1、 Guidance Notes on Ship Noise Analysis GUIDANCE NOTES ON ONBOARD SHIP NOISE ANALYSIS FEBRUARY 2018 American Bureau of Shipping Incorporated by Act of Legislature of the State of New York 1862 2018 American Bureau of Shipping. All rights reserved. ABS Plaza 16855 Northchase Drive Houston, TX 77060 US
2、A Foreword Foreword These Guidance Notes provide an overview of and specific guidance on onboard ship noise analysis methodologies. There is an increased demand for onboard ship noise analysis due to several industry requirements relating to noise exposure levels for seafarers. These include the Int
3、ernational Labour Organizations (ILO) Maritime Labour Convention (MLC), 2006 and the IMO Code on Noise, which came into force in July 2014. To support ship designers and builders in improving the acoustic design of their ships, ABS has developed these Guidance Notes and has offered noise analysis se
4、rvices for years. Included in these Guidance Notes are commonly-used modeling and analysis methods, as well as the basic concepts for the evaluation of noise analyses. These Guidance Notes can be used to assist in the noise analysis for ocean-going vessels. These Guidance Notes become effective on t
5、he first day of the month of publication. Users are advised to check periodically on the ABS website www.eagle.org to verify that this version of these Guidance Notes is the most current. We welcome your feedback. Comments or suggestions can be sent electronically by email to rsdeagle.org. Terms of
6、Use The information presented herein is intended solely to assist the reader in the methodologies and/or techniques discussed. These Guidance Notes do not and cannot replace the analysis and/or advice of a qualified professional. It is the responsibility of the reader to perform their own assessment
7、 and obtain professional advice. Information contained herein is considered to be pertinent at the time of publication, but may be invalidated as a result of subsequent legislations, regulations, standards, methods, and/or more updated information and the reader assumes full responsibility for compl
8、iance. This publication may not be copied or redistributed in part or in whole without prior written consent from ABS. ii ABSGUIDANCE NOTES ON ONBOARD SHIP NOISE ANALYSIS .2018 Table of Contents GUIDANCE NOTES ON ONBOARD SHIP NOISE ANALYSIS CONTENTS SECTION 1 General 1 1 Introduction . 1 3 Applicati
9、on 1 5 Scope 1 7 Relevant Documents . 2 9 Terminology 2 SECTION 2 Source-Path-Receiver Modeling . 4 1 Overview . 4 3 Source . 5 3.1 Overview . 5 3.3 Machinery 5 3.5 Propulsion . 7 3.7 Ventilation Fans . 9 5 Sound Transmission Path . 9 5.1 Airborne Path 10 5.3 Structure-borne Path . 11 5.5 Duct-borne
10、 Path 13 5.7 Fluid Load 14 5.9 Path Simplification . 14 7 Receiver 15 7.1 Radiation Efficiency . 15 7.3 Room Constant . 16 TABLE 1 Airborne Sound Transmission Loss of Typical Ship Panels . 11 TABLE 2 Damping Loss Factor for Typical Hull Structures . 12 TABLE 3 Damping Loss Factor for Two Types of Da
11、mping 12 TABLE 4 Radiation Efficiency of Typical Ship Structures, 10lograd15 TABLE 5 Acoustic Absorption Coefficients of Typical Materials 16 FIGURE 1 Noise Transmission Flow Chart 4 FIGURE 2 Noise Sources on Board Ships . 5 FIGURE 3 Resilient Mount and Foundation Arrangement . 7 FIGURE 4 Calculatio
12、n Procedure for Propeller Induced Vibration . 8 FIGURE 5 Sound Transmission through Compartments . 10 ABSGUIDANCE NOTES ON ONBOARD SHIP NOISE ANALYSIS .2018 iii FIGURE 6 Typical Configuration of Floating Floor . 13 FIGURE 7 Sound Transmission via HVAC Ducts 14 FIGURE 8 Type A Vessel Accommodation Ar
13、ea in Fore Part 15 FIGURE 9 Type B Vessel Accommodation Area in Aft Part . 15 SECTION 3 Results Evaluation . 17 1 Frequency Analysis and Octave Bands 17 3 A-weighting Evaluation . 17 5 Criteria . 18 5.1 ABS Criteria . 18 5.3 ILO MLC 2006 and IMO Noise Code . 18 TABLE 1 A-filter Values 18 TABLE 2 Noi
14、se Level Limits, dB(A) 19 FIGURE 1 A-Weighting Filtering Curve 18 APPENDIX 1 Empirical Method 20 1 Airborne Sound Transmission . 20 1.1 Airborne Sound Transmission in Source Room . 20 1.3 Airborne Sound Transmission Loss through a Partition . 20 1.5 Airborne Sound Transmission through Large Openings
15、 21 3 Structure-borne Sound Transmission . 21 3.1 Within the Source Room 22 3.3 Beyond Source Room 22 3.5 Intersections 23 5 Duct-borne Sound Transmission 23 5.1 Plenum 23 5.3 Silencers 23 5.5 Straight Duct Attenuation . 24 5.7 Branches . 24 5.9 Turns . 25 5.11 End Reflections at Duct Openings . 25
16、TABLE 1 Approximate Attenuation of Typical Silencers, in dB 24 TABLE 2 , Attenuation, in dB per Meter of Duct Length . 24 TABLE 3 , Attenuation, in dB per Feet of Duct Length . 24 TABLE 4 Attenuation for Turns, in dB 25 FIGURE 1 Directivity Factors Q 20 FIGURE 2 Incident Angle . 21 FIGURE 3 Source R
17、oom Layout 22 FIGURE 4 Structure-borne Sound Transmission Path in Ship Structures 23 iv ABSGUIDANCE NOTES ON ONBOARD SHIP NOISE ANALYSIS .2018 APPENDIX 2 Statistical Energy Analysis (SEA) Method . 26 1 Overview . 26 3 Energy Flow Relationships . 27 FIGURE 1 Acoustical Power Flow between Two Subsyste
18、ms . 27 APPENDIX 3 References 29 ABSGUIDANCE NOTES ON ONBOARD SHIP NOISE ANALYSIS .2018 v This Page Intentionally Left Blank Section 1: General SECTION 1 General 1 Introduction Noise on board ships has seen increased attention in recent years. Excessive noise levels on board ships can adversely affe
19、ct the task performance and health of seafarers. Seafarers may become distracted if exposed to high noise and vibration levels and this can increase the potential for human error. Prolonged exposure to high-noise environments can lead to long-term health issues such as noise-induced hearing loss. It
20、 is expensive and difficult to fix noise-related issues after construction. Therefore, it is important and necessary for ship designers and builders to perform noise analyses and address these concerns at an early design stage. ABS has offered noise analysis service for years. For onboard ship noise
21、 analyses, the commonly adopted “Source-Path-Receiver” modeling technique may be used. This modeling scheme takes three key elements into consideration: noise sources, transmission paths, and the receiver acoustic characteristics. Empirical methods and numerical analysis methods can be used to calcu
22、late the sound attenuation from “Sources” to “Receivers” through different transmission “Paths”. Various empirical methods have been developed. For example, The Society of Naval Architects and Marine Engineers (SNAME) published the Design Guide for Shipboard Airborne Noise Control 1, which provides
23、a step-by-step empirical method to predict onboard ship noise levels. For the numerical analysis method, the statistical energy analysis (SEA) method is one of the more effective methods to predict onboard ship noise levels. It is efficient in addressing noise issues in complex structures at high fr
24、equencies. 3 Application These Guidance Notes can be used to assist in the noise analysis for ocean-going vessels. 5 Scope In these Guidance Notes, the following topics are discussed: i) Source-Path-Receiver Modeling ii) Results Evaluation iii) Empirical Method iv) SEA Method The Source-Path-Receive
25、r Modeling in Section 2 provides an overview of the modeling method of onboard ship noise analysis. It introduces methods for the modeling of the noise source, transmission path, and the receiver room. The Results Evaluation in Section 3 provides the basic concepts of evaluating the results of the n
26、oise analyses. It introduces the concept of frequency band analysis and the most widely-used weighting method, A-weighting method, to consider the sensitivity of the human ear. The Empirical Method in Appendix 1 provides the empirical formulae for the calculation of transmission attenuation from air
27、borne sound, structure-borne sound, and duct-borne sound. The SEA Method in Appendix 2 introduces the general concepts of SEA, which is a widely-used numerical method for onboard ship noise analysis. ABSGUIDANCE NOTES ON ONBOARD SHIP NOISE ANALYSIS .2018 1 Section 1 General 7 Relevant Documents ABS
28、Guidance Notes on Noise and Vibration Control for Inhabited Spaces ABS Guide for Crew Habitability on Ships ABS Guide for Crew Habitability on Workboats ABS Guide for Habitability of Industrial Personnel on Accommodation Vessels ABS Guide for Passenger Comfort on Ships ABS Guide for Comfort on Yacht
29、s ABS Guide for Compliance with the ILO Marine Labour Convention, 2006 Title 3 Requirements 9 Terminology Acceleration. A vector that specifies the time rate of change of velocity (units of m/s2(ft/s2). The acceleration of the vibratory motion of a structure can be specified in terms of the peak, av
30、erage, or root-mean-square (rms) magnitude of the acceleration in a given direction. In this document, the acceleration levels are given in terms of the rms acceleration amplitude. Airborne Sound (or Noise). Sound or noise that is transmitted through air. A-weighted Sound Pressure Level. The magnitu
31、de of a sound, expressed in decibels (i.e., 20 micropascals); the various frequency components are adjusted according to the A-weighted values given in IEC 61672.1 (2004) in order to account for the frequency response characteristics of the human ear. The symbol is LA, and the unit is dB(A). The mea
32、surement LAeqis an equivalent continuous A-weighted sound pressure level, measured over a period of time. Cavitation Inception Speed. Vessel speed at which a propeller starts to cavitate. Control Volume. A volume moving with constant flow velocity through which the continuum acoustic energy flows. C
33、oupling Loss Factor. It is a parameter unique to statistical energy analysis (SEA), which measures the rate of the energy flowing out of a subsystem through a junction to another subsystem. Damping. The dissipation of energy with time or distance. In this document, damping generally refers to dissip
34、ation of vibrating energy in structures. Damping Loss Factor. A parameter indicating the ability to dissipate the sound energy within the structures. Decibel (dB). A dimensionless unit of measure of the ratio of two quantities, P1and P2, each of which is equal to or proportional to power. Ten times
35、the logarithm to the base 10 of the ratio, P1/P2, has the dimensions of dB. Directivity. A measure of the directional characteristic of a sound source. Direct Sound Field. A sound field in which energy is flowing outward from the source without interference from surrounding surfaces. The sound field
36、 very close to a source, even in a reverberant room, is a direct field. Sound fields outdoors are direct fields at all distances from the source and are referred to as “free sound fields” or “free fields”. Dynamic Positioning (DP). A system to automatically maintain a vessels position and heading by
37、 controlling propellers and/or thrusters. Dynamic positioning can maintain a position to a fixed point over the bottom, or in relation to a moving object (such as another vessel). It can also be used to position the vessel at a favorable angle towards wind, waves, and current. Excitation. A time-dep
38、endent stimulus (force or displacement) that produces vibration. Excitation may be transient, random, and periodic. A steady-state periodic excitation, like that produced by propellers or propulsion engine, is of interest in these Guidance Notes. 2 ABSGUIDANCE NOTES ON ONBOARD SHIP NOISE ANALYSIS .2
39、018 Section 1 General Free Field. A sound field in a homogeneous, isotropic medium free from boundaries. The sound pressure level decreases by 6 dB per doubling of distance from the source. Free Velocity Level. The velocity level of the machine measured when it is mounted on sufficiently soft isolat
40、ors on a sufficiently stiff and heavy foundation. Frequency. The number of complete cycles of a periodic process occurring per unit time. Frequency is expressed in Hertz (Hz), which corresponds to the number of cycles observed-per-second. Frequency Band. An interval of the frequency spectrum defined
41、 between upper and lower “cut-off” frequencies. The band may be described in terms of these two frequencies, by the width of the band, and by the geometric mean frequency of the upper and lower cut-off frequencies (e.g., “an octave band centered at 500 Hz”). Joiner Panel. The inner side outfitting o
42、f the compartment, which covers the bulkhead and insulation. Level. In acoustics, the level of a quantity is the logarithm of the ratio of that quantity to a reference quantity of the same kind. The base of the logarithm, the reference quantity, and the kind of level need to be specified. Examples a
43、re sound power levels, sound pressure levels, and acceleration levels. Levels are always expressed in decibels (dB). Mass Law. The relationship between sound transmission loss and weight of the barrier. The mass law states that for every doubling of the weight of the material, a 6 dB increase in the
44、 transmission loss can be expected. Modal Density. Number of modes per Hertz. Octave Band. The frequency range bounded by upper and lower frequency limits fuand f, where fu= 2f. Octave bands are usually specified by their geometric mean frequency, called the band center frequencies. The standard oct
45、ave bands covering the audible range are designated by the following center frequencies: 31.5, 63, 125, 250, 500, 1000, 2000, 4000, 8000, and 16,000 Hz. The corresponding lower and upper frequencies are 22/45, 45/89, 89/177, 177/354, 354/708, 708/1416, 1416/2832, 2832/5664, 5664/11,328, 11,328/22,65
46、6. Radiation Efficiency. The radiation efficiency of a vibrating surface is proportional to the acoustic power radiated per unit surface area per unit of mean-square velocity of vibration averaged over the radiating surface. It is the measure of the efficiency with which a given surface converts vib
47、ratory energy to acoustic energy. Reverberant Sound Field. The part of the radiated sound field where the sound waves reflected from the boundaries of the enclosure are superimposed upon the incident field. The reverberant field may be called a diffuse field if a great many reflected wave trains cro
48、ss from all possible directions and the sound-energy density is very nearly uniform throughout the field. Statistical Energy Analysis. A numerical method for predicting the transmission of sound and vibration through structural acoustic systems. SEA method calculates the average response of the stru
49、cture and avoids a large quantity of calculation, which is efficient for large and complex structures. Sound Power. The rate at which sound energy is emitted, reflected, transmitted or received, per unit time. Sound Pressure Level. SPL, in dB, is 20 times the logarithm to the base 10 of the ratio of the pressure of this sound to a reference pressure. The sound pressure, p, is the root-mean-square value of the instantaneous sound pressure over a time interval at the point under consideration. Static Pressure. The pressure difference of air when flowing across a f
