Propeller influence on the aeroelastic stability of High Altitude Long Endurance aircraft

2020 ◽  
Vol 124 (1275) ◽  
pp. 703-730 ◽  
Author(s):  
P.C. Teixeira ◽  
C.E.S. Cesnik
Keyword(s):  
High Altitude ◽  
Data Series ◽  
Aeroelastic Stability ◽  
Time Data ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Lifting Surfaces ◽  
Structural Case ◽  
The Stability ◽  
Long Endurance

AbstractThis work investigates the propeller’s influence on the stability of High Altitude Long Endurance aircraft, incorporating all resultant loads at the propeller hub, propeller slipstream, and gyroscopic loads. Such effects are usually neglected in the aeroelastic simulation of HALE aircraft. For that goal, a previously developed framework, which couples a geometrically nonlinear structural solver with an Unsteady Vortex Lattice method (uVLM) for lifting surfaces and a Viscous Vortex Particle (VVP) method for propeller slipstream, was employed to generate time-data series. Also, a method, based on a combination of Proper Orthogonal Decomposition and system identification, to extract dynamic information (frequencies, damping, and modes) of the aircraft from a time-series signal is proposed and successfully tested for a purely structural case, for which reference data is available. The method is then applied to investigate the stability of aeroelastic cases. The results demonstrate that the presence of propellers can influence the aeroelastic stability of a Very Flexible Aircraft.

scholarly journals Computational Study of a Transverse Rotor Aircraft in Hover Using the Unsteady Vortex Lattice Method

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Juan D. Colmenares ◽  
Omar D. López ◽  
Sergio Preidikman
Keyword(s):  
Vortex Lattice ◽  
Computational Study ◽  
Pitching Moment ◽  
Considerable Influence ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Geometric Configurations ◽  
Hover Flight ◽  
High Reynolds ◽  
The Stability

This paper presents the simulation of a two-rotor aircraft in different geometric configurations during hover flight. The analysis was performed using an implementation of the unsteady vortex-lattice method (UVLM). A description of the UVLM is presented as well as the techniques used to enhance the stability of results for rotors in hover flight. The model is validated for an isolated rotor in hover, comparing numerical results to experimental data (high-Reynolds, low-Mach conditions). Results show that an exclusion of the root vortex generates a more stable wake, without affecting results. Results for the two-rotor aircraft show an important influence of the number of blades on the vertical thrust. Furthermore, the geometric configuration has a considerable influence on the pitching moment.

scholarly journals Fast and accurate quasi-3D aerodynamic methods for aircraft conceptual design studies

2020 ◽  
pp. 1-25
Author(s):  
O. Şugar-Gabor ◽  
A. Koreanschi
Keyword(s):  
Computational Time ◽  
Shape Optimisation ◽  
Surface Geometry ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Recent Developments ◽  
Line Theory ◽  
Lifting Surfaces ◽  
3D Methods ◽  
Aircraft Conceptual Design

ABSTRACT In this paper, recent developments in quasi-3D aerodynamic methods are presented. At their core, these methods are based on the lifting-line theory and vortex lattice method, but with a relaxed set of hypotheses, while also considering the effect of viscosity (to a certain degree) by introducing a strong non-linear coupling with two-dimensional viscous aerofoil aerodynamics. These methods can provide more accurate results compared with their inviscid classical counterparts and have an extended range of applicability with respect to the lifting surface geometry. Verification results are presented for both steady-state and unsteady flows, as well as case studies related to their integration into aerodynamic shape optimisation tools. The good accuracy achieved using relatively low computational time makes such quasi-3D methods a solid choice for conducting conceptual-level design and optimisation of lifting surfaces.

Calculation of the Aerodynamic Forces on Automotive Lifting Surfaces

1985 ◽  
Vol 107 (4) ◽  
pp. 438-443 ◽  
Author(s):  
J. Katz
Keyword(s):  
Steady State ◽  
Vortex Lattice ◽  
Numerical Technique ◽  
Angle Of Attack ◽  
Ground Effect ◽  
Aerodynamic Forces ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Close Proximity ◽  
Lifting Surfaces

A numerical technique was developed to investigate the performance of automotive lifting surfaces in close proximity to ground. The model is based on the Vortex Lattice Method and includes freely-deforming wake elements. The ground effect was simulated by reflection and both steady and unsteady pressures and loads on various wing planforms were considered. Calculated results are presented for wings having both positive and negative incidences, with and without ground effect. Also the transient lift of a wing in a plunging motion was analyzed in ground proximity and at a negative angle of attack. Finally the periodic lift fluctuations on the front winglet of a racing car, due to its suspension oscillations, were calculated and found to exceed approximately twice the steady-state value.

scholarly journals Nonlinear Aeroelastic Simulations and Stability Analysis of the Pazy Wing Aeroelastic Benchmark

Aerospace ◽  
2021 ◽  
Vol 8 (10) ◽  
pp. 308
Author(s):  
Jonathan Hilger ◽  
Markus Raimund Ritter
Keyword(s):  
Stability Analysis ◽  
Wind Tunnel ◽  
Vortex Lattice ◽  
Structural Model ◽  
State Space Model ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Aeroelastic Simulations ◽  
The Stability ◽  
German Aerospace

The Pazy wing aeroelastic benchmark is a highly flexible wind tunnel model investigated in the Large Deflection Working Group as part of the Third Aeroelastic Prediction Workshop. Due to the design of the model, very large elastic deformations in the order of 50% span are generated at highest dynamic pressures and angles of attack in the wind tunnel. This paper presents static coupling simulations and stability analyses for selected onflow velocities and angles of attack. Therefore, an aeroelastic solver developed at the German Aerospace Center (DLR) is used for static coupling simulations, which couples a vortex lattice method with the commercial finite element solver MSC Nastran. For the stability analysis, a linearised aerodynamic model is derived analytically from the unsteady vortex lattice method and integrated with a modal structural model into a monolithic aeroelastic discrete-time state-space model. The aeroelastic stability is then determined by calculating the eigenvalues of the system’s dynamics matrix. It is shown that the stability of the wing in terms of flutter changes significantly with increasing deflection and is heavily influenced by the change in modal properties, i.e., structural eigenvalues and eigenvectors.

Generalized vortex lattice method for planar supersonic flow

AIAA Journal ◽  
1997 ◽  
Vol 35 ◽  
pp. 1230-1233
Author(s):  
Paulo A. O. Soviero ◽  
Hugo B. Resende
Keyword(s):  
Supersonic Flow ◽  
Vortex Lattice ◽  
Lattice Method ◽  
Vortex Lattice Method

scholarly journals Static Aeroelastic Characteristics of Morphing Trailing-Edge Wing Using Geometrically Exact Vortex Lattice Method

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Sen Mao ◽  
Changchuan Xie ◽  
Lan Yang ◽  
Chao Yang
Keyword(s):  
Vortex Lattice ◽  
Deflection Angle ◽  
Aircraft Design ◽  
Analysis Method ◽  
Lattice Method ◽  
Trailing Edge ◽  
Vortex Lattice Method ◽  
Analysis And Design ◽  
Aeroelastic Analysis ◽  
Typical Model

A morphing trailing-edge (TE) wing is an important morphing mode in aircraft design. In order to explore the static aeroelastic characteristics of a morphing TE wing, an efficient and feasible method for static aeroelastic analysis has been developed in this paper. A geometrically exact vortex lattice method (VLM) is applied to calculate the aerodynamic forces. Firstly, a typical model of a morphing TE wing is chosen and built which has an active morphing trailing edge driven by a piezoelectric patch. Then, the paper carries out the static aeroelastic analysis of the morphing TE wing and corresponding simulations were carried out. Finally, the analysis results are compared with those of a traditional wing with a rigid trailing edge using the traditional linearized VLM. The results indicate that the geometrically exact VLM can better describe the aerodynamic nonlinearity of a morphing TE wing in consideration of geometrical deformation in aeroelastic analysis. Moreover, out of consideration of the angle of attack, the deflection angle of the trailing edge, among others, the wing system does not show divergence but bifurcation. Consequently, the aeroelastic analysis method proposed in this paper is more applicable to the analysis and design of a morphing TE wing.

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