dirk von werne, siemens plm software predicting structure borne tonality · pdf...

Restricted © Siemens AG 2014 All rights reserved. Smarter decisions, better products.

Predicting structure borne tonality

contributions – a hybrid test-

simulation method

Dirk von Werne, Siemens PLM Software

2014-10-17

Restricted © Siemens AG 2014 All rights reserved.

Siemens PLM Software

Overview

Background-Tonality

Transfer Path Analysis – Principle

Field Testing

Test-based Analysis and Troubleshooting

Test-Simulation Hybrid Process

Simulation Results from Validated FE Model

Use of Validated Model: Mitigation of Tonality

Outlook – Towards a Fully Virtual Prediction

Conclusions

2014-10-17



Summary

Structure borne tonality noise from gearbox or generator:

Challenging to diagnose and mitigate on system level.

Transfer paths and noise radiating panels difficult to confirm

Test-Simulation hybrid process:

Good ability to confirm Transfer paths and noise radiating panels

Operational and transfer testing:

Data for model validation

Excitation for simulation process

Insight in fundamental phenomena

Simulation with validated vibro-acoustic model:

Structural model loaded with equivalent excitation from test

Vibration response forms the boundary condition for noise radiation.

Model can be exploited for

detailed operational deflection shapes

transfer paths and acoustic panel contributions

Design modifications can be applied in the virtual world first to check their effectiveness.

.

2014-10-17



Background

Tonality

From gearbox or generator

input

Airborne or structure borne –

structure borne typically at

lower frequencies

Often a matter of system

integration

‘Good’ gearbox plus ‘good’

turbine not necessary free of

tonality0

10

20

30

40

50

60

70

80

1 10 100 1000 10000 Frequency (Hz)

So

un

d P

ressu

re L

evel (d

B)

138.8dB 105.0dB

133.3dB 104.6dBA

132.5dB 103.3dBA

135.7dB 101.4dBA

135.0dB 101.8dBA

Lw LwA (unweighted)

L5

1525kW

L4

802kW

L3

600kW

L2

415kW

L1282kW

SOUND POWER LEVEL

AERO

1fz2

2fz2

1fz3

3fz1

4fz1

2fz3

LOW FREQUENCY

20-200Hz

MEDIUM FREQUENCY

200Hz-2kHz

HIGH FREQUENCY

2-20kHz

INFRASOUND

(inaudible or subsonic)

LOW FREQUENCY

20-200Hz

MEDIUM FREQUENCY

200Hz-2kHz

HIGH FREQUENCY

2-20kHz

INFRASOUND

(inaudible or subsonic)

SOME 1.5 UNITS SHOW UNACCEPTABLE LOW & MID FREQUENCY AUDIBLE TONALITY

10dB

2014-10-17



Test

Simulation

Transfer Path Analysis, principles

Goal: System Characterization,

Identification of contributions.

Breaking down noise and vibration phenomena into source-transfer-receiver

System characteristics

- structural

- acoustic

Operating loads

- structural

- acoustic

= x

Receiver Transfer path Source

2014-10-17



Transfer Path Analysis:

Force identification

Transfer Path Analysis on Wind-turbine

•Operational measurements at rotor & gearbox

•FRF measurements & force identification

•FRF=Frequency Response Function

=Transfer Function

•Forward prediction to far-field

Farfield noise

Rotor

Tower

Gearbox

F1

x4

x3

T14

T13

F2T24

T23

224114214

223113213

..,

..,

FTFTFFfx

FTFTFFfx

2

1

2414

2313

4

3

F

F

TT

TT

x

x

4

3

1

2414

2313

2

1

x

x

TT

TT

F

F

F : Excitation

X : Response

T : Transfer Function

2014-10-17



OPERATIONAL DATA TESTING

Measure up to 400 data points

Steady state or run-up

TARGETS

Measure Transfer functions

Derive input dynamic forces

Measure all necessary vibration responses

including system transmission and radiating

panels

Measure all necessary acoustic responses:

cavity internal, external acoustic pressure

and far field response

> Provide input, output responses and all

intermediate transfer function data to

validated FE model

THE UNIT

Analysis of Wind Turbine TonalityField testing

2014-10-17



Test setup scheme

Microphones

(Far Field)

LMS Scadas mobile

Nacelle

LMS Scadas mobileIn Rotor

Hub

IRIG-B GPS receiver

Bottom of Tower

LMS Scadas III

LAN cable

LAN connection

through slip ring

Includes input

from wind turbine

operation:

Torque, current,

pitch angle, yaw

angle, etc.

simultaneously

tracked

2014-10-17



Test Based Analysis and Troubleshooting

Powerful diagnosis tool, e.g. Operational Deflection Shape (ODS)

In a hybrid Test-Simulation process, the missing contribution information can be

retrieved from simulation.

Also Transfer Path analysis, mount

isolation, averaged spectra by component,

modal analysis, ….

But:

No reliable information about noise

radiating surfaces

Difficult to identify transfer paths over

large bearings and other line connections

– typically no opportunity to disconnect

components

2014-10-17



Analysis of Wind Turbine Tonality

Hybrid Process

FE Modeling

Assembly

Updating

Model

Assembly/Reduction

Component Model

Building

Component Models

Wrapping/

acoustic Modeling

Assembly Models

Component

Updating

FE Modeling

Experimental

Modal Analysis

Experimental

Modal Analysis

Acoustic response

Acoustic Analysis

Validated FE model

Loads (Test – CAE)

SimulationTest

2014-10-17



ACOUSTIC

RADIATION ATV

X

SURFACE VIBRATION VELOCITY

ATV acoustic transfer vectors

FE structural model BC [m/s]

=

ACOUSTIC RESPONSE

Sound Pressure Level

ATV BASED RESPONSES ALLOWED TO PERFORM DESIGN ITERATIONS

Analysis of Wind Turbine Tonality

Validated model responses

Ranking of Radiation Components

2014-10-17



Use of Validated Model: Mitigation of Tonality

Exploit validated model for

• Contribution analysis

• Concept modifications

• Parameter studies

• Detailed design modifications

Reduced model for fast concept modifications

2014-10-17



Outlook – Towards a Fully Virtual Prediction

Can we use upfront simulation without involving test data?

Find big issues, identify phenomena => possible now

Vibro-acoustic transfer functions to identify system sensitivity for drivetrain matching

to support gearbox/generator requirements => possible in short term

Accurate prediction of noise and tonality => some more work required

:

2014-10-17



Conclusions

Putting together the strengths of testing and simulation methods, a hybrid

process to diagnose wind turbine tonality has been developed and demonstrated

Test giving insight in global phenomena, providing operational deflections, forces

and transfers

Model validation

Simulation providing detailed deflection shapes, radiation contributions

Fast iteration of concept and design modifications

dirk von werne, siemens plm software predicting structure borne tonality · pdf...

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