to become an International Standard, or withdrawn. I
20、f the ISO/PAS or ISO/TS is confirmed, it is reviewed again after a further three years, at which time it must either be transformed into an International Standard or be withdrawn. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. IS
21、O shall not be held responsible for identifying any or all such patent rights. ISO/TS 7849-2 was prepared by Technical Committee ISO/TC 43, Acoustics, Subcommittee SC 1, Noise. This first edition of ISO/TS 7849-2, together with ISO/TS 7849-1, cancel and replace the first edition of ISO/TR 7849:1987,
22、 which has been technically revised. ISO/TS 7849 consists of the following parts, under the general title Acoustics Determination of airborne sound power levels emitted by machinery using vibration measurement: Part 1: Survey method using a fixed radiation factor Part 2: Engineering method including
23、 determination of the adequate radiation factor The following part is under preparation: Part 3: Amplitude and phase measurements ISO/TS 7849-2:2009(E) ISO 2009 All rights reserved v Introduction This part of ISO/TS 7849 gives a procedure for the determination of the sound power of the airborne nois
24、e caused by machinery vibration, including determination and application of the adequate radiation factor. The determination of airborne noise emission of a machine by measuring vibration of the machines outer surface may be of interest when: undesired background noise (e.g. noise from other machine
25、s or sound reflected by room boundaries) is high compared with the noise radiated directly by the machine under test; noise radiated by structure vibration is to be separated from noise of aerodynamic origin; noise radiated by structure vibration is high compared to the aerodynamic component so that
26、 the total noise radiation is predominantly affected by the structure vibration; sound intensity measurement techniques ISO 9614 (all parts) 14 cannot easily be applied; structure vibration generated noise from only a part of a machine, or from a component of a machine set, is to be determined in th
27、e presence of noise from the other parts of the whole source. ISO/TS 7849 (all parts) describes methods for the determination of the airborne noise emission of a machine caused by vibration of its outer surface, expressed by the associated airborne sound power being related to normalized meteorologi
28、cal conditions. This airborne sound power is determined under the assumption that this quantity is proportional to the mean square value of the normal component of the velocity averaged over the area of the vibrating outer surface of the machine, and is directly proportional to the area of the vibra
29、ting surface. The calculation of the airborne sound power needs data of the radiation factor, , as a function of frequency for the machine under test. These values can be taken as unity ( = 1) independently of frequency, yielding an upper limit for the sound power (see ISO/TS 7849-1); or, it can be
30、determined for specific machines as described in this part of ISO/TS 7849. Details of ISO/TS 7849 (all parts) are given in the foreword. TECHNICAL SPECIFICATION ISO/TS 7849-2:2009(E) ISO 2009 All rights reserved 1 Acoustics Determination of airborne sound power levels emitted by machinery using vibr
31、ation measurement Part 2: Engineering method including determination of the adequate radiation factor 1 Scope This part of ISO/TS 7849 gives basic requirements for a reproducible method for the determination of the sound power level of the noise emitted by machinery or equipment by using surface vib
32、ration measurements, together with the knowledge of the machinery specific sound radiation factor in the frequency bands. The method is only applicable to noise which is emitted by vibrating surfaces of solid structures and not to noise generated aerodynamically. This vibration measurement method is
33、 especially applicable in cases where accurate direct airborne noise measurements, e.g. as specified in ISO 3746 7 , ISO 3747 8 , and ISO 9614 (all parts) 14 , are not possible because of high background noise or other parasitic environmental interferences; or, if a distinction is required between t
34、he total radiated sound power and its structure vibration generated component. NOTE 1 One of the applications of this part of ISO/TS 7849 is the distinction between the radiation of airborne sound power generated by structure vibration and the aerodynamic sound power components. Such a distinction i
35、s not feasible with ISO 3744 5 , ISO 3745 6 , ISO 3746 7and ISO 9614 (all parts) 14 . NOTE 2 Problems may occur if the noise is generated by small parts of machinery surfaces (sliding contacts, e.g. slip ring brush or the commutator and the brush in electrical machines). The methods described in thi
36、s part of ISO/TS 7849 apply mainly to processes that are stationary with respect to time. Recommendations on the selection of frequency bands are given in Annex C. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references,
37、only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 5348, Mechanical vibration and shock Mechanical mounting of accelerometers ISO/IEC Guide 98-3:2008, Uncertainty of measurement Part 3: Guide to the expression
38、 of uncertainty in measurement (GUM:1995) IEC 61260, Electroacoustics Octave-band and fractional-octave-band filters IEC 61672-1, Electroacoustics Sound level meters Part 1: Specifications ISO/TS 7849-2:2009(E) 2 ISO 2009 All rights reserved3 Terms and definitions For the purposes of this document,
39、the following terms and definitions apply. 3.1 structure vibration generated sound airborne sound caused by structure vibration in the audible frequency range NOTE For the purposes of this part of ISO/TS 7849, structure vibration generated sound is determined either from the vibratory velocity or th
40、e vibratory acceleration of the surface of the solid structure. ISO/TS 7849-1:2009 3.2 machine airborne sound power level measurement of single item equipment which incorporates a single or several noise sources ISO/TS 7849-1:2009 3.3 vibratory velocity v root-mean square (r.m.s.) value of the compo
41、nent of the velocity of a vibrating surface in the direction normal to the surface NOTE The vibratory velocity, v, is the time integral of the vibratory acceleration, whose r.m.s. value is given for sinusoidal vibration by: 2 a v f = (1) where a is the r.m.s. acceleration; f is the frequency. The vi
42、bratory velocity, v, is the time derivative of the vibratory displacement, s, ds/dt. For sinusoidal vibration, the r.m.s. velocity, v, is given by: 2 vf s = (2) where s is the r.m.s. displacement. ISO/TS 7849-1:2009 3.4 frequency band vibratory velocity level L vjten times the logarithm to the base
43、10 of the ratio of the square of the r.m.s. value of the vibratory velocity for the jth frequency band, v j , to the square of a reference value, v 0 , expressed in decibels: 2 2 0 10 lg dB j vj v L v = (3) ISO/TS 7849-2:2009(E) ISO 2009 All rights reserved 3 where v jis the r.m.s. value of the vibr
44、atory velocity, in metres per second, for the jth frequency band1) ; v 0is the reference value for the velocity and is equal to 5 10 8m/s) 2) . NOTE For airborne and structure vibration generated sound, the reference value v 0= 5 10 8m/s (or 50 nm/s) has the property that it leads, together with p 0
45、= 2 10 5Pa, to the reference value of the intensity level I 0= 1 10 12W/m 2and to the characteristic impedance of air by p 0 /v 0= 400 N s/m 3 . 3.5 frequency band radiation factor jfactor expressing the efficiency of sound radiation given by: 2 c j j j P Z Sv = (4) where P jis the airborne sound po
46、wer in the jth frequency band, emitted by the vibrating surface of the machine, determined according to ISO 9614 (all parts) 14 ; S is the area of the defined outer surface of the machine under test (vibrating measurement surface; see 3.7); 2 j v is the squared r.m.s. value of the vibratory velocity
47、 measured for the jth frequency band and averaged over S; Z cis the characteristic impedance of air. NOTE The four quantities A , P A , 2 A v , and Z crelate to the same period of time and to the same meteorological conditions (atmospheric temperature, , and barometric pressure, B). 3.6 airborne sou
48、nd power level L Wjten times the logarithm to the base 10 of the ratio of the frequency band airborne sound power emitted by the surface of a machine, P j , to a reference value, P 0 , expressed in decibels: 0 10 lg dBj Wj P L P = (5) where the reference value, P 0 , is 10 12W. NOTE The width of a r
49、estricted frequency band is indicated, e.g. octave-band sound power level, one-third-octave-band sound power level. 1) A subscript “eff” is dropped since only r.m.s. values are used throughout this part of ISO/TS 7849. 2) In ISO 1683 1 , two reference values for the velocity level are mentioned: v 0= 10 9m/s and 5 10 8m/s (= 50 nm/s). The latter is intended for cases of airborne and structure vibration generated sound and is therefore used in thi
