東華大學圖書館 |

Aeromechanics of a Double Anhedral Tip Composite Rotor : = Experiment and Modeling.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Aeromechanics of a Double Anhedral Tip Composite Rotor :/
其他題名:	Experiment and Modeling.
作者:	Chi, Cheng.
面頁冊數:	1 online resource (259 pages)
附註:	Source: Dissertations Abstracts International, Volume: 84-03, Section: B.
Contained By:	Dissertations Abstracts International84-03B.
標題:	Aerospace engineering. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29214553click for full text (PQDT)
ISBN:	9798351447162

Aeromechanics of a Double Anhedral Tip Composite Rotor : = Experiment and Modeling.
Chi, Cheng.

Aeromechanics of a Double Anhedral Tip Composite Rotor :Experiment and Modeling. - 1 online resource (259 pages)

Source: Dissertations Abstracts International, Volume: 84-03, Section: B.

Thesis (Ph.D.)--University of Maryland, College Park, 2022.

Includes bibliographical references

This thesis investigates the performance and loads on a double-anhedral tip modern composite rotor. Double anhedral tips are a recent introduction in rotors with no research data available for understanding their behavior or modeling them adequately. The objectives were to bridge these gaps. Both experimental and analytical methods were employed to fulfill the objectives systematically. Double anhedral blades of 5.6-ft diameter were designed and fabricated. The blades had a uniform VR-7 airfoil profile, a D-spar, −16◦ twist, a 5◦ dihedral from 80%R to 95%R and a 15◦ anhedral from 95%R to the tip. The blades were built in-house using IM7/8552 graphite/epoxy prepreg weave. They were instrumented for strains and structural loads measurement. A two-bladed hingeless hub was designed and fabricated for the vacuum chamber to measure rotating frequencies (fan plot). The hover tests were performed on the Alfred Gessow Rotorcraft Center Mach-scaled four-bladed hingeless rig. Tests were carried out up to tip Mach number of 0.6 over a collective range of 0◦ to 10◦ . The rotor performance, blade structural loads, pitch link loads, and surface strains were measured. A double anhedral tip is a 3-D structure. Accordingly, a 3-D model was developed with CATIA (CAD), Cubit (hexahedral meshing), and X3D (aeromechanics). The 3-D CAD was constructed with guidance from Boeing to ensure the geometry was representative of a modern rotor yet generic enough to be open source for U.S. Gov-industry-academia joint study. The meshing used 27-node solid hexahedral elements, as needed by X3D. The pitch bearing was modeled with a joint commanded by control input. In total there were 3427 elements and approximately 100,000 degrees of freedom. Properties of the composite plies were acquired through in-house four-point bending coupon tests. The aerodynamic model used in-house CFD extracted C-81 decks and a lifting line with a refined free wake. The data acquired from tests were used to validate the model. A 3-D model of a straight blade was also developed as a baseline for comparison. These models have the same external and internal structure except for the tip. By comparing the behavior of the analytical models, insights were gained on the impacts of a double anhedral tip on the structural dynamics and aeromechanics in hover and forward flight. The local center of gravity offset at the tip appeared to make the blade softer. No performance gain was predicted in hover, however, the static flap, lag, and torsion moments at the root all decreased due to the vertical center of gravity offset in the tip portion. Strong 3-D strain patterns and multiple strain concentrations at the tip were predicted. In forward flight, the 4/rev vibratory vertical hub load and hub moments were predicted to increase by 15% and 100% respectively at tip speed ratio 0.1. Higher 1/rev oscillatory flap bending moment and 2/rev oscillatory lag bending moments were also predicted. The key conclusion is that the vertical center of gravity of the double anhedral tip can have significant ramifications on blade loads - reducing the static loads while increasing oscillatory harmonics particularly vibratory harmonics in forward flight. Systematic wind-tunnel tests are needed in future to dissect these effects. This thesis laid the foundations of that future through blade fabrication, vacuum and hover testing.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798351447162Subjects--Topical Terms:

1002622
Aerospace engineering.
Subjects--Index Terms:

3-D modelingIndex Terms--Genre/Form:

542853
Electronic books.

Aeromechanics of a Double Anhedral Tip Composite Rotor : = Experiment and Modeling.
LDR:04767nmm a2200373K 4500 001 2354267
005 20230403071203.5
006 m o d
007 cr mn ---uuuuu
008 241011s2022 xx obm 000 0 eng d
020 $a 9798351447162
035 $a (MiAaPQ)AAI29214553
035 $a AAI29214553
040 $a MiAaPQ $b eng $c MiAaPQ $d NTU
100 1 $a Chi, Cheng. $3 3383056
245 1 0 $a Aeromechanics of a Double Anhedral Tip Composite Rotor : $b Experiment and Modeling.
264 0 $c 2022
300 $a 1 online resource (259 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: 84-03, Section: B.
500 $a Advisor: Datta, Anubhav.
502 $a Thesis (Ph.D.)--University of Maryland, College Park, 2022.
504 $a Includes bibliographical references
520 $a This thesis investigates the performance and loads on a double-anhedral tip modern composite rotor. Double anhedral tips are a recent introduction in rotors with no research data available for understanding their behavior or modeling them adequately. The objectives were to bridge these gaps. Both experimental and analytical methods were employed to fulfill the objectives systematically. Double anhedral blades of 5.6-ft diameter were designed and fabricated. The blades had a uniform VR-7 airfoil profile, a D-spar, −16◦ twist, a 5◦ dihedral from 80%R to 95%R and a 15◦ anhedral from 95%R to the tip. The blades were built in-house using IM7/8552 graphite/epoxy prepreg weave. They were instrumented for strains and structural loads measurement. A two-bladed hingeless hub was designed and fabricated for the vacuum chamber to measure rotating frequencies (fan plot). The hover tests were performed on the Alfred Gessow Rotorcraft Center Mach-scaled four-bladed hingeless rig. Tests were carried out up to tip Mach number of 0.6 over a collective range of 0◦ to 10◦ . The rotor performance, blade structural loads, pitch link loads, and surface strains were measured. A double anhedral tip is a 3-D structure. Accordingly, a 3-D model was developed with CATIA (CAD), Cubit (hexahedral meshing), and X3D (aeromechanics). The 3-D CAD was constructed with guidance from Boeing to ensure the geometry was representative of a modern rotor yet generic enough to be open source for U.S. Gov-industry-academia joint study. The meshing used 27-node solid hexahedral elements, as needed by X3D. The pitch bearing was modeled with a joint commanded by control input. In total there were 3427 elements and approximately 100,000 degrees of freedom. Properties of the composite plies were acquired through in-house four-point bending coupon tests. The aerodynamic model used in-house CFD extracted C-81 decks and a lifting line with a refined free wake. The data acquired from tests were used to validate the model. A 3-D model of a straight blade was also developed as a baseline for comparison. These models have the same external and internal structure except for the tip. By comparing the behavior of the analytical models, insights were gained on the impacts of a double anhedral tip on the structural dynamics and aeromechanics in hover and forward flight. The local center of gravity offset at the tip appeared to make the blade softer. No performance gain was predicted in hover, however, the static flap, lag, and torsion moments at the root all decreased due to the vertical center of gravity offset in the tip portion. Strong 3-D strain patterns and multiple strain concentrations at the tip were predicted. In forward flight, the 4/rev vibratory vertical hub load and hub moments were predicted to increase by 15% and 100% respectively at tip speed ratio 0.1. Higher 1/rev oscillatory flap bending moment and 2/rev oscillatory lag bending moments were also predicted. The key conclusion is that the vertical center of gravity of the double anhedral tip can have significant ramifications on blade loads - reducing the static loads while increasing oscillatory harmonics particularly vibratory harmonics in forward flight. Systematic wind-tunnel tests are needed in future to dissect these effects. This thesis laid the foundations of that future through blade fabrication, vacuum and hover testing.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2023
538 $a Mode of access: World Wide Web
650 4 $a Aerospace engineering. $3 1002622
653 $a 3-D modeling
653 $a Aeromechanic analysis
653 $a Composite rotor
653 $a Double anhedral tip
653 $a Rotor experiments
655 7 $a Electronic books. $2 lcsh $3 542853
690 $a 0538
710 2 $a ProQuest Information and Learning Co. $3 783688
710 2 $a University of Maryland, College Park. $b Aerospace Engineering. $3 1018393
773 0 $t Dissertations Abstracts International $g 84-03B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29214553 $z click for full text (PQDT)