Absolute Nodal Coordinate Formulations for Aeroelastic Analysis of Next-Generation Aircraft Wings

2021 ◽  
Author(s):  
Keisuke Otsuka ◽  
Shuonan Dong ◽  
Kanjuro Makihara

Abstract Future aircraft have a high aspect ratio wing (HARW). The low induced drag of the wing can reduce fuel consumption, which enables eco-friendly flight. HARW cannot be designed by using conventional linear aeroelastic analysis methods because it undergoes very flexible motion. Although absolute nodal coordinate formulations (ANCF) have been widely used for analyzing various flexible structures, their application to HAWR is limited because the derivation of the ANCF elastic force for wing cross section is difficult. In this paper, we first describe three ANCF-based beam models that address the difficulty. The three models have different characteristics. Second, an aeroelastic coupling between the beam models and a medium-fidelity aerodynamic model based on unsteady vortex lattice method (UVLM) is briefly explained. Especially, the advantage of ANCF in the aeroelastic coupling is emphasized. Finally, we newly compare the three ANCF-based models in structural and aeroelastic analyses. From the viewpoint of the convergence performance and calculation time, we found the best ANCF-based beam model among the three models in static structural and aeroelastic analyses, while the three models have comparable performances in dynamic structural and aeroelastic analyses. These findings contribute to the development of aeroelastic analysis framework based on ANCF and the design of next-generation aircraft wings.

2021 ◽  
Vol 55 (5) ◽  
pp. 179-195
Author(s):  
Luu Quang Hung ◽  
Zhuang Kang ◽  
Li Shaojie

Abstract In this paper, the dynamics of the flexible riser are investigated based on the absolute nodal coordinate formulation (ANCF). The stiffness, generalized elastic force, external load, and mass matrixes of the element are deduced based on the principle of energy conversion and assembled with the finite element method. The motion equation of the flexible riser is established. The influence of the environmental load conditions on the flexible riser model is studied in the MATLAB environment. Moreover, the accuracy and reliability of the programs are verified for a beam model with theoretical solutions. Finally, the static and dynamic characteristics of the flexible riser are analyzed, systematically adopting the ANCF method, which in turn proves the effectiveness and feasibility of the ANCF. Therefore, the proposed method is a powerful scheme for investigating the dynamics of flexible structures with large deformation in ocean engineering.


2020 ◽  
Vol 16 (1) ◽  
Author(s):  
Keisuke Otsuka ◽  
Yinan Wang ◽  
Kanjuro Makihara

Abstract High aspect ratio wings are potential candidates for use in atmospheric satellites and civil aircraft as they exhibit a low induced drag, which can reduce the fuel consumption. Owing to their slender and light weight configuration, such wings undergo highly flexible aeroelastic static and dynamic deformations that cannot be analyzed using conventional linear analysis methods. An aeroelastic analysis framework based on the absolute nodal coordinate formulation (ANCF) can be used to analyze the static and dynamic deformations of high aspect ratio wings. However, owing to the highly nonlinear elastic force, the statically deformed wing shape during steady flight cannot be efficiently obtained via static analyses. Therefore, an ANCF with a vector-strain transformation (ANCF-VST) was proposed in this work. Considering the slender geometry of high aspect ratio wings, the nodal vectors of an ANCF beam element were transformed to the strains. In this manner, a constant stiffness matrix and reduced degrees-of-freedom could be generated while capturing the highly flexible deformations accurately. The ANCF-VST exhibited superior convergence performance and accuracy compared to those of analytical approaches and other nonlinear beam formulations. Moreover, an aeroelastic analysis flow coupling the ANCF-VST and an aerodynamic model based on the unsteady vortex lattice method was proposed to perform the static and dynamic analyses successively. The proposed and existing aeroelastic frameworks exhibited a good agreement in the analyses, which demonstrated the feasibility of employing the proposed framework to analyze high aspect ratio wings.


2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Sen Mao ◽  
Changchuan Xie ◽  
Lan Yang ◽  
Chao Yang

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.


Author(s):  
Lan Yang ◽  
Changchuan Xie ◽  
Chao Yang

Geometrically exact vortex lattice method and panel method are presented in this paper to deal with aerodynamic load computation for geometrically nonlinear static aeroelastic problems. They are combined with geometrically nonlinear finite element method through surface spline interpolation in the loosely-coupled iteration. From the perspective of theoretical research, both vortex lattice method and panel method are based on the full potential equation and able to model the deflection and twist of the wing, while vortex lattice method is based on the thin airfoil theory, and panel method is suitable for thick wings. Although the potential flow equation is linear, the introduction of geometrically exact boundary conditions makes it significantly different from the linear aeroelastic analysis. The numerical results of a high aspect ratio wing are provided to declare the influence of large deformation on nonlinear static aeroelastic computation compared with linear analysis. Aeroelastic analyses based on geometrically exact vortex lattice method and panel method are also compared with the results of computational fluid dynamics/computational structural dynamics coupling method and the wind tunnel test data. The nonlinear static aeroelastic analysis agrees with the measurement even in considerably large deformation situations.


Author(s):  
Alexandre Capitao Patrao ◽  
Richard Avellán ◽  
Anders Lundbladh ◽  
Tomas Grönstedt

Inspired by Prandtl’s theory on aircraft wings with minimum induced drag, the authors introduced a double-bladed propeller, the Boxprop, intended for high-speed flight. The basic idea is to join the propeller blades pair-wise at the tip to improve aerodynamics and mechanical properties compared to the conventional propeller. The rather complex geometry of the double blades gives rise to new questions, particularly regarding the aerodynamics. This paper presents a propeller wake energy analysis method which gives a better understanding of the potential performance benefits of the Boxprop and a means to improve its design. CFD analysis of a five bladed Boxprop demonstrated its ability to generate typical levels of cruise thrust at a flight speed of Mach 0.75. The present work shows that the near tip velocity variations in the wake are weaker for this propeller than a conventional one, which is an indication that a counter rotating propeller designed with a Boxprop employed at the front may exhibit lower interaction noise.


Author(s):  
Alexander H. Pesch ◽  
Tamunomiesiya LongJohn ◽  
Kristopher Wagner ◽  
Brian J. McAndrews

As composite materials are becoming increasingly applied in actively controlled flexible structures, the need for practical uncertainty bounding to capture the effect of normal manufacturing variations on their dynamic behavior is also increasing. Currently, there is a lack of quantification of manufacturing variation of composite materials cast in a robust control framework. This work presents a simple experimental study on a particular case of composite member. The modal parameters of a set of 12 unidirectional carbon fiber reinforce polymer beams are identified. A nominal finite element model is numerically fit to the average experimental natural frequencies and antiresonances. The model is augmented with real parametric uncertainties placed on the modal parameters. The bound on the uncertainties is found both deterministically, to capture all experimentally observed data, and stochastically using a predetermined confidence interval. The two uncertainty bounding approaches are compared through the resulting bound on the beam model frequency response. Also, simulations are conducted to compare possible time responses using the two uncertainty bounds. It is found that the utilized structure of parametric uncertainties is effective at capturing the experimentally observed behavior.


AIAA Journal ◽  
2017 ◽  
Vol 55 (2) ◽  
pp. 668-672 ◽  
Author(s):  
Thomas Lambert ◽  
Grigorios Dimitriadis

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