Noise Source Identification and Noise Directivity Analysis

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Publications of the Ray W. Herrick Laboratories School of Mechanical Engineering

7-2020

Noise Source Identification and Noise Directivity Analysis of Noise Source Identification and Noise Directivity Analysis of

Bladeless Fans by Combined CFD and CAA Method Bladeless Fans by Combined CFD and CAA Method

Ang Li Purdue University, [email protected]

Jun Chen Purdue University

Yangfan Liu Purdue University

J Stuart Bolton Purdue University, [email protected]

Patricia Davies Purdue University

Follow this and additional works at: https://docs.lib.purdue.edu/herrick

Li, Ang; Chen, Jun; Liu, Yangfan; Bolton, J Stuart; and Davies, Patricia, "Noise Source Identification and Noise Directivity Analysis of Bladeless Fans by Combined CFD and CAA Method" (2020). Publications of the Ray W. Herrick Laboratories. Paper 232. https://docs.lib.purdue.edu/herrick/232

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Influence of Geometric Parameters on Aerodynamic

and Aeroacoustic Performance of Bladeless Fans

Ang Li, Jun Chen, Yangfan Liu,

Stuart Bolton, Patricia Davies

Ray W. Herrick Laboratories

Purdue University

West Lafayette, 47907, USA

August 1st, 2019

AJKFLUIDS 2019-5220 07.28-08.01 San Francisco, CA, USA

https://07.28-08.01

OUTLINE

⚫ Background & Motivation

⚫ Methodology

➢ Experiments

➢ Numerical Simulations

⚫ Results

⚫ Conclusions

2AJKFLUIDS 2019-522007.28 - 08.01, 2019, San Francisco, CA, USA

BACKGROUND: FANS IN INDUSTRY

Vehicle Engine CPU Radiator Fan

HVAC Cooling Fan

Applications

– Cooling system

– Ventilation

– Thermal comfort

Features

– High flow rate

– Low noise level

07.28 - 08.01, 2019, San Francisco, CA, USA AJKFLUIDS 2019-5220 3

Wind channel

airfoil

... ,,.,.,.~ impeller

Step2-0utlet ai,·

" r

St~pS- lnM & Outlet ai,·

r Base

Step3- Suctioned air Step4- Eotraimuent

©

BLADELESS FAN

• Bladeless fans launched by Dyson

Working mechanism of the bladeless fan

Advantages Jafari et al. (2015)

– The produced wind is softer and more uniform.

– Flow rate at downstream is larger.

– No visible rotating blade is safer for children.


AN EXAMPLE OF THE BLADELESS FAN

– UK, Dyson. “Dyson Cool Fans - Air Multiplier Technology Explained - Official Video.” YouTube, YouTube, 5 Mar. 2014, www.youtube.com/watch?v=bUJ-X1rsKV4.


www.youtube.com/watch?v=bUJ-X1rsKV4

PREVIOUS WORK

Flow field structure outside the bladeless fan over the center plane

Li et al. (2016) Li et al. (2014)

Curve 1 Prototype Curve 4

Pressure (Pa)

Curve 2 Curve 3 Curve 5

Pressure distribution near the slit with different Coanda surface curvatures

Jafari et al. (2015) Jafari et al. (2016) Jafari et al. (2016)

. Power Level (d B) Surface Acoustic

38 30 ll IJ 5

(a)

"' :; 0::

"' 0

i.:

" s = 0 > " .:: =

0

2500

OT=2mm OT=3mm

....... ~60;;-- 18100 10 20 4° Flow Rate (L/s) Inlet Volume

400 350 300 250 200 150 100 50 0

-50 -100 -150

Streamlines outside the bladeless fan over the center plane

Sound power contour Effect of the outlet thickness and outlet angle on volume flow rate at downstream


OBJECTIVE & RESEARCH STRATEGY

▪ Characterize the aerodynamic and aeroacoustic performances of the

bladeless fan by a combined 3D numerical and experimental study

▪ Investigate the influence of geometric parameters of the wind channel

on bladeless fan’s performance

707.28 - 08.01, 2019, San Francisco, CA, USA AJKFLUIDS 2019-5220

Bladeless fan Prototype

Experiments Numerical Simulations

c

H

Influence of the geometric parameters of the wind channel

x0

METHODOLOGY: VELOCITY MEASUREMENT AT FAR FIELD

Measurement in Herrick PBE Lab

– Measurement position: 837

– Measurement duration at each position: 30s

– Sampling rate: 1s

– Accuracy: ±(2%+0.03m/s of indicated values)

X velocity contour

3D ultrasonic anemometer 0.8m

@x = 1.5m


yz

x

x = 1.5m

X velocity component(m/s)

3.4 3.2 3 2.8 2.6 2.4 2.2 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0

8

--

• • -+ -+ -+

METHODOLOGY: SOUND PRESSURE MEASUREMENT AT RECEIVERS

Measurement in Herrick anechoic chamber

x = 1.5m

Receiver 1

z = 0.8m

z

x = 0.1m

Receiver 2

B&K intensity probe

Sound pressure level @ two receivers

x

70 cu a.. ::i.

0 -- Receiver 1 N 60 II -- Receiver 2 -~

50 Cl.

Ill "O 40 -Q) > Q) 30 Q) "-::J Cf) 20 Cf) Q) "-Cl.

"O 10 C ::J 0

Cf) 0 0 1000 2000 3000 4000 5000

Frequency (Hz)


2m

Mass flow rate ---

PROTOTYPE OF THE BLADELESS FAN

H

x0

c

d=2mm, H=3cm, c=12cm, x0/c=10%

Cross-section of the wind channel

Qinlet

= 0.11kg/s

Computational domain

Temperature: 25℃~ 30℃ Reynolds number at the intake and the slit: 𝐑𝐞𝐢𝐧𝐭𝐚𝐤𝐞 = 𝟔𝟕𝟐𝟑,𝐑𝐞𝐬𝐥𝐢𝐭 = 𝟑𝟎𝟎𝟎~𝟒𝟏𝟎𝟎

Blocks at slit

10cm

Wind channel

Simulation Set-up

– The number of grids: 6,320,000

– Steady RANS: 𝒌 − 𝜺 model

– LES: Smagorinsky-Lilly model

– Time step: 𝟏 × 𝟏𝟎−𝟒 s

– Flow solver: SIMPLE


~· ,--,◄ .. .,...___ :

I I I I I I I I I I

~

x = 1.5m

x y

z z

centerline

2.0

1.5

N

= 9,680,000

- '1 2 3

W ise velocity (m/s) Stream

4

MESH GENERATION OF THE BLADELESS FAN

– Mesh independency test

• Mesh for the computational domain • Mesh for the cross-section of the wind channel

𝒚+ = 𝟎. 𝟖𝟓


METHODOLOGY: DATA POSTPROCESSING

Power spectral density of sound

pressure

Sound pressure

level

Acoustics Analysis

(Solver: Matlab)

Aeroacoustic

results

Unsteady Flow

Simulation + BC & IC

(Solver: OpenFoam)

'( , )p tx

(FW-H analogy)

Aeroadynamic results


X Velocity

5 4.8 4.6 4.4 4.2 4 3.8 3.6 3.4 3.2 3 2.8 2.6 2.4 2.2 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0

RESULTS: INSTANTANEOUS FLOW FIELD

z = 0.8m ⚫ X velocity over Z planes

⚫ LES, t = 5s to 15s

z = 0.55m z = 0.3m


Mean X Velocity: o 0.2 0.4 o.6 0.0 1 1.2 1.4 1.6 1.0 2 2.2 2.4 2.6 2.0 3 3.2 3.4

Ill

-· I I ...... I I ...... I I I ...... I I I

~

1.4

1.2

1.0

Io.a N

0.6

-Exp. ------ RANS

· - · LES

~

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

X velocity (m/s)

@ X=1.5 m

LES, time-averaged RANS Exp.

(t = 4s to 15s)

x = 1.5m

x ycenterline


@ z = 0.8m

@ the center plane of the bladeless fan

z z

z

AERODYNAMIC CHARACTERISTICS: MEAN FLOW

r

' \

\ \

3 2 1 0

-1 -2 -3 -4 -5 -6 -7 -8 -9 -10

AERODYNAMIC CHARACTERISTICS: MEAN PRESSURE

z = 0.8m ⚫ Pressure over Z planes

⚫ LES, averaged from t=4s to 15s

Pressure (Pa)

z = 0.55m z = 0.3m


~

X = 0.1m x= 0.5m x= 1.5m

-- die = 1.25% -- die= 1.67% -- die= 2.08% -- die= 2.50%

X ---►

0.4

0.2

E ___. 0.0 >-

-0.2

-0.4

U/ Uinlet 0.0 0.4 0.8 1.2

0 2 3 ux (m/s)

1.6

4

3.34

1.67

(.) 0.00 >=

-1.67

EFFECT OF THE SLIT WIDTH

LES, time averaged for t = 4s to 15s, @ x =1.5 m

Slit Width

c = 12cm

d/c = 1.25% d/c = 1.67% (baseline) d/c = 2.08% d/c = 2.50%

@ z = 0.8m


(!! ~

~

~ I

I I I I I :

I f x=0.1m

X velocity component(m/s) o 0.2 o.4 o.6 0.0 1 1.2 1.4 1.6 1.0 2 2.2 2.4 2.6 2.0 3 3.2 3.4

--Hie= 16.7% -- Hie= 25.0%

x= 0.5m x= 1.5m -- Hie= 33.3% --Hie= 41 .7%

X

u / u inlet 0~ 0.4 0.8 1.2

0.4

0.2

_s 0.0

>--0 .2 +---+--

-0.4

0 2 3

u x (m/s)

1.6

4

3.34

1.67

(.) 0.00 >=

-1.67

-3.34

EFFECT OF THE CROSS-SECTION HEIGHT

LES, time averaged for t = 4s to 15s, @ x =1.5 mH = 2cm

H = 3cm

H = 4cm

H = 5cm H/c = 16.7% H/c = 25.0% (baseline) H/c = 33.3% H/c = 41.7%

c = 12cm

@ z = 0.8m



--x0/c=5% U/ Uinlet --x0/c=1 0% 0.0 0.4 0.8 1.2 1.6

--x0/c=15% ' X = 1.5m 0.4 ' 3.34 ,-X = 0.1m x= 0.5m --x0/c=20%

0.2 1.67 _,,,,. ,....._ E '- (..) - 0.0 \\ 0.00 ;;::: >- ,.,··

X -0.2 -1.67

---►

-0.4 -3.34

0 2 3 4

ux (m/s)

EFFECT OF THE SLIT LOCATION

LES, time averaged for t = 4s to 15s, @ x =1.5 m

𝒙𝟎/c = 5% 𝒙𝟎/c = 10% (baseline) 𝒙𝟎/c = 15% 𝒙𝟎/c = 20%

c = 12cm

@ z = 0.8m


x0 = 0.6cm

x0 = 1.2cm

x0 = 1.8cm

x0 = 2.4cm

~

x=0.1m


- NACA0015 - Baseline

x= 0.5m x=15m - CLARK YM-15 - EPPLER478 0.4

0.2

-----S 0.0 >-

X ---►

-0.2

-0.4

0.0

I " I ·,

U/ Uinlet 0.4 0.8 1 2

·- . ----

1.6

t

· , , -...: !,..__

+ , - \ ::,. ✓. - : ::--·

3.34

1.67

(.) 0 .00 >=

---· ---- -1 .67 .,, I

----+------+------< -3.34

0 2 3 4

ux (m/s)

EFFECT OF THE PROFILE OF CROSS-SECTION

NACA 0015 LES, time averaged for t = 4s to 15s, @ x =1.5 m

CLARK YM-15

EPPLER 478

Baseline NACA0015 CLARK YM-15 EPPLER 478 Baseline

@ z = 0.8m


' ' ' -

- i Qtotal

5

14 M-1T -e- M2 4

.---.. .---.. + ~ 12 .._, ~

~ 3~

::f 10 ~-•T! 2

8 +--:,~,-,---,-~,--..----,--~-~_J 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.~

die(%)

5

+ 14 ~

4

~12 0

~ -:-----· 3 ~

10 /I ~ 2 I

8 1 5 10 15 20

x0/c (%)

.---.. ~ 0 .._, ~N

,----,----,--------.--- 5

14 :_~ -,,.-------+-J---

- - M2 4

.---.. ~ 12 0 .._,

~ 10 +t 2

8+---,----~----_J 1 20 30 40

Hie(%)

5 14 - M1

12 - M2 4

.---.. ~ 8 0 .._,

3 .---.. ~ 0

~ 6 2 ? 4

1 2

0 CLARK YM-15 EPPLER 478 Baseline

Profile of cross-section

RATIO OF MASS FLOW RATE

Effect of slit width Effect of cross-section height

Effect of slit location

𝑄𝑡𝑜𝑡𝑎𝑙 𝑀1 =

𝑄𝑖𝑛𝑙𝑒𝑡

𝑄𝑏𝑎𝑐𝑘 𝑀2 =

𝑄𝑖𝑛𝑙𝑒𝑡


Effect of profile of the cross-section

20

~ 70 ro a.. ::t

0 60 N .. • • II

I!! 50 a.

co :s, 40 .. Q) > ~ 30 ~ :::J .. rJ) 20 rJ) Q)

c.. "O 10 C :::J 0 0 Cl)

~ 70 ro a.. ::t

0 60 N

II

J 50

co :s, 40 Q) > ~ 30 Q) .... :::J rJ) 20 rJ) Q) .... a.

"O 10 C :::J 0

Cl)

0

Experimental result Numerical result

- - Boundary of 95%-confidence interval

1000 2000 3000 4000 5000

Frequency(Hz)

-- Experimental result -- Numerical result

- - Boundary of 95%-confidence interval

1000 2000 3000 4000

Frequency (Hz)

5000

AEROACOUSTIC CHARACTERISTICS

x = 1.5m

Receiver 1

z = 0.8m

z

x

x = 0.1m

Receiver 2

Sound pressure level @ x = 0.1m

@ x = 1.5m

– Acoustic model: FW – H model

– Density: 𝟏. 𝟐𝟐𝟓𝐤𝐠/𝐦𝟑

– Sound speed: 𝟑𝟒𝟎𝐦/𝐬 – Reference acoustic pressure: 𝟐𝟎𝛍𝐏𝐚 – Noise source: Bladeless fan


~ I /

~ =====================~

•

ro 30 a.. :::1.

0 <;'c_ 20

!"

~ 10 ~ :2, 0 ai ~ -10 Q)

~ -20 (/)

~-30 "O

§ -40 0

Cf)

ro 30 a..

:::1.

~ 20 IL

!"

~ 10 <( [D

:2, 0 ai ~ -10 l!? ~ -20 (/)

l!? ~-30 C ~

0

-- dlc=1 .25% --d/c=1.67% -- d/c=2.08% -- d/c=2.50%

1000 2000 3000 4000 5000

Frequency (Hz)

--+------4-----< -- x0 /c=5% --x0 /c=10%

--x0 /c=15%

--x0 /c=20%

~-40+------,----+----+---~--o 1000 2000 3000 4000 5000

Frequency (Hz)

H/c=16.7% -- H/c=25.0%

H/c=33.3% H/c=41 .7%

1000 2000 3000 4000 5000

Frequency (Hz)

ro ~ 20 - :;_"rj~~~:ia;;:~ 7-----t---o N

I~ 10 0.

'

~ -10 ~

~ -20 (/) (/)

~ -30 "O C

-Baseline - NACA0015 - CLARK YM-15 - EPPLER478

i5 -40+------~-----~--(/) 0 1000 2000 3000 4000 5000

Frequency (Hz)

Receiver

z = 0.8m

z

x

EFFECT OF THE GEOMETRIC PARAMETERS ON AEROACOUSTIC PERFORMANCE

H

x0

c

Effect of slit width Effect of cross-section height

d=2mm, H=3cm, c=12cm, x0/c=10%

x = 1.5m Effect of slit location Effect of profile of the cross-section


CONCLUSIONS

— When the wind produced by the bladeless fan becomes more

powerful, the aerodynamic noise is louder.

— With the decrease of the slit width, the wind strength becomes

more powerful. The generated noise increases at the same time.

— The bladeless fan with the cross-section of 4cm has the best

aerodynamic performance, but the generated noise is the

loudest.

— With the slit moves away from the leading edge, both wind

strength and noise level increase.

— The profile of the cross-section affect the shape of the influence

zone, but has insignificant effect on outflow mass flow rate and

the generated noise.


ONGOING EFFORT

— Investigate the performance of the bladeless fan prototype with

the impeller in the base

— Identify the main noise source

— Analyze the noise directivity of the bladeless fan

— Come up with a general criteria to evaluate the aerodynamic

performance of the bladeless fan (i.e. strength, uniformity and

steadiness of the wind)

— Propose a criteria to evaluate the compromise between the

aerodynamic and aeroacoustic performance

— Apply the results to optimize the design of the new-generation

bladeless fan.


Glidea

ACKNOWLEDGEMENT

• Thanks to the financial support and professional feedback

provided by Midea Global Innovation Center


Documents

Noise Source Identification and Noise Directivity Analysis