scholarly journals Aeroelastic Stability of Turboprop Aircraft: Whirl Flutter

2018 ◽  
Author(s):  
Jiří Čečrdle
Keyword(s):  
Aeroelastic Stability ◽  
Whirl Flutter

scholarly journals Parametric whirl flutter study using different modelling approaches

2021 ◽  
Author(s):  
Christopher Koch
Keyword(s):  
Unsteady Aerodynamics ◽  
Beam Model ◽  
Electric Motors ◽  
Aeroelastic Stability ◽  
Aerodynamic Model ◽  
Lifting Surface ◽  
Aeroelastic Model ◽  
Strip Theory ◽  
Engine Mount ◽  
Whirl Flutter

AbstractThis paper demonstrates the importance of assessing the whirl flutter stability of propeller configurations with a detailed aeroelastic model instead of local pylon models. Especially with the growing use of electric motors for propulsion in air taxis and commuter aircraft whirl flutter becomes an important mode of instability. These configurations often include propeller which are powered by lightweight electric motors and located at remote locations, e.g. the wing tip. This gives rise to an aeroelastic instability called whirl flutter, involving the gyroscopic whirl modes of the engine. The driving parameters for this instability are the dynamics of the mounting structure. Using a generic whirl flutter model of a propeller at the tip of a lifting surface, parameter studies on the flutter stability are carried out. The aeroelastic model consists of a dynamic MSC.Nastran beam model coupled with the unsteady ZAERO ZONA6 aerodynamic model and strip theory for the propeller aerodynamics. The parameter studies focus on the influence of different substructures (ranging from local engine mount stiffness to global aircraft dynamics) on the aeroelastic stability of the propeller. The results show a strong influence of the level of detail of the aeroelastic model on the flutter behaviour. The coupling with the lifting surface is of major importance, as it can stabilise the whirl flutter mode. Including wing unsteady aerodynamics into the analysis can also change the whirl flutter behaviour. This stresses the importance of including whirl flutter in the aeroelastic stability analysis on aircraft level.

scholarly journals High-Fidelity Fin–Actuator System Modeling and Aeroelastic Analysis Considering Friction Effect

2021 ◽  
Vol 11 (7) ◽  
pp. 3057
Author(s):  
Jin Lu ◽  
Zhigang Wu ◽  
Chao Yang
Keyword(s):  
System Modeling ◽  
Past Research ◽  
High Fidelity ◽  
Aeroelastic Stability ◽  
Aeroelastic Analysis ◽  
Structural Nonlinearities ◽  
Flutter Boundary ◽  
Actuator System ◽  
Friction Models ◽  
Comparison Of The Results

Both the dynamic characteristics and structural nonlinearities of an actuator will affect the flutter boundary of a fin–actuator system. The actuator models used in past research are not universal, the accuracy is difficult to guarantee, and the consideration of nonlinearity is not adequate. Based on modularization, a high-fidelity modeling method for an actuator is proposed in this paper. This model considers both freeplay and friction, which is easy to expand. It can be directly used to analyze actuator characteristics and perform aeroelastic analysis of fin–actuator systems. Friction can improve the aeroelastic stability, but the mechanism of its influence on the aeroelastic characteristics of the system has not been reported. In this paper, the LuGre model, which can better reflect the friction characteristics, was integrated into the actuator. The influence of the initial condition, freeplay, and friction on the aeroelastic characteristics of the system was analyzed. The comparison of the results with the previous research shows that oversimplified friction models are not accurate enough to reflect the mechanism of friction’s influence. By changing the loads, material, and geometry of contact surfaces, flutter can be effectively suppressed, and the power loss caused by friction can be minimized.

scholarly journals Aeroelastic Stability Analysis of Electric Aircraft Wings with Distributed Electric Propulsors

Aerospace ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 100
Author(s):  
Mohammadreza Amoozgar ◽  
Michael I. Friswell ◽  
Seyed Ahmad Fazelzadeh ◽  
Hamed Haddad Khodaparast ◽  
Abbas Mazidi ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Electric Propulsion ◽  
Aeroelastic Stability ◽  
Concentrated Mass ◽  
High Lift ◽  
Aircraft Wings ◽  
Time Space ◽  
Beam Equations ◽  
Geometrically Exact Beam ◽  
Electric Aircraft

In this paper, the effect of distributed electric propulsion on the aeroelastic stability of an electric aircraft wing was investigated. All the electric propulsors, which are of different properties, are attached to the wing of the aircraft in different positions. The wing structural dynamics was modelled by using geometrically exact beam equations, while the aerodynamic loads were simulated by using an unsteady aerodynamic theory. The electric propulsors were modelled by using a concentrated mass attached to the wing, and the motor’s thrust and angular momentum were taken into account. The thrust of each propulsor was modelled as a follower force acting exactly at the centre of gravity of the propulsor. The nonlinear aeroelastic governing equations were discretised using a time–space scheme, and the obtained results were verified against available results and very good agreement was observed. Two case studies were considered throughout the paper, resembling two flight conditions of the electric aircraft. The numerical results show that the tip propulsor thrust, mass, and angular momentum had the most impact on the aeroelastic stability of the wing. In addition, it was observed that the high-lift motors had a minimal effect on the aeroelastic stability of the wing.

Aeroelastic stability analysis using stochastic structural modifications

2020 ◽  
Vol 477 ◽  
pp. 115333 ◽  
Author(s):  
L.J. Adamson ◽  
S. Fichera ◽  
J.E. Mottershead
Keyword(s):  
Stability Analysis ◽  
Aeroelastic Stability ◽  
Structural Modifications
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