1 / 13 vibration analysis and noise reduction of the swinging unit magyar bálint (bme) a c r o b o...
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![Page 1: 1 / 13 Vibration analysis and noise reduction of the swinging unit Magyar Bálint (BME) A C R O B O T E R 3rd OSB meeting Reading, 22-23 / 11 / 2007 Vibration](https://reader036.vdocuments.site/reader036/viewer/2022081602/551a862a550346b52d8b58fe/html5/thumbnails/1.jpg)
1 / 13Vibration analysis and noise reduction of the swinging unitMagyar Bálint (BME)Magyar Bálint (BME)
A C R O B O T E R 3rd3rd OSB meeting OSB meeting Reading, Reading, 22-23 22-23 / / 1111 / 2007 / 2007
Vibration analysis and noise reduction of the swinging unit
![Page 2: 1 / 13 Vibration analysis and noise reduction of the swinging unit Magyar Bálint (BME) A C R O B O T E R 3rd OSB meeting Reading, 22-23 / 11 / 2007 Vibration](https://reader036.vdocuments.site/reader036/viewer/2022081602/551a862a550346b52d8b58fe/html5/thumbnails/2.jpg)
2 / 13Vibration analysis and noise reduction of the swinging unitMagyar Bálint (BME)Magyar Bálint (BME)
A C R O B O T E R 3rd3rd OSB meeting OSB meeting Reading, Reading, 22-23 22-23 / / 1111 / 2007 / 2007
Noise components of ducted fans
• Flow source Trace noise Noise of the turbulent boundary layer Noise of the separated flow region
• Mechanical source Noise of the drive train Noise of the excited cover Noise of the PWM control
![Page 3: 1 / 13 Vibration analysis and noise reduction of the swinging unit Magyar Bálint (BME) A C R O B O T E R 3rd OSB meeting Reading, 22-23 / 11 / 2007 Vibration](https://reader036.vdocuments.site/reader036/viewer/2022081602/551a862a550346b52d8b58fe/html5/thumbnails/3.jpg)
3 / 13Vibration analysis and noise reduction of the swinging unitMagyar Bálint (BME)Magyar Bálint (BME)
A C R O B O T E R 3rd3rd OSB meeting OSB meeting Reading, Reading, 22-23 22-23 / / 1111 / 2007 / 2007
Flow source noises
• Trace noise
• Noise of the turbulent boundary layer
0
0
drag
lifting
F
FS
![Page 4: 1 / 13 Vibration analysis and noise reduction of the swinging unit Magyar Bálint (BME) A C R O B O T E R 3rd OSB meeting Reading, 22-23 / 11 / 2007 Vibration](https://reader036.vdocuments.site/reader036/viewer/2022081602/551a862a550346b52d8b58fe/html5/thumbnails/4.jpg)
4 / 13Vibration analysis and noise reduction of the swinging unitMagyar Bálint (BME)Magyar Bálint (BME)
A C R O B O T E R 3rd3rd OSB meeting OSB meeting Reading, Reading, 22-23 22-23 / / 1111 / 2007 / 2007
Flow source noises
•Noise of the separated boundary layer
Proper and improper constructions for the entrance region
(1) Separation bubble (1) Laminar sublayer(2) Turbulent boundary
layer
![Page 5: 1 / 13 Vibration analysis and noise reduction of the swinging unit Magyar Bálint (BME) A C R O B O T E R 3rd OSB meeting Reading, 22-23 / 11 / 2007 Vibration](https://reader036.vdocuments.site/reader036/viewer/2022081602/551a862a550346b52d8b58fe/html5/thumbnails/5.jpg)
5 / 13Vibration analysis and noise reduction of the swinging unitMagyar Bálint (BME)Magyar Bálint (BME)
A C R O B O T E R 3rd3rd OSB meeting OSB meeting Reading, Reading, 22-23 22-23 / / 1111 / 2007 / 2007
Mechanical source noises
Finite element modal analysis
•DOF: 162168•N. of elements: 26824 •Solver: COSMOS
Mesh: Mode shape at 48.55 Hz:
![Page 6: 1 / 13 Vibration analysis and noise reduction of the swinging unit Magyar Bálint (BME) A C R O B O T E R 3rd OSB meeting Reading, 22-23 / 11 / 2007 Vibration](https://reader036.vdocuments.site/reader036/viewer/2022081602/551a862a550346b52d8b58fe/html5/thumbnails/6.jpg)
6 / 13Vibration analysis and noise reduction of the swinging unitMagyar Bálint (BME)Magyar Bálint (BME)
A C R O B O T E R 3rd3rd OSB meeting OSB meeting Reading, Reading, 22-23 22-23 / / 1111 / 2007 / 2007
Mechanical source noises
Results
Number of natural frequencies in each 20 Hz range
![Page 7: 1 / 13 Vibration analysis and noise reduction of the swinging unit Magyar Bálint (BME) A C R O B O T E R 3rd OSB meeting Reading, 22-23 / 11 / 2007 Vibration](https://reader036.vdocuments.site/reader036/viewer/2022081602/551a862a550346b52d8b58fe/html5/thumbnails/7.jpg)
7 / 13Vibration analysis and noise reduction of the swinging unitMagyar Bálint (BME)Magyar Bálint (BME)
A C R O B O T E R 3rd3rd OSB meeting OSB meeting Reading, Reading, 22-23 22-23 / / 1111 / 2007 / 2007
Measurement
• Four-channel-measurement 2 accelerometers microphone tachometer
![Page 8: 1 / 13 Vibration analysis and noise reduction of the swinging unit Magyar Bálint (BME) A C R O B O T E R 3rd OSB meeting Reading, 22-23 / 11 / 2007 Vibration](https://reader036.vdocuments.site/reader036/viewer/2022081602/551a862a550346b52d8b58fe/html5/thumbnails/8.jpg)
8 / 13Vibration analysis and noise reduction of the swinging unitMagyar Bálint (BME)Magyar Bálint (BME)
A C R O B O T E R 3rd3rd OSB meeting OSB meeting Reading, Reading, 22-23 22-23 / / 1111 / 2007 / 2007
Measurement
Zero pitch
Max pitch direction 1
Max pitchdirection 2
![Page 9: 1 / 13 Vibration analysis and noise reduction of the swinging unit Magyar Bálint (BME) A C R O B O T E R 3rd OSB meeting Reading, 22-23 / 11 / 2007 Vibration](https://reader036.vdocuments.site/reader036/viewer/2022081602/551a862a550346b52d8b58fe/html5/thumbnails/9.jpg)
9 / 13Vibration analysis and noise reduction of the swinging unitMagyar Bálint (BME)Magyar Bálint (BME)
A C R O B O T E R 3rd3rd OSB meeting OSB meeting Reading, Reading, 22-23 22-23 / / 1111 / 2007 / 2007
Waterfall diagrams
Microphone signal compared with finite element results
![Page 10: 1 / 13 Vibration analysis and noise reduction of the swinging unit Magyar Bálint (BME) A C R O B O T E R 3rd OSB meeting Reading, 22-23 / 11 / 2007 Vibration](https://reader036.vdocuments.site/reader036/viewer/2022081602/551a862a550346b52d8b58fe/html5/thumbnails/10.jpg)
10 / 13Vibration analysis and noise reduction of the swinging unitMagyar Bálint (BME)Magyar Bálint (BME)
A C R O B O T E R 3rd3rd OSB meeting OSB meeting Reading, Reading, 22-23 22-23 / / 1111 / 2007 / 2007
Waterfall diagrams
Microphone signal scaled by rpm
![Page 11: 1 / 13 Vibration analysis and noise reduction of the swinging unit Magyar Bálint (BME) A C R O B O T E R 3rd OSB meeting Reading, 22-23 / 11 / 2007 Vibration](https://reader036.vdocuments.site/reader036/viewer/2022081602/551a862a550346b52d8b58fe/html5/thumbnails/11.jpg)
11 / 13Vibration analysis and noise reduction of the swinging unitMagyar Bálint (BME)Magyar Bálint (BME)
A C R O B O T E R 3rd3rd OSB meeting OSB meeting Reading, Reading, 22-23 22-23 / / 1111 / 2007 / 2007
Waterfall diagrams
The 8 kHz PWM noise appearing in the signal of the 2nd accelerometer
![Page 12: 1 / 13 Vibration analysis and noise reduction of the swinging unit Magyar Bálint (BME) A C R O B O T E R 3rd OSB meeting Reading, 22-23 / 11 / 2007 Vibration](https://reader036.vdocuments.site/reader036/viewer/2022081602/551a862a550346b52d8b58fe/html5/thumbnails/12.jpg)
12 / 13Vibration analysis and noise reduction of the swinging unitMagyar Bálint (BME)Magyar Bálint (BME)
A C R O B O T E R 3rd3rd OSB meeting OSB meeting Reading, Reading, 22-23 22-23 / / 1111 / 2007 / 2007
The 8 kHz PWM noise appearing in the signal of the microphone
![Page 13: 1 / 13 Vibration analysis and noise reduction of the swinging unit Magyar Bálint (BME) A C R O B O T E R 3rd OSB meeting Reading, 22-23 / 11 / 2007 Vibration](https://reader036.vdocuments.site/reader036/viewer/2022081602/551a862a550346b52d8b58fe/html5/thumbnails/13.jpg)
13 / 13Vibration analysis and noise reduction of the swinging unitMagyar Bálint (BME)Magyar Bálint (BME)
A C R O B O T E R 3rd3rd OSB meeting OSB meeting Reading, Reading, 22-23 22-23 / / 1111 / 2007 / 2007
Conclusions
Reduction or elimination of noise components
• Flow source components Trace noise - Not significant Noise of the turbulent boundary layer - By choosing better airfoil Noise of the separated flow region - Proper contstruction of the
entrance region
• Mechanical source components Noise of the excited cover - By increasing stiffness, rarefying
natural frequencies Noise of the PWM control - By raising controller frequency
above human hearing limit
Estimated total possible noise reduction:dBALA 86