國立虎尾科技大學 |

Experimental Investigation of the Unsteady Noise Sources Generated by a UAM Rotor in Forward Flight.

紀錄類型:	書目-語言資料,手稿 : Monograph/item
正題名/作者:	Experimental Investigation of the Unsteady Noise Sources Generated by a UAM Rotor in Forward Flight./
作者:	Goldschmidt, James D.
面頁冊數:	1 online resource (227 pages)
附註:	Source: Dissertations Abstracts International, Volume: 85-04, Section: B.
Contained By:	Dissertations Abstracts International85-04B.
標題:	Fluid mechanics. -
電子資源:	click for full text (PQDT)
ISBN:	9798380606837

Experimental Investigation of the Unsteady Noise Sources Generated by a UAM Rotor in Forward Flight.
Goldschmidt, James D.

Experimental Investigation of the Unsteady Noise Sources Generated by a UAM Rotor in Forward Flight. - 1 online resource (227 pages)

Source: Dissertations Abstracts International, Volume: 85-04, Section: B.

Thesis (Ph.D.)--University of Florida, 2023.

Includes bibliographical references

The future of Urban Air Mobility (UAM) presents a promising reality, where daily large-scale air taxi operations will be achieved using electric vertical take-off and landing vehicles (eVTOL). UAM rotors have fixed-pitch blades and operate with low tip speeds, so that the noise they produce is dominated by tonal unsteady loading and broadband noise sources. The goal of the experiments in this study was to reveal physical reasoning's for the force and noise trends seen in these new rotor flight conditions.Experiments were performed on a proposed fixed wing eVTOL configuration, including a two-blade lifting and five-blade tilting rotor, both independently and in tandem with and without installation hardware. Simultaneous rotor force and far field noise measurements were obtained in the University of Florida Anechoic Wind Tunnel facility. The single rotor results showed that the forces were a function of the edgewise advance ratio. The tonal noise indicated an unsteady loading noise source. While, the broadband sources were blade wake interaction noise for frequencies below 30 blade pass frequency harmonics and trailing edge noise above 30 blade pass frequency harmonics. The magnitude and priority of these broadband noise sources also varied with edgewise advance ratio. The overall sound pressure level of the lift rotor was dominated by tonal noise and the tilt rotor was dominated by broadband noise.The isolated tandem rotor configuration produced force trends which were similar to the single rotor experiments, with the lift rotor forces also being dependent on the path of the tilt rotor wake. The wing and boom altered the forces with respect to the isolated configuration. The isolated tandem rotor noise had similar trends to the single rotor experiments, with the possibility of additional blade vortex interaction noise. The overall sound pressure level of the tandem rotor configuration was dominated by the lift rotor tonal noise.Based on the observed noise trends, stereoscopic Particle Image Velocimetry was employed to measure the inflow and wake velocities of a single two-blade rotor in edgewise flight. The inflow measurements were used for unsteady force modeling and analytical tonal blade pass frequency noise predictions, which were accurate to +/- 2 dB below the rotor plane. The wake measurements revealed an asymmetric distribution of wake vorticity, with greater advancing side levels than retreating side levels. Proper Orthogonal Decomposition analysis of the wake revealed coherent turbulent structures, which are key to the rotor wake decay.A two-blade rotor was analyzed in edgewise flight using both clean and turbulent freestream flow conditions. The turbulence had minimal effects on rotor noise, but acted to reduce rotor efficiency. Through stereoscopic Particle Image Velocimetry, it was found that the rotor distorted the freestream turbulence creating a non-homogeneous field with elevated levels on the downstream edge of the rotor disk.

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

Mode of access: World Wide Web

ISBN: 9798380606837Subjects--Topical Terms:

555551
Fluid mechanics.
Subjects--Index Terms:

Fluid-dynamicsIndex Terms--Genre/Form:

554714
Electronic books.

Experimental Investigation of the Unsteady Noise Sources Generated by a UAM Rotor in Forward Flight.
LDR:04373ntm a22003977 4500 001 1145153
005 20240617111357.5
006 m o d
007 cr mn ---uuuuu
008 250605s2023 xx obm 000 0 eng d
020 $a 9798380606837
035 $a (MiAaPQ)AAI30575268
035 $a AAI30575268
040 $a MiAaPQ $b eng $c MiAaPQ $d NTU
100 1 $a Goldschmidt, James D. $3 1470380
245 1 0 $a Experimental Investigation of the Unsteady Noise Sources Generated by a UAM Rotor in Forward Flight.
264 0 $c 2023
300 $a 1 online resource (227 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: Dissertations Abstracts International, Volume: 85-04, Section: B.
500 $a Advisor: Ukeiley, Lawrence.
502 $a Thesis (Ph.D.)--University of Florida, 2023.
504 $a Includes bibliographical references
520 $a The future of Urban Air Mobility (UAM) presents a promising reality, where daily large-scale air taxi operations will be achieved using electric vertical take-off and landing vehicles (eVTOL). UAM rotors have fixed-pitch blades and operate with low tip speeds, so that the noise they produce is dominated by tonal unsteady loading and broadband noise sources. The goal of the experiments in this study was to reveal physical reasoning's for the force and noise trends seen in these new rotor flight conditions.Experiments were performed on a proposed fixed wing eVTOL configuration, including a two-blade lifting and five-blade tilting rotor, both independently and in tandem with and without installation hardware. Simultaneous rotor force and far field noise measurements were obtained in the University of Florida Anechoic Wind Tunnel facility. The single rotor results showed that the forces were a function of the edgewise advance ratio. The tonal noise indicated an unsteady loading noise source. While, the broadband sources were blade wake interaction noise for frequencies below 30 blade pass frequency harmonics and trailing edge noise above 30 blade pass frequency harmonics. The magnitude and priority of these broadband noise sources also varied with edgewise advance ratio. The overall sound pressure level of the lift rotor was dominated by tonal noise and the tilt rotor was dominated by broadband noise.The isolated tandem rotor configuration produced force trends which were similar to the single rotor experiments, with the lift rotor forces also being dependent on the path of the tilt rotor wake. The wing and boom altered the forces with respect to the isolated configuration. The isolated tandem rotor noise had similar trends to the single rotor experiments, with the possibility of additional blade vortex interaction noise. The overall sound pressure level of the tandem rotor configuration was dominated by the lift rotor tonal noise.Based on the observed noise trends, stereoscopic Particle Image Velocimetry was employed to measure the inflow and wake velocities of a single two-blade rotor in edgewise flight. The inflow measurements were used for unsteady force modeling and analytical tonal blade pass frequency noise predictions, which were accurate to +/- 2 dB below the rotor plane. The wake measurements revealed an asymmetric distribution of wake vorticity, with greater advancing side levels than retreating side levels. Proper Orthogonal Decomposition analysis of the wake revealed coherent turbulent structures, which are key to the rotor wake decay.A two-blade rotor was analyzed in edgewise flight using both clean and turbulent freestream flow conditions. The turbulence had minimal effects on rotor noise, but acted to reduce rotor efficiency. Through stereoscopic Particle Image Velocimetry, it was found that the rotor distorted the freestream turbulence creating a non-homogeneous field with elevated levels on the downstream edge of the rotor disk.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2024
538 $a Mode of access: World Wide Web
650 4 $a Fluid mechanics. $3 555551
650 4 $a Acoustics. $3 670692
650 4 $a Aerospace engineering. $3 686400
653 $a Fluid-dynamics
653 $a Rotor
653 $a Turbulence
653 $a Urban Air Mobility
653 $a Rotor disk
655 7 $a Electronic books. $2 local $3 554714
690 $a 0538
690 $a 0986
690 $a 0204
710 2 $a University of Florida. $b Aerospace Engineering. $3 1470381
710 2 $a ProQuest Information and Learning Co. $3 1178819
773 0 $t Dissertations Abstracts International $g 85-04B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30575268 $z click for full text (PQDT)