Post on 20-Mar-2020
Actran Users’ Conference 2012 October 3-4, 2012 - Brussels, Belgium
Aero-Acoustics Analysis in Vacuum Cleaner
Jongsoo Kim, Kitak Hyun
LG Electronics / Home Appliance Lab.
Daeyong Kim
Actran Users’ Conference 2012
Outline
Object and Approach
Actran Model - Full
- Muffler part
Transfer admittance
Unit Excitation - Nozzle and only pipe
- Directivity
- Sample Porous Material
Muffler part analysis - Transfer Admittance
- Using Microphone Measurement data
- Reciprocity Analysis
Aero-Acoustics - With CFD result
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(1) Aero-Acoustics of Motor Part
(2) Aero Acoustics Chamber Ass`y
(3) Fluid Flow Chamber
(4) Sym/Un-sym Chamber Ass`y
(1) Cyclone Optimization
(2) Optimize Separation Pipe Cyclone
(1) Aero Acoustics of Muffler
2. Muffler & Nozzle
(2) Muffler optimize
(3) Air Jet nozzle
(4) Muffler Drop & Impact
1. Motor & Chamber
3. Cyclone
■ Neck point
-. Reduce Noise Level and maintain Suction Power
-. Structural Vibration < Aero-Acoustics, Tran. Loss
Acoustics in VC
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Object & Approach
Reduce the noise level with muffler on VC
- 60dB -> 53dB
Calculation with Modal duct(Porous & Perforate duct)
Material tuning
Calculation with CFD Results
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ACTRAN Model
Directivity Field Point
Vertical Map Field Mesh
Experimental Field Point Position
Upper Silencer
Lower Silencer Infinite Element
Plane Wave Source
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ACTRAN Model #2
Porous Part (air)
Perforate inside Shell
Perforate outside Shell
Porous Solid Part
( or AIR ) Air Solid Part
Muffler part modeling strategy for perforated duct and porous(or air domain)
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Muffler Model(Section View)
surf 1
surf 2
Outside
surface
Inside
surface
Section View Separate the mesh with thickness of shell
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Transfer Admittance Table with in-house code (Mechel function)
d
2a
l
0
116 1
2
22
p
p
lR f
a
X f l l
In house code for generating ACTRAN Table file Admittance Plot
1 1
2 2
p pn
p pn
A Av p
A Av p
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Modal Duct Excitation(check Lower Muffler)
Modal duct region
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Radiation Power
Compare with Lower Nozzle or not
Nozzle muffler
Nozzle part don’t have a good performance for noise reduction of total system
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With and without Sample Porous
This is not real performance of VC, It’s only pattern Also, the porous material is ACTRAN sample file
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Time domain Source
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Focus on Upper part Muffler(TL)
Muffler hole Case Study
The excitation of this case is a modal duct for checking of performance
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Thank you for ACTRAN input dect
Input dect : Change the file name for Another mechel function
Make a batch file for running the case study during the night
Researcher can go home and check the results for all case on the next morning
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Case Study with Mechel Function modal duct excitation
Pitch
(Peak b
igger b
ut B
and R
educe
Hole Bigger Hole move to High Frequency
2: 28.376 (1) 1: 25.297 (2) 3: 26.740
4: 29.234 6: 31.488
7: 31.492(4) 9: 40.815
5: 36.549
8: 34.836 (3)
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Check with RSM
• dB(A) Relation Area & Contact Area
Relation
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Contact Area with Porous Part
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Radiation Source with measurement with real source
Check the source level with simple measurement on simple pipe of VC
Radiation Level dB(A)
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Convert Source for Input Reciprocity
dB(A) - dB -> Amplitude Pressure convert ( input )
Yellow: Measurement, Blue : CAE
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Compare Measurement and ACTRAN
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Contour Result
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Compare with another data
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Contour Result
1000Hz 2000Hz 3000Hz 4000Hz 5000Hz
No Porous
Porous
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Material tuning
We don’t know the material property of porous(sponge)
We have real source on inlet with reciprocity analysis
We can compare with the measurement and CAE result
in trial and error for material.
Solving time of the muffler case is so fast, then we can
analysis for material tuning job.
we can check the difference of the changed material of
muffler.
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Initial 9 Case Analysis
25
(BLUE : No Porous, RED : Porous ) Insertion Loss (with Porous), Case 3, Case 4 is more good performance.
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Insertion Loss
26
dB dB(A) AREA
Case1 37.30 36.47 8.80
Case 2 37.91 36.78 8.38
Case 3 50.70 49.94 14.72
Case 4 48.79 47.76 12.63
Case 5 30.15 29.22 2.47
Case 6 41.22 40.05 9.23
Case 7 42.20 41.39 8.00
Case 8 30.00 29.58 0.20
Case 9 35.16 34.07 1.88
영향도 Overall dB
No Porous dB – Porous dB
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Change the diameter of muffler for the lower frequency effect
If the muffler diameter is changed to bigger, the lower frequency have a good TL more than smaller
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Change Diameter (TL)
28
D1 < D2
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Conclusion
We can get Guide line for VC design with ACTRAN
CFD Result is very important to good result in ACTRAN
Porous Material Property is important to evaluate SPL
Need more study about porous material
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Thank you
Question