Propeller Whirl Flutter Stability and Its Influence on X-57 Aircraft Design

Hoover, Christian B.; Shen, Jinwei; Kreshock, Andrew R.

doi:10.2514/1.c034950

Cited by 11 publications

(2 citation statements)

References 15 publications

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“…As other authors already stated (e.g. [11]), the lifting surface aerodynamics have great influence on the stability characteristics of the system and are stabilising in this case, as the out-of-plane bending provides large amounts of aerodynamic damping. Figure 17 shows this for the most critical dynamic system with low stiffness shock mounts.…”

Section: Full Model With Aerodynamicsmentioning

confidence: 55%

Parametric whirl flutter study using different modelling approaches

Koch

2021

CEAS Aeronaut J

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This 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.

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Section: Full Model With Aerodynamicsmentioning

confidence: 55%

Parametric whirl flutter study using different modelling approaches

Koch

2021

CEAS Aeronaut J

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“…The wing influences the aerodynamic performance of the propeller by inducing velocity at its disk [9], developing a slipstream [5], and increasing the efficiency of the propulsion [9,13]. In addition to the rigid wing, there are also a few papers available that address the flexible wing in the propeller/wing system [14][15][16]. This research focused on the aeroelasticity phenomenon affected by the propeller.…”

Section: Introductionmentioning

confidence: 99%

Influence of Aerodynamic Interaction on Performance of Contrarotating Propeller/Wing System

et al. 2022

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This paper gives a quantitative account of the influence of slipstream on the aerodynamic performance of a contrarotating propeller (CRP)/wing system, and compares it with the CRP and clean wing. To accurately evaluate the complex aerodynamic interaction, the unsteady Reynolds-averaged Navier–Stokes approach using the sliding mesh method is performed at a typical freestream velocity of 30 m/s. Four different critical parameters, including the freestream angle of attack (AoA), axial spacing between the front propeller (FP) and rear propeller (RP), number of blades, and rotational speed, are considered in the present work. The results show that the thrust coefficient, power coefficient, and propulsion efficiency of the CRP/wing system change sharply and the difference in amplitude between adjacent waves is large. In particular, the propeller slipstream has a significant impact on the lift–drag performance of the wing in the case of a nonzero AoA. The presence of a wing also increases the efficiency of propulsion due to the recovery of vortices. In the case of a small axial spacing, the thrust coefficient value of the FP is significantly smaller than that of the RP. However, when the axial spacing exceeds a certain value, the opposite relationship is obtained. When the rotational speed increases from 3695 RPM to 8867 RPM, the lift coefficient and drag coefficient of the wing gradually increase.

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