國立虎尾科技大學 |

Advanced Experimental Techniques for High Resolution Detection of Aft-Emitted Tonal Fan Noise.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Advanced Experimental Techniques for High Resolution Detection of Aft-Emitted Tonal Fan Noise./
Author:	Miller, Kyle.
Description:	1 online resource (79 pages)
Notes:	Source: Masters Abstracts International, Volume: 85-02.
Contained By:	Masters Abstracts International85-02.
Subject:	Acoustics. -
Online resource:	click for full text (PQDT)
ISBN:	9798380127264

Advanced Experimental Techniques for High Resolution Detection of Aft-Emitted Tonal Fan Noise.
Miller, Kyle.

Advanced Experimental Techniques for High Resolution Detection of Aft-Emitted Tonal Fan Noise. - 1 online resource (79 pages)

Source: Masters Abstracts International, Volume: 85-02.

Thesis (M.S.)--University of California, Irvine, 2023.

Includes bibliographical references

The near acoustic field of a subscale ducted fan was experimentally measured for the purpose of understanding the physics of sound generation and refining low-order models for aft-emitted tonal fan noise. To properly resolve the detailed features of the pressure field, measurements were obtained using a phased microphone array comprising of fixed and scanning sensors. The traversing of a sensor through a spatially-varying acoustic field introduces signal non-stationarity which must be addressed by dividing the complete signal into quasistationary blocks and applying a frequency-dependent window during spectral estimation. The harmonic content of the pressure along the scan line was obtained from the signals of the axially scanning sensors using the Vold-Kalman (VK) filter and partial fields decomposition (PFD). Accurate construction of the axial pressure distribution from the microphone measurements required advanced interpolation and filtering techniques based on the the decomposition of the pressure into its unwrapped phase and amplitude. The resulting axial pressure field has sufficient spatial resolution to perform space-time correlations and calculate the convective Mach number distribution. The azimuthal distribution of the tonal pressure field was obtained from the fixed sensors using the VK filter and can be combined with the axial pressure distribution to generate a cylindrical radiation surface. The radiation surface can then be implemented into propagation and scattering tools, such as the boundary element method (BEM), to efficiently predict acoustic emission in isolated and installed configurations. The near-field measurements are compared to the predictions of a model for aft tonal emission where the source features are partially informed by the internal duct acoustics. Reasonable agreement is found in the axial pressure distributions and space-time correlations. The near-field measurements can provide guidance for refinement of the model.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798380127264Subjects--Topical Terms:

670692
Acoustics.
Subjects--Index Terms:

Ducted fanIndex Terms--Genre/Form:

554714
Electronic books.

Advanced Experimental Techniques for High Resolution Detection of Aft-Emitted Tonal Fan Noise.
LDR:03345ntm a22003977 4500 001 1145121
005 20240617111349.5
006 m o d
007 cr mn ---uuuuu
008 250605s2023 xx obm 000 0 eng d
020 $a 9798380127264
035 $a (MiAaPQ)AAI30526823
035 $a AAI30526823
040 $a MiAaPQ $b eng $c MiAaPQ $d NTU
100 1 $a Miller, Kyle. $3 1470340
245 1 0 $a Advanced Experimental Techniques for High Resolution Detection of Aft-Emitted Tonal Fan Noise.
264 0 $c 2023
300 $a 1 online resource (79 pages)
336 $a text $b txt $2 rdacontent
337 $a computer $b c $2 rdamedia
338 $a online resource $b cr $2 rdacarrier
500 $a Source: Masters Abstracts International, Volume: 85-02.
500 $a Advisor: Papamoschou, Dimitri.
502 $a Thesis (M.S.)--University of California, Irvine, 2023.
504 $a Includes bibliographical references
520 $a The near acoustic field of a subscale ducted fan was experimentally measured for the purpose of understanding the physics of sound generation and refining low-order models for aft-emitted tonal fan noise. To properly resolve the detailed features of the pressure field, measurements were obtained using a phased microphone array comprising of fixed and scanning sensors. The traversing of a sensor through a spatially-varying acoustic field introduces signal non-stationarity which must be addressed by dividing the complete signal into quasistationary blocks and applying a frequency-dependent window during spectral estimation. The harmonic content of the pressure along the scan line was obtained from the signals of the axially scanning sensors using the Vold-Kalman (VK) filter and partial fields decomposition (PFD). Accurate construction of the axial pressure distribution from the microphone measurements required advanced interpolation and filtering techniques based on the the decomposition of the pressure into its unwrapped phase and amplitude. The resulting axial pressure field has sufficient spatial resolution to perform space-time correlations and calculate the convective Mach number distribution. The azimuthal distribution of the tonal pressure field was obtained from the fixed sensors using the VK filter and can be combined with the axial pressure distribution to generate a cylindrical radiation surface. The radiation surface can then be implemented into propagation and scattering tools, such as the boundary element method (BEM), to efficiently predict acoustic emission in isolated and installed configurations. The near-field measurements are compared to the predictions of a model for aft tonal emission where the source features are partially informed by the internal duct acoustics. Reasonable agreement is found in the axial pressure distributions and space-time correlations. The near-field measurements can provide guidance for refinement of the model.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2024
538 $a Mode of access: World Wide Web
650 4 $a Acoustics. $3 670692
650 4 $a Fluid mechanics. $3 555551
650 4 $a Aerospace engineering. $3 686400
650 4 $a Mechanical engineering. $3 557493
653 $a Ducted fan
653 $a Tonal fan noise
653 $a Acoustic emission
653 $a Vold-Kalman
655 7 $a Electronic books. $2 local $3 554714
690 $a 0986
690 $a 0204
690 $a 0538
690 $a 0548
710 2 $a ProQuest Information and Learning Co. $3 1178819
710 2 $a University of California, Irvine. $b Mechanical and Aerospace Engineering. $3 1180333
773 0 $t Masters Abstracts International $g 85-02.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30526823 $z click for full text (PQDT)