Seminar acoustic engineering marineindustries

Handzettel 1
Unrestricted © Siemens AG 2014 All rights reserved. Smarter decisions, better products.
Acoustic Engineering Simulation
for the Marine Industries
Siemens PLM Web Seminar – 25.02.2015
Ir. Peter SEGAERT – Siemens PLM STS 3D – Leuven, Belgium
2014-06-17
Unrestricted © Siemens AG 2014 All rights reserved.
Page 2 Siemens PLM Software
Presentation Contents
Vibro-Acoustic Simulation Process
Intro STS - Noise & Vibration in Shipbuilding
2
Application 1 : Ship Hull Radiation3
Application 2 : Acoustic Signature4
1
Advanced Engineering for Marine Industry - Slide 2
5 Application 3 : Propeller Noise
6 Application 4 : Sonar Arrays

Handzettel 2
2014-06-17
 Worldwide leader in functional performance
engineering for transportation industries
Automotive – Aerospace – Railway – Shipbuilding
– Agricultural, Construction & Off-road
 Serving more than 100.000 R&D engineers
… in 5.000 manufacturing companies
 Top talent in 45+ offices worldwide
… 1.400 professionals
 Previously known as LMS, now business segment
STS = Simulation and Test Solutions of
Siemens PLM Software since 2013
 Our vision : “Closed-Loop Systems Driven Product
Development”
Siemens PLM STS = +30 years of Engineering
Innovation in Test & Mechatronic Simulation
55 %
25 %
20 %
Beijing
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Hamburg
Gottingen
Kaiserslautern
Madrid
Leuven
Liège
Lyon
Torino
Toulouse
Plymouth
Roanne
Torino
Yokohama
R&D &
Engineering
Centers
2014-06-17
Test-based Engineering
(modal, NVH, acoustics, durability)
Mobile, Laboratory
LMS SCADAS
Product Design Controls Engineering3D Simulation
Mechatronic System Simulation
System Synthesis System Data Management Multi-physics Modeling
PLM STS Product Range =
Closing the Loop between Simulation & Physical Test

Handzettel 3
2014-06-17
3D Simulation Solutions
CAE Software Suite for Multi-attribute Simulation
Acoustics & Vibration
Process Integration
Automotive
Mechanisms
• LMS Virtual.Lab Acoustics
• LMS Virtual.Lab Noise & Vibration
• LMS Virtual.Lab Correlation
• LMS Virtual.Lab Motion
• LMS Virtual.Lab Durability
• LMS Samtech TEA Pipe
• LMS Virtual.Lab Structures
Process Integration
Aviation
Wind TurbinesStructural Analysis
• CAESAM • LMS Samtech SAMCEF
• LMS Samtech Mecano
• LMS Samtech Rotors
• LMS Samtech Composites
• SAMCEF Wind Turbines
2014-06-17
Acoustic Comfort
• Work environm.
• Crew cabins
Industry solutions
• Decoupling
machinery
• Silent equipment
• Damping materials
Hull Radiation
• Water loading
effect on dynamics
• Directivity patterns
Industry solutions
• Estimate added mass
effect
N+V Transmission
• Vibration paths
• Sound paths
Industry solutions
• Engine room
shielding
• Transfer path
reduction e.g.
elastic couplings
Ship Engine
• Engine radiation
• Intake/exhaust
noise
Industry solutions
• Reducing engine
vibrations
• Flexible mounts
• Decoupling
connections to main
structure
Part 1 – Noise & Vibration in Shipbuilding
N+V Issues in Ship Design & Engineering (1)

Handzettel 4
2014-06-17
Sonar Design
• Ships
• Submarines
• Mines
Industry solutions
• Sonar arrays
• Sonar domes
• Towed sonars
• All around sonars
Propeller Noise
• Noise from blades
• Cavitation
Industry solutions
• Geometric design of
propeller blade
shape
• Propulsor ducts
Acoustic Scattering
• Stealth properties
Industry solutions
• Anechoic surface
tiles (rubber or
neoprene)
Acoustic Signature
• Hull radiation
• TBL noise
Industry solutions
• Decoupling of
machinery
• Anechoic tiles
• Improved
hydrodynamics
N+V Issues in Ship Design & Engineering (2)
2014-06-17
Overview of Frequency Range
• Noise & vibration sources in ships cover a large frequency range, from a
few Hz for hull vibrations, up to 10 kHz and higher for cavitation

Handzettel 5
2014-06-17
STS customers in Shipbuilding Industry (1)
• RUSSIAN FEDERATION : KRYLOV Shipbuilding ; RUBIN Design Bureau ; ATOLL Scientific
Research Institute
• AUSTRALIA: ASC (Australian Submarine Corp)
• UNITED STATES : MERCURY Marine; LOCKHEED-MARTIN ; NORTHROP-GRUMMAN shipyard ;
BOMBARDIER Outboard Marine ; Boston Whaler ; US Naval Postgraduate School
• JAPAN: KAWASAKI Shipbuilding Corp ; YAMAHA Marine ; MITSUBISHI Heavy Industries ; Japan
Defense Agency
• KOREA: ADD (Agency for Defense Development) ; HYUNDAI Heavy Industries ; DOOSAN Heavy
Industries & Construction ; SAMSUNG Heavy Industries
• SINGAPORE: DSO (Defence Science Organization)
• ITALY: FINCANTIERI [Cantieri Navali Italiani spa] ; CETENA
• FRANCE: THALES Underwater Systems (sonar systems) ; DGA ; INRS ; DCNS Lorient (French
Navy shipyard) ; Bassin des Carenes (ship hull naval research centre)
2014-06-17
STS customers in Shipbuilding Industry (2)
• GERMANY: THYSSEN-KRUPP Marine ; Germanischer Lloyd ; HDW [Howaldtswerke – Deutsche
Werft] ; MEYER Werft ; FWG Kiel
• NETHERLANDS: Koninklijke Marine
• UNITED KINGDOM: QINETIQ ; FRAZER-NASH Consulting ; THALES ; BAE SYSTEMS
• PR CHINA: Shanghai Marine Diesel Engine Research Institute ; Institute 726 ; Institute 715 ; Institute
701; Inst719 ; Inst702 ; Inst704 ; Institute 703 ; HARBIN Engineering University

Handzettel 6
2014-06-17
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1
2014-06-17
Part 2 — Vibro-Acoustic Simulation Process
The Source – Transfer – Receiver Model (1)
Acoustics = study of generation, propagation and reception of
compressional waves in an elastic medium (fluid or solid)

Handzettel 7
2014-06-17
The Source – Transfer – Receiver Model (2)
Sound Source
EM forces
ReceiverSystem Transfer
Flow-induced
pressure
fluctuations
Test data
Mechanical
vibrations
FEM Vibro-Acoustics
BEM Vibro-Acoustics
RAY Acoustics
Standard
Advanced
2014-06-17
The Philosophy — Data Flow Sequence

Handzettel 8
2014-06-17
In Real Life — LMS Virtual.Lab Process Flow
2014-06-17
Low freq ?
or
High freq ?
Harmonic ?
or
Transient ?
Interior ?
or
Exterior ?
Acoustic Simulation : four main questions !
Uncoupled ?
or
Coupled ?

Handzettel 9
2014-06-17
Time-domain Acoustics : wave equation
Acoustics = scientific study of generation, propagation, and reception of
sound waves
What is sound ??
• Small amplitude variations of pressure & density of an elastic medium (air,water)
around equilibrium values
• Propagation = longitudinal compression/rarefaction waves
Mathematical description = linear wave equation
• Wave propagation with sound speed c = [dp/d1/2
• Time domain description
• Contains all usual wave phenomena : refraction, reflection, diffraction
0
1
2
2
2
2




t
p
c
p
2014-06-17
Frequency-domain Acoustics
Time-domain wave equation => Fourier transform => Frequency-domain
equation
 p = complex pressure
 k = /c =  wavenumber
Helmholtz equation
• Frequency domain description - fully equivalent to wave equation
• Second-order linear partial differential equation
Covers all possible acoustic situations
• Interior acoustics = bounded domains
• Exterior acoustics = unbounded domains
• Interior/exterior combinations
• Presence of holes and openings
• Transmission
0~~ 22
 pkp

Handzettel 10
2014-06-17
Acoustic Configurations
 Cavity acoustics (interior)
 Sound radiation (exterior)
 Reflection/diffraction (exterior)
 Sound transmission (exterior/interior)
2014-06-17
FEM/BEM Fundamentals (1)
Finite Element Method Boundary Element method
• Higher modeling effort : 3D mesh Lower modeling effort : 2D mesh
discretization of fluid volume discretization of surface
• Modal-based approaches possible No modal-based approach
• Sparse matrices = Dense matrices =
faster computation longer computation
• Heterogeneous fluid Homogeneous fluid only

Handzettel 11
2014-06-17
FEM/BEM Fundamentals (2)
 BEM – Boundary Element Method for
exterior acoustic radiation simulation
 Modeling effort = only boundary mesh
representation needed
 Accuracy = Sommerfeld radiation
condition at infinity is guaranteed by use of
Green’s kernel function in BEM formulation -
no radiated power will be reflected from
infinity
 FEM – Finite Element Method for exterior
acoustic radiation simulation
 Modeling effort: = for exterior radiation, you
need engine boundary representation + an
outer boundary limit for the FEM domain + fill
volume in-between with fluid elements
 Accuracy = to satisfy the Sommerfeld
radiation condition, a ‘treatment’ has to be
applied at the outer FE mesh boundary to
model the unboundedness of the volume
around the vibrating structure, i.e. to ensure
that no sound waves are reflected from the FE
mesh outer boundary
2014-06-17
Pros and Cons of Acoustic FEM
• PRO - Acoustic FEM supports acoustic medium with heterogeneous
properties
• Temperature gradients and density gradients
(e.g. as occur in exhaust gas systems or water depth in underwater acoustics)
• Convection of sound waves due to high-speed main flow
• PRO - Acoustic FEM supports definition of bulk absorbing materials
• Mineral wools & foams as volume absorbers
• Modeling of poro-elastic absorption properties
• PRO - Acoustic FEM supports acoustic modal analysis
• PRO - FEM matrices have a sparse structure
• More speedy resolution than BEM, where matrices are dense

Handzettel 12
2014-06-17
Pros and Cons of Acoustic BEM
• PRO - Boundary Element mesh is a surface-type mesh
• Easier and faster modeling compared to FEM volume-type meshes
• Direct usage of an existing structural mesh
• Removal of small details (ribs) using VL Mesh Coarsening
• Remeshing with different mesh size using VL Mesh Coarsening
• PRO - Natural handling of typical acoustic configurations
• Unbounded (infinite) domain for acoustic radiation problems
(FEM requires Infinite Elements or PML/AML formulation)
• Openings, holes, etc… do not require special handling
(FEM requires equivalent impedance boundary conditions)
• CONTRA – Boundary Element Method requires homogeneous medium
• Different fluids are not allowed (e.g. water and air in the same model)
• Single-fluid medium cannot have strong temperature or density gradients
2014-06-17
Max Frequency Determines Element Size
Maximum frequency criterion for wave
simulation
• N elements required per wavelength l, in order to
have an accurate representation of wave shape
• Typical values : N=6 to N=10
There is a strong connection between frequency range and element size : higher
frequency means smaller element size, means more elements.
This puts a practical upper limit on the frequency range : the larger the object, the
lower the max analysis frequency will be.
max6 f
c
h 
Field variation in space
Fieldamplitude

Handzettel 13
2014-06-17
Max Frequency applied to FEM-BEM
Model size (number of nodes) of discretization methods
grows with frequency
• BEM n ~ f^2
• FEM n ~ f^3
Computation times scale with number of nodes
• Conventional BEM ~ O(n^3)
• Fast Multipole BEM ~ O(n log^2(n))
• Conventional FEM ~ O(n*b^2)
• …….
 Computation times become prohibitive at higher
frequencies!
However, several applications require support for:
• High frequencies: study of audio system acoustic performance
requires covering the full audible frequency range
• Large sizes: airplanes, trains, ships and submarines,
architectural acoustics
1 kHz BEM
18 knodes
4 kHz BEM
288 knodes
2 kHz BEM
72 knodes
2014-06-17
Max Frequency : Large diesel engine example
Due to the size of the model, 3 Boundary Element models have been considered, the calculation process
has been executed for each of them
0 – 1 kHz 1 – 2 kHz 2 – 3 kHz

Handzettel 14
2014-06-17
2
1
2014-06-17
Acoustic Comfort
• Work environm.
• Crew cabins
Industry solutions
• Decoupling
machinery
• Silent equipment
Hull Radiation
• Water loading
effect on dynamics
• Directivity patterns
Industry solutions
• Estimate added mass
effect
N+V Transmission
• Vibration paths
• Sound paths
Industry solutions
• Engine room
shielding
• Transfer path
reduction e.g.
elastic couplings
Ship Engine
• Engine radiation
• Intake/exhaust
noise
Industry solutions
• Reducing engine
vibrations
• Flexible mounts
• Decoupling
connections to main
structure
Part 3 — Ship Hull Radiation
Ship Hull Radiation & Added Mass Effect

Handzettel 15
2014-06-17
General Remarks
Objective Predict the noise field radiated from the hull due to
machinery vibrations : engines, pumps, motors,
electrical generators, etc.
Analyze the signature:
-Directivity patterns
-Structure-borne versus airborne contributions
-Identify structural modes particularly radiating
Design proper countermeasures:
-The right mounts
-Location where to modify structure
-Fitting of anechoic tiles to the hull
Particular
issues
Dynamics of the ship’s structure are changing
when immersed in water - structural resonances are
changing to lower frequencies due to water loading
Waterline is dependent upon ship loading conditions
and water temperature => different cases to
consider
2014-06-17
Hull Radiation - Physical Viewpoint

Handzettel 16
2014-06-17
Hull Radiation - Simulation Viewpoint
2014-06-17
Structural FEM coupled to Acoustic BEM (1)
Solution Virtual.Lab Boundary Element Acoustics
Benefits Accurately and efficiently models the water loading  start from ‘dry structural modes’
Assess directivity patterns
Creates insights (path contribution, panel radiation,…)  link mount forces to acoustics
Efficiently change the waterline
FEM Mesh
BEM Mesh
Modes
Radiation
Acoustic-structural coupling

Handzettel 17
2014-06-17
Model Courtesy of IABG
Objective:
• compute the acoustic field radiated by the
shell of the ship
Modeling:
• a boundary element mesh of the immersed
part of the ship
• a structural finite element model of the ship
• Infinite free surface (sea level)
Computation:
• Fully-coupled approach
Sound propagation in water: radiation due to structural vibration
2014-06-17
Automatic mapping from structural to acoustic mesh
Structural FE Model
• Contains volume elements
• Structural modal basis (dry modes)
 25 Mode Shapes, up to 25 Hz
Automatic Mesh Coarsening
• Replace volumes by their envelope
• Clean the surfaces
• End with the external shell
Acoustic BEM Model
• Only the underwater shell
• Wetted on one side only (Direct or Indirect BEM)
• Free half-space plane (p=0)
• Map ‘finer’ structure onto ‘coarser’ acoustic
mesh
 Mesh mapping
 Modes mapping



Handzettel 18
2014-06-17
Radiated sound field
Results (mode #9 - 8 Hz):
• The structural deflection on the ship, including coupled modes (added mass effect)
• The underwater field radiated by the shell.
Design changes?
 Structural modification (change the modes)
 Mechanical isolation (reduce the excitation)
 Acoustic treatment (decouple the radiation)
2014-06-17
Analyze noise with and
without water loading:
inspect mode shifting
Analyze directivity
patterns
Colorbar displays to
identify efficiently
critical areas
Acoustic Power
Analysis

Handzettel 19
2014-06-17
Example : Hyundai Heavy Industries
 Challenge
 The customer is experiencing problem with the ship sonar
operation because of high underwater tonal noise from ship
engine.
 Need to improve design to reduce noise radiation
 Solution
 LMS Virtual.Lab NVH to analyze energy transfer path from engine
vibration to noise radiation
 LMS Virtual.Lab Vibro-Acoustics to evaluate the effect of an
additional damping structure
 Result:
 Customer was able to design the damping and absorptive system
to reduce hull vibration and noise radiation by 10 dB
Source:
B. H. Yoo, J. H. Park W. H. Joo and K. D. Lee:
“Numerical Analysis and Practical Proposition to Reduce Underwater
Radiated Noise from Submerged Hull”,
Inter-Noise 2004, Prague, Czech Republic, August 22-25, 2004.
2014-06-17
Model Courtesy of QinetiQ
Reference:
ICSV11 Conference, 2004
Example : Torpedo Hull Radiation (1)
Features
• Heavy fluid = water
• Fully-coupled fluid-structure interaction
• Acoustic source at large distance
• Test using reciprocity principle
Objectives
• Radiation due to internal force
• Experimental verification

Handzettel 20
2014-06-17
Example : Torpedo Hull Radiation (2)
Fully-coupled approach
• Structural flexibility included
• Modal model of structure
• Interior acoustic ‘void’ with structural elements (only exterior
wetted)
• Acoustic BEM coupled solution
Acoustic BEM mesh
+ Structural mode
shapes
BEM Coupled solution
(structural forces)
Acoustic
Radiation field
2014-06-17
Experimental Verification (1)
Reciprocity Principle
• Open-water test facility
• Acoustic source
• Structural response measurements (v)
Structural Correlation
• Modal analysis in air
• Modal correlation / updating
Hydrosounder
Hydrophone
Cylinder
Water surface
16m
1m
Support
for
cylinder
QStrengthSource
vVelocity
FforceExcitation
ppressurefieldFar
,
,
,
,

Model Experiment

Handzettel 21
2014-06-17
2014-06-17
20 dB

Handzettel 22
2014-06-17
2
1
2014-06-17
Sonar Design
• Ships
• Submarines
• Mines
Industry solutions
• Sonar arrays
• Sonar domes
• Towed sonars
Propeller Noise
• Cavitation
Industry solutions
propeller blade
shape
• Propulsor ducts
Acoustic Scattering
Industry solutions
tiles (rubber or
neoprene)
Acoustic Signature
• Hull radiation
• TBL noise
Industry solutions
• Decoupling of
machinery
• Anechoic tiles
• Improved
hydrodynamics
Part 4 — Acoustic Signature
Acoustic Stealth & Sonar Scattering

Handzettel 23
2014-06-17
Acoustic Stealth
Objective Make the ship or submarine more ‘stealth like’
Analyze the scattered field:
-Minimize the reflected field
Design proper countermeasures:
-Fitting of anechoic tiles to the hull
-Shape
From low to mid frequency sonar wave excitation
Particular
issues
Effects of the flexibility of the ship on the
scattered field
Sound waves hitting from different angles
2014-06-17
 Objective:
 Optimize the acoustic signature of the submarine (frequency response), scattered
field
 Modeling:
 Structural FEM modal model plus physical BEM acoustic model
 Interior ‘void’ in acoustic model (no fluid)
 Acoustic source at large distance: Incident plane wave, arbitrary angle
 Computation:
 Fully-coupled approach >< Uncoupled approach
Model Courtesy of IABG
Sound propagation in water: scattering of incident sound wave
Scattering of Sound from a Rigid/Flexible Submarine

Handzettel 24
2014-06-17
Scattering with Acoustic BEM
Solution Virtual.Lab Boundary Element Acoustics
Benefits Analyze the scattered field from different angles efficiently
Efficiently run and analyze different designs and different loading conditions
BEM Mesh
Incident wave
2014-06-17
Scattering with Acoustic FEM
Solution Virtual.Lab FEM AML - Virtual.Lab FEM Acoustics
Benefits Analyze the scattered field from different angles efficiently
Efficiently run and analyze different designs and different loading conditions
FEM Mesh with AML Property
Incident wave
FEM
analysis

Handzettel 25
2014-06-17
Sound Field Results at 1000 Hz
Total pressure field for plane
wave excitation
Scattered pressure field
2014-06-17
Influence of Surface Treatment
WITH surface treatment
(sound absorbing tiles)
without surface treatment

Handzettel 26
2014-06-17
Rigid versus Flexible Analysis
Rigid Frame Flexible Frame
Effect of the flexibility of the
structure take into account
in the scattered field
2014-06-17
2
1

Handzettel 27
2014-06-17
Sonar Design
• Ships
• Submarines
• Mines
Industry solutions
• Sonar arrays
• Sonar domes
• Towed sonars
Propeller Noise
• Cavitation
Industry solutions
propeller blade
shape
• Propulsor ducts
Acoustic Scattering
Industry solutions
tiles (rubber or
neoprene)
Acoustic Signature
• Hull radiation
• TBL noise
Industry solutions
• Decoupling of
machinery
• Anechoic tiles
• Improved
hydrodynamics
Part 5 — Propeller Noise
Sound Field from Propellers using CFD
2014-06-17
E.g. torpedo, submarine or other systems
Objective Predict the noise radiated by the propeller :
Tonal noise component; multiple of Blade Passing
Frequency (BPF)
Propeller is a major component of the acoustic
signature. The circumferential variation on Axial
Instream Velocity causes harmonic loading content
for the blades 1st public display
of submarine propeller
CFD path lines

Handzettel 28
2014-06-17
Propeller Noise Classification
Propeller Noise
Non Cavitating Cavitating
Blade Tonals (RPM * n blades * m) NOT POSSIBLE
Broadband Noise
Due to turbulence and trailing edge vortices NOT POSSIBLE
Propeller Singing
In case vortex shedding frequency corresponds to the blade
resonance frequency NOT POSSIBLE
2014-06-17
Technical base = Aeroacoustics
Solution Virtual.Lab Boundary Element Acoustics - Virtual.Lab Aero-Acoustics
Benefits Timely prediction of flow-induced noise for every design loop
Exploits at best the complementarities between low-order CFD and acoustic propagation
codes
Unique approach on the market, enforcing the correct radiation characteristics of the
source region
Find possible noise issues and suggest design improvement
Convert to Lighthill equivalent Fan source
BEM / FEM propagation
CFD calculation
on propeller
BEM or FEM mesh of structure

Handzettel 29
2014-06-17
AeroAcoustic Sources (Lighthill analogy)
Unsteady
Flow
Moving Surfaces
Steady Surfaces
No Surfaces
(or smooth
surfaces)
Quadrupoles
Dipoles on surfaces + Quadrupoles in wake
Rotating Dipoles + Quadrupoles in wake
2014-06-17
Propeller coupled response to structural excitation -
Underwater radiation pattern

Handzettel 30
2014-06-17
Adobe Acrobat
Document
Some Academic References
Non-uniform flow conditions into the
propeller cavitation; prediction and
validation
Qiong Yang Fang ; Wang Yongsheng
Naval Ships and Power Engineering
Wuhan University
Adobe Acrobat
Document
2014-06-17
2
1

Handzettel 31
2014-06-17
Sonar Design
• Ships
• Submarines
• Mines
Industry solutions
• Sonar arrays
• Sonar domes
• Towed sonars
Propeller Noise
• Cavitation
Industry solutions
propeller blade
shape
• Propulsor ducts
Acoustic Scattering
Industry solutions
tiles (rubber or
neoprene)
Acoustic Signature
• Hull radiation
• TBL noise
Industry solutions
• Decoupling of
machinery
• Anechoic tiles
• Improved
hydrodynamics
Part 6 — Sonar Arrays
Analysis of Sonar Transducer Arrays
2014-06-17
SONAR Transducer – Solution Process
2. Vibroacoustic field solution with the Direct Nodal
BEM or with FEM PML/AML
• Computes the full coupled acoustic field and the
structural excitation: field potentials and modal
participation factors
• Exports modal part. factors to *.unv file to ATILA
ATILA FEM
Compute structural dynamics
Virtual.Lab Acoustics:
Compute coupled
vibroacoustic field solution
1. Structural modal solution with the Finite Element
Method
• Computes the ‘dry’ structural modes: shapes,
frequencies, forces
• Exports modes to *.unv file to Virtual.Lab
3. Electromechanical interaction
• Takes the modal participation factors from Virtual.Lab
• Computes the electric field and structural
displacements/stresses

Handzettel 32
2014-06-17
Example 1 – Piston piezo-electric transducer
Comparing DBEM and FEM AML
Comparison between Atila –Virtual.Lab DBEM and Atila –Virtual.Lab FEM AML for a piston
piezoelectric transducer (length x diameter = 40 mm x 8 mm) fully immersed.
Resonance frequency at 25 kHz.
DBEM
FEM AML
Deviation in directivity:
max 0.2dB
2014-06-17
ATILA/Virtual.Lab FEM AML simulation of
• Single piston transducer
• Six elements array with front plate
• Maximum response frequency changes from
101 kHz to 95 kHz
• Directivity shows considerable adjustment
Example 2 – Side scan sonar array
Single element versus 6-element array
Stress and displacement
Transmitted
Voltage Response
Directivity
Single
piston
Array
with front
plate

Handzettel 33
2014-06-17
DBEM, full immersion
Example 2 – Side scan sonar array
Full immersion versus one-sided water contact
 FEM AML one-sided
water contact, rigid
baffle
 Near field and directivity at 95 kHz
2014-06-17
Example 3 – Multi-beam Sonar Array
Sonar beam steering by voltage phasing
5x5 rectangular elements, resonant frequency
42kHz
One-sided water contact: Atila – Virtual.Lab FEM AML
Two cases: unsteered beam and beam steered at 30°

Handzettel 34
2014-06-17

Seminar acoustic engineering marineindustries

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