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Propeller Whirl Flutter Study of a Distributed Electric Aircraft Using Multibody Dynamics Analysis.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Propeller Whirl Flutter Study of a Distributed Electric Aircraft Using Multibody Dynamics Analysis./
作者:	Nelson, Kyle Jeffrey.
面頁冊數:	1 online resource (139 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=29257173click for full text (PQDT)
ISBN:	9798351446059

Propeller Whirl Flutter Study of a Distributed Electric Aircraft Using Multibody Dynamics Analysis.
Nelson, Kyle Jeffrey.

Propeller Whirl Flutter Study of a Distributed Electric Aircraft Using Multibody Dynamics Analysis. - 1 online resource (139 pages)

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

Thesis (Ph.D.)--The University of Alabama, 2022.

Includes bibliographical references

The NASA X-57 experimental aircraft, is an adaptation of the twin turbo-prop Italian Tecnam P2006T. Designed to be lighter, quieter, and more efficient option than the traditional internal combustion option, the X-57 utilizes an electric propulsion system. Coupled with an electric propulsion system, a new lighter, thinner wing has been developed by NASA to increase the cruise efficiency of the aircraft. An electric propulsion system removes the need for fossil fuels, creates a zero emission aircraft, and helps achieve to a net 500% increase in cruise efficiency. Fourteen total propellers will be fitted to the X-57. Two main propellers located at the wingtip will be used throughout all phases of flight. The other 12 propellers are lift-augmentation devices only used in the take-off and landing phases of flight. The propeller downwash increases the flow speed of the wing and assists in avoiding stall at low speed. A unique feature of the high-lift propellers is that they can fold against their nacelles to reduce drag during cruise, then, deploy with centrifugal force when needed. These changes to the wing and propulsion system for the X-57 has increased concern for its aeroelastic stability, in particular, propeller whirl flutter.Propeller whirl flutter is an aeroelastic instability where the coupled motion of the airframe and propeller becomes unstable. This study uses multibody dynamics analysis to predict the propeller whirl flutter stability of the X-57 Maxwell. Multibody dynamics software has become increasingly popular in the rotorcraft communities because of their generality and capability to model complex, coupled systems. Dymore is a finite element (FE) based multibody dynamics code for the comprehensive modeling of nonlinear flexible multibody systems. The elements library in Dymore includes rigid and deformable bodies as well as joint elements. The aerodynamics are modeled using a built-in lifting line model but can also be coupled with an external code. The differential-algebraic equations of motion are established using a Lagrange multiplier method that is solved in a time marching scheme. The X-57 model being used in Dymore has: 1. a beam model of the propeller blades, and 2. a modal super element representation of the aircraft. The beam models in Dymore are derived from NASTRAN FEM model for the wing and propeller blades. Tuned springs are used at the wingtip to capture the pylon modes of the tip propeller. A torsional spring is used to constrain the folding motion of the high-lift propellers. The modal super element model that is used is a reduced order model of the full NASTRAN model of the X-57 Maxwell. This model retains 6 rigid-body modes, the first 100 elastic modes, and the degrees of freedom associated with the interface nodes chosen to be included in the model.CAMRAD II is another multibody dynamics code that was developed by Wayne Johnson, and it will be a source of comparison for Dymore. Both codes have been established as being able to accurately predict the whirl flutter boundary of tilt-rotor aircraft [1,2]. The scope of this study is to subject the X-57 propellers and a modal representation of the full-span wing with fuselage to a variety of conditions to determine the whirl flutter boundary of the aircraft. Isolated propellers are developed and compared against wind tunnel data to validate the aerodynamic models used. A study to subject an isolated propeller with increasing viscous damping about the folding hinge is performed to validate the stability of the folding blade motion and compared against experimental data. A baseline modal super-element model is used to compared against previous Dymore and CAMRAD results for a full-span model. This study only considers the influence of the tip-propeller to whirl flutter stability. The high-lift propellers are modeled as rigid bodies in the previous Dymore and CAMRAD models. A sensitivity study is carried out to compare the location of the high-lift propellers on the stability of the X-57. This study showed that the out-board propellers have the highest damping contribution to propeller whirl flutter of the aircraft. A parametric study is performed to determine the whirl flutter stability of the full system with contribution from all 14 propellers by varying tip and high-lift propeller RPM and flight speed. The results show that the scheduled high-lift propeller RPM drive the out-of-plane symmetric bending mode unstable at low speed.

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

Mode of access: World Wide Web

ISBN: 9798351446059Subjects--Topical Terms:

1002622
Aerospace engineering.
Subjects--Index Terms:

AeroelasticityIndex Terms--Genre/Form:

542853
Electronic books.

Propeller Whirl Flutter Study of a Distributed Electric Aircraft Using Multibody Dynamics Analysis.
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504 $a Includes bibliographical references
520 $a The NASA X-57 experimental aircraft, is an adaptation of the twin turbo-prop Italian Tecnam P2006T. Designed to be lighter, quieter, and more efficient option than the traditional internal combustion option, the X-57 utilizes an electric propulsion system. Coupled with an electric propulsion system, a new lighter, thinner wing has been developed by NASA to increase the cruise efficiency of the aircraft. An electric propulsion system removes the need for fossil fuels, creates a zero emission aircraft, and helps achieve to a net 500% increase in cruise efficiency. Fourteen total propellers will be fitted to the X-57. Two main propellers located at the wingtip will be used throughout all phases of flight. The other 12 propellers are lift-augmentation devices only used in the take-off and landing phases of flight. The propeller downwash increases the flow speed of the wing and assists in avoiding stall at low speed. A unique feature of the high-lift propellers is that they can fold against their nacelles to reduce drag during cruise, then, deploy with centrifugal force when needed. These changes to the wing and propulsion system for the X-57 has increased concern for its aeroelastic stability, in particular, propeller whirl flutter.Propeller whirl flutter is an aeroelastic instability where the coupled motion of the airframe and propeller becomes unstable. This study uses multibody dynamics analysis to predict the propeller whirl flutter stability of the X-57 Maxwell. Multibody dynamics software has become increasingly popular in the rotorcraft communities because of their generality and capability to model complex, coupled systems. Dymore is a finite element (FE) based multibody dynamics code for the comprehensive modeling of nonlinear flexible multibody systems. The elements library in Dymore includes rigid and deformable bodies as well as joint elements. The aerodynamics are modeled using a built-in lifting line model but can also be coupled with an external code. The differential-algebraic equations of motion are established using a Lagrange multiplier method that is solved in a time marching scheme. The X-57 model being used in Dymore has: 1. a beam model of the propeller blades, and 2. a modal super element representation of the aircraft. The beam models in Dymore are derived from NASTRAN FEM model for the wing and propeller blades. Tuned springs are used at the wingtip to capture the pylon modes of the tip propeller. A torsional spring is used to constrain the folding motion of the high-lift propellers. The modal super element model that is used is a reduced order model of the full NASTRAN model of the X-57 Maxwell. This model retains 6 rigid-body modes, the first 100 elastic modes, and the degrees of freedom associated with the interface nodes chosen to be included in the model.CAMRAD II is another multibody dynamics code that was developed by Wayne Johnson, and it will be a source of comparison for Dymore. Both codes have been established as being able to accurately predict the whirl flutter boundary of tilt-rotor aircraft [1,2]. The scope of this study is to subject the X-57 propellers and a modal representation of the full-span wing with fuselage to a variety of conditions to determine the whirl flutter boundary of the aircraft. Isolated propellers are developed and compared against wind tunnel data to validate the aerodynamic models used. A study to subject an isolated propeller with increasing viscous damping about the folding hinge is performed to validate the stability of the folding blade motion and compared against experimental data. A baseline modal super-element model is used to compared against previous Dymore and CAMRAD results for a full-span model. This study only considers the influence of the tip-propeller to whirl flutter stability. The high-lift propellers are modeled as rigid bodies in the previous Dymore and CAMRAD models. A sensitivity study is carried out to compare the location of the high-lift propellers on the stability of the X-57. This study showed that the out-board propellers have the highest damping contribution to propeller whirl flutter of the aircraft. A parametric study is performed to determine the whirl flutter stability of the full system with contribution from all 14 propellers by varying tip and high-lift propeller RPM and flight speed. The results show that the scheduled high-lift propeller RPM drive the out-of-plane symmetric bending mode unstable at low speed.
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538 $a Mode of access: World Wide Web
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650 4 $a Fluid mechanics. $3 528155
650 4 $a Electrical engineering. $3 649834
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653 $a X-57 Maxwell
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773 0 $t Dissertations Abstracts International $g 84-03B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29257173 $z click for full text (PQDT)