# BS ISO 15086-1-2001

BRITISH STANDARD BS ISO 15086-1:2001 Hydraulic fluid power — Determination of the fluid-borne noise characteristics of components and systems — Part 1: Introduction ICS 17.140.20; 23.100.01; NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBS ISO 15086-1:2001 This British Standard, having been prepared under the direction of the Engineering Sector Policy and Strategy Committee, was published under the authority of the Standards Policy and Strategy Committee and comes into effect on 23 October 2001 © BSI 23 October 2001 ISBN 0 580 37357 6 National foreword This British Standard reproduces verbatim ISO 15086-1:2001 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee MCE/18, Fluid power systems and components, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. — aid enquirers to understand the text; — present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; — monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover,ISO title page, pages ii to v, a blank page, pages 1 to 11 and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments Reference number ISO 15086-1:2001(E)INTERNATIONAL STANDARD ISO 15086-1 First edition 2001-10-01 Hydraulic fluid power — Determination of fluid-borne noise characteristics of components and systems — Part 1: Introduction Transmissions hydrauliques — Évaluation des caractéristiques du bruit liquidien des composants et systèmes — Partie 1: Introduction ISO 15086-1:2001(E) lcsid FDParemi ihTs PDF file mac ytnoaie nmt deddebyfepca.se In ccaocnadrw eith A ebods licsneilop gnic,y this file mairp eb yntiv ro deewb detu slahl ton ide ebtlnu desse tt ehyfepacse whice era hml era deddebicsnede to i dnanstlaled t noeh comtupfrep reomrign tide ehti.gn In wodnlidaogn this file, trapies ccatpe tiereht nsnopser ehibility fo ton infriignA gnd ebos licnesilop gnic.y I ehTStneC Oarl Secrteiraat cacepts l oniibality in this .aera Ai ebods a tredamafo kr Aebod SystemI sncotaropr.de teDails fo ts ehoftwaorp ercudts ust deo crtaet ehis PDF file ceb na fi dnuon tlareneG eh Info leratit evo tf ehile; tP ehD-Fcrtaeiarap nomtesre were tpoimizf deoirp rnti.gn Evyre casah er t neebakt neo snet eruhat tf ehile is suitlbaf eosu rI yb eSO memidob rebse. In the lnuikletneve y ttah alborp emler ati gnto it is fnuo,dlp saee inform ttneC ehlar Secrteiraat at tsserdda ehig leb nevwo. ii ISO 15086-1:2001(E) iiiContents Page Foreword.iv Introduction.v 1 Scope1 2 Normative reference1 3 Terms and definitions .1 4 Symbols3 5 Basic considerations.3 6 Practical aspects.7 Bibliography11 ISO 15086-1:2001(E) iv Foreword ISO (the International Organization for Standardization) 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 represented 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 are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this part of ISO 15086 may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. International Standard ISO 15086-1 was prepared by Technical Committee ISO/TC 131, Fluid power systems, Subcommittee SC 8, Product testing. ISO 15086 consists of the following parts, under the general title Hydraulic fluid power — Determination of fluid- borne noise characteristics of components and systems: — Part 1: Introduction — Part 2: Measurement of the speed of sound in a fluid in a pipe ISO 15086-1:2001(E) vIntroduction The airborne noise emitted by hydraulically actuated equipment is the result of simultaneous acoustic radiation from all mechanical structures comprising the machine. The contribution from individual components generally forms only a small part of the total acoustic energy radiated. Acoustic intensity measurement techniques have demonstrated that the pulsating energy in the hydraulic fluid (fluid-borne noise) is the dominant contributor to machine noise. In order to develop quieter hydraulic machines it is therefore necessary to reduce this hydro- acoustic energy. Various approaches have been developed to describe the generation and transmission of fluid-borne noise in hydraulic systems. Of these, the transfer matrix approach has the merit of providing a good description of the physical behaviour as well as providing an appropriate basis for the measurement of component characteristics. INTERNATIONAL STANDARD ISO 15086-1:2001(E)1Hydraulic fluid power — Determination of fluid-borne noise characteristics of components and systems — Part 1: Introduction 1 Scope This part of ISO 15086 provides a general introduction to transfer matrix theory, which allows the determination of the fluid-borne noise characteristics of components and systems. It also provides guidance on practical aspects of fluid-borne noise characterization. This part of ISO 15086 is applicable to all types of hydraulic fluid power circuits operating under steady-state conditions for fluid-borne noise over an appropriate range of frequencies. 2 Normative reference The following normative document contains provisions which, through reference in this text, constitute provisions of this part of ISO 15086. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of ISO 15086 are encouraged to investigate the possibility of applying the most recent editions of the normative document indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 5598, Fluid power systems and components — Vocabulary 3 Terms and definitions For the purposes of this part of ISO 15086, the terms and definitions given in ISO 5598 and the following apply. 3.1 flow ripple fluctuating component of flow rate in a hydraulic fluid, caused by interaction with a flow ripple source within the system 3.2 pressure ripple fluctuating component of pressure in a hydraulic fluid, caused by interaction with a flow ripple source within the system 3.3 hydraulic noise generator hydraulic component generating flow ripple and consequently pressure ripple in a circuit, or hydraulic component generating pressure ripple and consequently flow ripple in the circuit ISO 15086-1:2001(E) 2 3.4 fundamental frequency lowest frequency of pressure (or flow) ripple considered in a theoretical analysis or measured by the frequency- analysis instrument EXAMPLE 1 A hydraulic pump or motor with a shaft frequency of N revolutions per second may be taken to have a fundamental frequency of N Hz. Alternatively, for a pump or motor with k displacement elements, the fundamental frequency may be taken to be Nk Hz, provided that the measured behaviour does not deviate significantly from cycle to cycle. EXAMPLE 2 A digital frequency analyzer has a fundamental frequency defined by the frequency of the first spectral line. 3.5 harmonic sinusoidal component of the pressure ripple or flow ripple occurring at an integer multiple of the fundamental frequency. NOTE A harmonic may be represented by its amplitude and phase or alternatively by its real or imaginary parts. 3.6 impedance complex ratio of the pressure ripple to the flow ripple occurring at a given point in a hydraulic system and at a given frequency NOTE Impedance may be expressed in terms of its amplitude and phase or alternatively by its real and imaginary parts. 3.7 admittance reciprocal of impedance 3.8 characteristic impedance of a pipeline impedance of an infinitely long pipeline of constant cross-sectional area 3.9 wavelength ratio of the speed of sound to the frequency of interest (in hertz) 3.10 anechoic without reflection NOTE With reference to a condition in which a travelling wave is propagated but no energy is reflected back in the direction of propagation. 3.11 hydro-acoustic energy fluctuating part of the energy in a liquid 3.12 broad-band fluid-borne noise hydro-acoustic energy distributed over the frequency spectrum 3.13 port-to-port symmetry property of a two-port component in which the wave propagation characteristics remain the same when its port connections to the circuit are reversed ISO 15086-1:2001(E) 34 Symbols The following symbols are used in this part of ISO 15086. A, A¢, A* Complex coefficient B, B¢, B* Complex coefficient C¢ Complex coefficient c Acoustic velocity d Internal diameter of pipe f Frequency (hertz) f 0Fundamental frequency (hertz) j Complex operator L Distance along pipe n Total number of harmonics P Fourier transform of pressure ripple p(t) Time-dependent pressure ripple p iAmplitude of i-th harmonic of pressure ripple Q Fourier transform of flow ripple q(t) Time-dependent flow ripple q iAmplitude of i-th harmonic of flow ripple R Magnitude of harmonic component (pressure or flow ripple, as appropriate) t Time e fError in calculation of flow ripple at junction j iPhase of i-th harmonic of pressure ripple n Kinematic viscosity q Phase of harmonic component (pressure or flow ripple, as appropriate) w Frequency (rads per second) y iPhase of i-th harmonic of flow ripple 5 Basic considerations 5.1 General The time-dependent pressure and flow ripples in a hydraulic system can be described mathematically by a Fourier series. Figure 1 shows, as an example, a periodic flow ripple signal in the time domain, while Figure 2 shows the corresponding frequency domain representation. The phase can lie in the range -180° to 180°. The spectra shown in Figure 2 present the harmonic components in terms of their amplitude and phase. It is also possible to present these components in terms of their real and imaginary parts. Frequency domain representations are readily obtained using frequency analysis instrumentation. For the determination of the fluid-borne noise characteristics of hydraulic components and systems, only periodic signals are considered. ISO 15086-1:2001(E) 4 5.2 Frequency spectrum representation of pressure ripple The time-dependent pressure ripple p(t) is closely approximated by a finite sum of pure sinusoidal pressure ripples, p i (t). Each sinusoidal component is described by its amplitude (p i ) and phase (j i ). () ( ) 1 0 sin 2 + n ii i pt p i ft = Â = ϕ π (1) The time-dependent flow ripple q(t) is also closely approximated by a finite sum of pure sinusoidal flow ripple, q i (t). Each sinusoidal component is described by its amplitude (q i ) and phase (y i ). () ( ) 0 1 sin 2 n ii i qt q i ft y = =p + Â(2) At a particular frequency ( f ) which is an integer (m) multiple of the fundamental frequency ( f 0) (i.e. f = mf 0 ), the pressure ripple has an amplitude P mand phase j m . The corresponding flow ripple has an amplitude of Q mand a phase of y m . It is also possible to represent these harmonic components in terms of their real and imaginary parts: cos j sin RRR qqq –= + (3) 5.3 Mathematical modelling of wave propagation in a pipe in the frequency domain The mathematical modelling of plane wave propagation presented in this part of ISO 15086 takes into account fluid viscosity effects and is readily applicable to analysis in the frequency domain. This model is appropriate for all Newtonian hydraulic fluids over a wide range of mean pressures and temperatures. At each frequency, the flow ripple at one location (i) in a pipe is represented by a linear combination of the pressure ripple at that location and one other location ( j ). In complex number notation: ij QA P B P ij =+ Æ(4) Figure 1 — Example of time domain waveform ISO 15086-1:2001(E) 5a) Amplitude spectrum b) Phase spectrum Figure 2 — Frequency spectra corresponding to Figure 1 ISO 15086-1:2001(E) 6 The volumetric flow pulsation Q iÆjis positive for flows from i to j. The complex numbers A and B are functions of frequency and depend on the geometric characteristics of the pipe and the characteristics of the fluid. With the effects of fluid viscosity at the pipe wall taken into account, a and b are closely approximated by: [] () 4 2 2 coth d ωL A ja j b aj b ρc =- - π(5) π 4 2 2 sin( ) d ωLj B aj b aj b ρc = --(6) 2 2 L ων a ω c d Êˆ =+ Á˜ Ë¯(7) 22 42 L νω ν b c dd Êˆ =+ Á˜ Ë¯(8) The parameters a and b are calculated with sufficient accuracy provided: 4 2 ν ω d For example, n = 50 ¥ 10 -6m 2 /s (50 cSt) and d = 0,01 m. For the theory to be valid w has to be much greater than 2 rad/s. This is the case for all hydraulic fluid power systems. Because a pipeline of constant cross-sectional area has physical symmetry, the flow ripple at section ( j) can be expressed by: ji j i QA PB P Æ =+ (9) The complex numbers A and B are identical to the numbers in Equation 4. 5.4 Continuity equation At the connecting point between two or more pipes, or between a pipe and a component, the algebraic sum of the flow equates to zero. One consequence of this is that a single pipe can be subdivided into two separate pipes of the same cross- sectional area. The pressure ripple at the junction can then be expressed as a function of the pressure ripple at one location upstream of the junction and one location downstream of the junction. Consider the following: 21 2 1 QA PB P Æ =+ (10) 23 2 3 QA PB P Æ =+ (11) A¢ and B¢ will differ from A and B if the dist