Identification of Aerodynamic Sound Source of Industrial ...aero.me.tut.ac.jp/ISFV2014.pdf · 2014/6/30 1 ISFV2014 (Okinawa) 2014.06.26 0 Identification of Aerodynamic Sound Source

2014/6/30

1

2014.06.26ISFV2014 (Okinawa)ISFV2014 (Okinawa)ISFV2014 (Okinawa)ISFV2014 (Okinawa)

0

Identification of Aerodynamic Sound

Source of Industrial Applications

Toyohashi University of Technology

Akiyoshi Iida

The 16th International Symposium on Flow Visualization

These animations are not related to the today's topics


1

Late Suzuki Yoichi, Technician of MERL Hitachi Ltd.,

Designed and manufactured 4 low-noise wind tunnels

Designed and manufactured Microphone array

Dr. Hiroshi Yokoyama, Assistant Prof. of Toyohashi Univ. Tech.

Development of Direct Aeroacoustic simulation

Acknowledgment

2014/6/30

2


2

HPCI (High Performance Computer Infrastructures ) Project

Prof. Kato (Univ. Tokyo), Prof. Yoshimura (Univ. Tokyo),

Prof. Tsubokura (Hokkaido Univ.), Mr. Yamade (Mizho)

Mr. Hashizume (Suzuki), Mr. Iida (Suzuki), Dr. Miyazawa (Honda)

Time resolved PIV applied for Aeroacoustic Research

Dr. Uda (RTRＩＩＩＩ)，，，，Mr. Yamazaki (RTRI), Dr. Takaishi (JAXA)

Prof. Hayami (Kyusyu Univ), Prof. Okamoto (Univ. Tokyo)

Prof. Someya (Univ. Tokyo)

Acoustic Measurement with Microphone Array

Dr. Takano (Hitachi), Ms. Aizawa (Hitachi)

PSP Measurements for Fan Noise Identification

Prof. Fuji (JAXA), Prof. Asai (Tohoku Univ.), Prof. Kameda (Tokyo Univ. Agri. Tech)

Measurement of Turbulence and Aerodynamic Noise

Prof. H. Makita (Toyohashi Univ. Tech), Dr. T. Otaguro (Hitachi)

Prof. Toyoda (Hokkaido Inst. Tech.), Prof H. Fujita (Nippon Univ.)

Dr. Y. Suzuki (Nippon Univ.)

Special Tanks to


3

• Motivations and Background

• Theory and Methodology

Lighthill Theory

• Topics of Aerodynamic Noise Research

Noise Source Identification of High-speed vehicle

Measurement of Source Term of Lighthill Theory

Surface Pressure (From Press. Trans to PSP)

Vorticity (From Hot-wire to Time-resolved PIV)

Numerical Simulation

Development of Low Noise Pantograph

Acoustic Resonance & Feedback (Direct CAA)

• Summary and Future work for young Researchers

Outline

2014/6/30

3


4

The final goal :

Clarify the Generation mechanism of aerodynamic noise

Reduction of aerodynamic noise from industrial applications

Motivation


5

1987 : Division and privatization of Japan National Railways

Train speed : 220km/h → 360km/h (Development goals)

Sources: Machinery, Rolling Noise and Aerodynamic Noise

First Project

Vehicle speed

SPL

Machinery

noise

Rolling noise

Aerodynamic noise

I II III

Total noise V6 -9

V

V2 -3

2014/6/30

4


6Crossover Speed of Dominant Sources

50

55

60

65

70

75

80

85

90

95

100

100 1000

Vehicle Speed [km/h]

SP

L

[

dB

(A)]

Total noise

Vt

Total aerodynamic noise

Rolling

noise

300 500

Without noise barriers

50

55

60

65

70

75

80

85

90

95

100

100 1000

Vehicle Speed [km/h]

SP

L

[

dB

(A)] Total noise

Rolling noise

Total aerodynamic noise

Vt b

500300

With noise barriers

Barsikow and Mller, Proc. STECH '93 Vol. 2, 49 (1993)


7

Aeroacoustic Research Project of MERL Hitachi Ltd.,

Microphone Array

Dr. Takano

Wind tunnel Experiments

Prof. Fujita

Dr. Otaguro

Numerical Simulation

Prof. Ikegawa

Prof. Kato

360Project

2014/6/30

5


8Lighthill Theory

( )

i

i

ji

jii

i

iii

i

iii

ji

ji

i

i

j

j

i

s

i

i

ji

j

i

j

j

Fx

vvxxx

ct

Fxx

c

xF

xx

p

xvv

xxv

tx

x

v

ttt

xt

pc

Fx

pvv

xv

t

x

v

t

∂∂

−∂∂

∂=

∂

∂−

∂∂

∂∂

+∂

∂∂∂

−=∂∂

+∂∂

∂∂

−=∂∂

∂∂

+∂∂

∂∂

=∂

∂

∂∂

+∂∂

∂∂

∂∂

∂∂

∂∂

=

+∂∂

−=∂∂

+∂∂

=∂

∂+

∂∂

ρρρ

ρρρ

ρρ

ρ

ρρ

ρρ

2

2

22

2

2

2

0

Eq.(2)-Eq.(1)

(3)........................................

Sound of Speed ofEquation

..(2)..........

Equation Momentum

.....(1)..............................0

EquationContinuty

Sir James Lighthill

Source Term


9Difficulty of Aerodynamic Noise

( ) ( ){ } ijijjiij

ij

ji

ppcvvT

Txx

ct

σδρρρ

ρ

−−−−+=

∂∂∂

=

∇−∂∂

00

2

222

2

Non-linear term Compression term Viscous term

Source Term

Tij: Lighthill Tensor

In industrial point of view

Source term and propagation medium is same

Noise levels increase 6 to 8th Power of Flow velocity

・・・・Aerodynamic noise is generated by unsteady fluid motions.

・・・・Lighthill equation is exactly the same as NS equation.

・・・・Lead to analytical solution is difficult as well as NS equation

・・・・Require much computational resources

( from the difference of time and space scale.)

2014/6/30

6


10Microphone ArrayTheory of Beam forming

(Fix Focus Model)

S0

p0 pj

∑=

−=

M

i ij

iji

jtr

ctrtStp

1 )(

)/)(()(

rij

Frequency limit

Upper Limit : ∆x

Lower Limit : L and Time const.

20m Horizontal Array : 300Hz

C: The speed of SoundS1 Si

∆x

L


11

Moving Focus Method (Barsikov & King 1985)

Moving Focus Method

∑

∑

=

=

+⋅

=N

j

ijij

N

j

ijjjij

i

trW

ctrtPAW

tS

1

1

/

)}(/{

)}/)(({

)(

2

0

2)()( rVtxxtr jiij ++−=

p0 pj

Si

∆x

Si

V

Frequency limit

Upper Limit : ∆x

Lower Limit : L and Time const.

5m Horizontal Array : 100Hz

2014/6/30

7


12Two Dimensional Array

Mic. Amp

Power Supply

96ch. A/D Converter

Gain.c

array.c

fft_array.c

Data Plot

Noise Source

Pa

Pm2

r i

Pm1

Pmn

Microphone Array

-0.6-0.4

-0.20

0.20.4

X [m]-0.6

-0.4-0.2

00.2

0.4

Y [m]

-20

-15

-10

-5

0

-20

-15

-10

-5

0

|P|2 [dB]


13

69 Microphones (1/2 Microphones)

Array Length : 6m××××6m

Distance between array and train : 5m

Frequency range: 100 Hz ~ 4kHz

4 Analog Data Recorders (TEAC X7000)

X-shaped Microphone Array

2014/6/30

8


14Noise Source Distribution

Time (sec)

SP

L

dB

(A)

45

50

55

60

65

70

75

80

0 1 2 3 4 5 6 7

Pantographs

Leading head

Overall

Rail and wheel

270km/h

Cable heads

Car bodies

with noise barriers


15Unresolved Issues

In acoustical Point of View

・・・・Noise source is defined by Microphone Array

・・・・Dominant Noise Source is defined (Aerodynamic Noise)

I can't get no satisfaction from the results as aerodynamicist

Go back to Lighthill Theory

34 36 38 40 42 44 46 48 50 52 54

2014/6/30

9


16Lighthill Acoustic Analogy

∫ −∂∂

π= dSctpn

t

x

cp

i

i

a)/,(

4

12

xyx

Lighthill-Curle’s Theory

ydyYcxtyutxc

xtXp i

i 3

02

0

0 )()/,()(4

),( ∇•−×ω∂∂

π

ρ−= ∫

Powell’s Vortex Sound Theory

P : Surface Pressure Fluctuation

Solution of Lighthill equation in Low Mach Number Flows

ω :Instantaneous Vorticity vector

∇∇∇∇Yi: Compact Green function (Scattering function)


17Measurement of Surface Pressure

0.375D

θ

D=40 mm

L=500 mm

ZY

X

Z=250mm

Z=-250mm

0

Flow

Pressure Ports

d=1 mm

D=40 mm

Pressure Port

1/2 inch

Microphone

Microphone

Amplifier

2014/6/30

10


18Surface Pressure Fluctuation

20

30

40

50

60

70

80

90

100

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Dimensionless frequency f*

P

ow

er

spectr

um

P

2(f

*)

[

dB

]

Z/D

0.000.75

1.503.75

Re=104

U=3.75 m/s

D=0.04 m

θ= 90 deg

O.A.


19Noise from Two Point sources

Pa r

ldU S C Lt L crms2

2

2

2

2

6 2 2 2

8=

ρ θ .........Curle

cos(Re)

Lc

Coherent Structure

U=30 m/s, SPL=65 dB

D

Incoherent Structure

U=30 m/s, SPL=55 dB

d

D

Lc

Lc Lc=4D =1.2D

Phase difference zero

+6dB

Independet source

+3dB

ＣｏｒｒｅｌａｔｏｎＣｏｒｒｅｌａｔｏｎＣｏｒｒｅｌａｔｏｎＣｏｒｒｅｌａｔｏｎｌｅｎｇｔｈｌｅｎｇｔｈｌｅｎｇｔｈｌｅｎｇｔｈPhillips JFM vol.1

2014/6/30

11


20Spanwise Coherence

Re=104 90degSt=0.2

St=0.4St=0.6


21Estimated SPL (with Cohelence)

10

20

30

40

50

60

70

0 0.2 0.4 0.6 0.8 1 1.2

Dimensionless frequency f*

SP

L

(dB

)

Re=4 ×××× 104

U=15.0 m/s

D=0.04 m

Curle's Equation

Measurement

2014/6/30

12


22Effect of Coherence

measured

LES

LES (coherence considered)

(dB)

80.0

60.0

40.0

20.0

0 1.0 2.0 3.0 4.0 5.0

f (××××103 Hz)

SP

L

測定点測定点測定点測定点ノズルノズルノズルノズル

音音音音

後流後流後流後流ReD=104

一様流一様流一様流一様流U∞∞∞∞＝＝＝＝15 m/s

円柱円柱円柱円柱D＝＝＝＝0.01 m

1 m

L=12.5D

L=4D (Periodic boundary condition)

Wind tunnel Experiment

Numerical simulation

Over estimate: w/o coherence


23Noise Reduction Idea from C.L.

20

30

40

50

60

70

80

100 160 250 400 630 1k 1.6k 2.5k 4k 6.3k 10k O.A.

Frequency [Hz]

SP

L [

dB

(A)]

Circular Cylinder

with small holes

Circular Cylinder

Background noise

of wind tunnel

2014/6/30

13


24What is the Real Source?

Acoustic Analogy gives us;Quantitative estimation of aerodynamic sound

Guidelines for noise reduction with coherence function

But, still, we do not know "which vortex" generates sound.

To find the real sound source

related to unsteady fluid motions

Vortex Sound Theory


25Vorticity Measurement2.6 m

Circular CylinderD=0.04m L=0.5m

Contraction Nozzle 9:1

Uniform Flow VelocityUo=15m/s

Traverse Unit

Control Unit

0.5

m

Static Pressure ProbeI-X-I Hot-wire probe

Z X

Y

0

Surface Pressure

Amplifier (12ch)

Static Pressure

Amplifier (1ch)

Hot-wire

Anemometer (4ch)Traverse Controller

12bit 64ch

A/D Converter

2.6 m

φ7

54.8

8PressureHoles φ0.4

(34.3)(10.2)

(1)

Steel Tube φ1.06

1/4inchCondenserMicrophone

Static Pressure Probe

Developed by Prof. Toyoda

Prong φ 0.2 Ceramic Tube φ 0.9

0.5

2.0

2.0

1.4

0.7

6 20

φ 4

2014/6/30

14


26Coherent Output PowerEstimate surface pressure Pc which is attributed by vorticity

(Coherence between Static Pressure and Surface Pressure)

)()()(

)()( 2

2

2fP

fGfG

fGfP

pw

wp

c =

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

-0.5 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5

X/D

Z/D

Pc

Vroticity motion

Aerodynamic sound


27Modified Curle’s Eq.

Modified Curle’s equation, replacing P with Pc

2

422

2

16

1)(

= ∫S ciicsource dSPnt

xLLxa

xp∂∂

π

Conventional Method

Surface pressure

Curle’s Equation

Aerodynamic Noise

Proposal Method

Surface pressure

Coherent Output Power

Modified Curle’s Equation

Noise source distribution

2014/6/30

15



45

45

45

45

50

50

50

50

55

55

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

-0.5 0 0.5 1 1.5 2 2.5 3 3.5

X/D

-0.2

0

0

0

0 0

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

-0.5 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5

X/D

ψ= 0

-0.5 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5

X/D

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

Y/D

ψψψψ =0

Contours for

static pressure coefficient

Velocity field around a cylinder

Contour of Sound Source


29LimitationsIt is limited to the phenomenon

that can be applied to the phase-averaged method.

It is difficult to applying three-dimensional flow.

It can not be measured near the surface of body.

(The problem of placement of the probe)

Candidates of the Dominant Source of aerodynamic noise

Vortices near the body surface

Strong Scattering effect

Vortices around the vortex formation region

Strong deformation of Vortex

Applied to Time-resolved PIV for aeroacoustic research

2014/6/30

16


30Measurement System

Seed Generator

High Speed

Camera

Cylinder

D=6mm

Mirror

Laser Sheet

Microphone

LaserLaserLaserLaser Nd:YLF Laser, 512nm

FrequencyFrequencyFrequencyFrequency 10 kHz (dual cavity)

PowerPowerPowerPower 10 mJ @ 1kHz

Frame RateFrame RateFrame RateFrame Rate 10 kHz

ResolutionResolutionResolutionResolution 1024×648 pixel

Light SourceLight SourceLight SourceLight Source

HighHighHighHigh----speed Cameraspeed Cameraspeed Cameraspeed Camera

Sampling Freq.Sampling Freq.Sampling Freq.Sampling Freq. 5 kHz

Measurement Freq.Measurement Freq.Measurement Freq.Measurement Freq. ～ 2.5 kHz

Noise MeasurementNoise MeasurementNoise MeasurementNoise Measurement

Wind TunnelWind TunnelWind TunnelWind Tunnel

VelocityVelocityVelocityVelocity 15 m/s

CylinderCylinderCylinderCylinder D= 6mm

ReReReRe 6000

Dr. Uda (RTRI)

Prof. Someya( U. Tokyo)


31Two Plane Measurement

Δz

Reference Plane

Moving Plane

Reference PlaneMoving Plane

polarizing plate (0deg)

Moving Plane

Block the light of reference plane

(0deg)

polarizing plate (90deg)

2014/6/30

17


32Experimental Conditions

Number of Grids 73x27

Interrogation area 24 px

Data Algorithm Multi-grid

Sub pixel Analysis 3-point Gauss

exposure time of Plus 10 µs

Number of Average 9500


33Coherence & Phase Measrement

25

0

Velo

city

[m/s

]

-3 0 3 6 9 12 15 18 21

X [mm]

-3

0

3

Z[m

m]

[0,0]

-3 0 3 6 9 12 15 18 21

X[mm]

-3

0

3

Z[m

m]

[0,0]

Y [

mm

]Y

[m

m]

∆φ(x, y)

∆φ(x, y)

∆ψ(x, y, z)

Reference Plane

Moving Plane

2014/6/30

18


34Estimated SPL


35Distribution of Noise Source Term

①①①①Near the Separation Points ②②②②formation region of Karman vortex(2) St = 0.3

(3) St = 0.4

(2) St = 0.3

(1) St = 0.2

Two Strong Noise Sources

①①①① Around Separation Points

②②②② Formation Region of K.V.

2014/6/30

19


36Contribution of Scattering

Scattering Function is concentrated

around the separation points


37Dominant Source Region

Coherence

Power levels

（（（（Microphone））））

Noise Source Distribution

Sound Pressure level

Contribution of Far Field Sound

1. Separation Points: Low

2. Formation Region of K.V. : High

2014/6/30

20


38Contribution of Integration Area

Dependence of the integral range

for the spectrum

Noise levels of Fundamental Freq.

Sound pressure levels increase at

the formation region of Karman

vortex

From Lower Limit x/D=-1.0 to Upper Limit x/D=-0.5 ~ 4.4


39Development Doctor Yellow

Pantograph for Current collection

Pantograph for Inspection

Doctor Yellow

Monitor track conditions

and electrical

Order from JR

Operation Speed: 270km/h

Noise Level: 75dB(A)

Same as 700 Series

Two Pantograph: +3dB

Large Cover :+αdB

Noise Reduction:3-5dB

2014/6/30

21


40Flow Around a Large Cover

700 Series

Original Cover of Doctor Yellow

Noise Source Distribution

Noise Levels +4dB


41Simulations

2014/6/30

22

2011.09.28スズキ（浜松市）スズキ（浜松市）スズキ（浜松市）スズキ（浜松市）


Experiments :200 cases

Simulations :40 cases

Source Term


43

Blackhead

Noise Reduction Idea

Noise Level

-1dB

2014/6/30

23

Full 3D Simulation


44

Number of Elements 4Million


45Optimization

With Slope

Noise Level: -1dB (700 series)

Aerodynamic Performance : Same as the 700 series

Bulkhead

2014/6/30

24


46Summary

Some topics about aeroacoustic were shown:

・・・・Microphone array :Noise Source Distribution.

・・・・Curie's Theory ; Prediction Accuracy is high.

・・・・Correlation Length Model : Noise Reduction Idea

However, we should be used the theory of vortex sound to

understand the relationship between the noise and flow

Unsteady Vortices Motion : Real Noise Source

Time-resolved PIV : Noise Source Distribution

Vortex Sound Theory : Reduction Pantograph noise

Visualization of the sound source plays an important role in

the study of aerodynamic sound.


47Future Work (1)

Noise Control with Plasma Actuator

2014/6/30

25


48Noise Control


49Future Work (2)Coupling Analysis

Flow induced Vibration and Noise

Sound Field Simulation

FrontFlow/Blue-ACOUSTICS

Simulation of Structural Vibration

Adventure

Turbulence Simulation

FrontFlow/Blue

Interior Noise Simulation

FrontFlow/Blue-ACOUSTICS

Convert to Frequency

Domain

Mapping

Convert to Frequency

Domain

2014/6/30

26


50Aerodynamics Consortium


51Coupling Analysis

Data mapping

Flow Field Vibration

2014/6/30

27


52Flow Induced Vibration


53Scale of Computation

Flow Simulation：：：：Scale of the Smallest Eddy: 5mm (4kHz））））Length Scale of Boundary Layer:0.1 mm

Minimum Size Mesh: 200µµµµm

Number of Grids 20-50billion

Vibration Analysis：：：：Frequency of Induced Vibration : 4kHz

Degree of Freedom: 100million

Resolution: 1mm

Number of Grids: 10millon

Sound Analysis:Frequency of Interior Noise: 4kHz

Resolution: 3mm

Number of Grids: 1billion

2014/6/30

28


54Simulation of Music Instruments


55Simulation of Reed InstrumentsReed Vibration & Flow

2014/6/30

29


56Future Work (3)

Simulation of Noise Field around a Magic Pipe

Pipe and Bend Flow

Rotational Flow

Jet and Wake Flow

Noise from Low Mack Number Flow

Resonance (Oregano Pipe)

Acoustics Feedback (Cavity)

Self････Sustaining oscillations

Flow Induced Vibration

Structural Vibration

Deformation of Body (and Mesh)

Noise Transmit ion of thin Wall

The performance of super

computers are 1000 times

faster in each 10 years

Documents

Identification of Aerodynamic Sound Source of Industrial ...aero.me.tut.ac.jp/ISFV2014.pdf · 2014/6/30 1 ISFV2014 (Okinawa) 2014.06.26 0 Identification of Aerodynamic Sound Source