Quasi-static deformations effect on aeroelasticity characteristics of an aircraft with high aspect ratio wing

Аuthors

Bezuevskii A. V.^*, Ishmuratov F. Z.^**

Central Aerohydrodynamic Institute named after N.E. Zhukovsky (TsAGI), 1, Zhukovsky str., Zhukovsky, Moscow Region, 140180, Russia

*e-mail: stataer@tsagi.ru
**e-mail: fanil.ishmuratov@tsagi.ru

Abstract

One of the ways to increase the aerodynamic quality of modern and prospective aircraft consists in wing aspect ratio increasing. Such increasing leads to the occurrence of various new aspects of the structure loading, strength and aeroelasticity. One of these aspects is increasing of the wing flexibility, and as a consequence, possible in-flight structures deformations effect on aeroelasticity characteristics.

The paper presents a review of publications on the deformation effect on various aeroelasticity characteristics. It suggests and substantiates a computational method for studying the effect of quasi-static deformations of the wing on static and dynamic aeroelasticity of an aircraft. This method is based on automated generation of a set of aircraft computational models using the Ritz polynomial method. The paper presents the examples of a wing in-flight deformations effect on characteristics of static elasticity, frequency and shape of elastic vibrations, and flutter characteristics.

The results of the developed method application for aircraft of various configuration allowed establishing the main regularities of the effect of structure's deformation on aeroelasticity characteristics.

The effect of in-flight deformations on the characteristics of static aeroelasticity and load is determined by: 1) effective wing span decrease; 2) aerodynamic forces direction changing; 3) increase of the effective dihedral angle. Characteristics of longitudinal motion can reduce by 5-6%, while characteristics of lateral motion can increase or decrease by 5-15%.

The dynamic aeroelasticity characteristics change is determined mainly by the increase in the interaction of torsional oscillations of a wing with bending vibrations in the chord plane. For the unmanned aerial vehicles with a wing of extremely high aspect ratio, this effect can lead to a significant decrease in flutter speed (up to 30-50%). For modern airliners, the decrease in flutter speed due to the in-flight deformation does not exceed a few percent and lies within the accuracy of numerical methods.

An important feature of the method is its integration into a multidisciplinary design complex ARGON, validated while solving aeroelasticity problems in many practical applications.

Keywords:

modal analysis, high-aspect wing, aeroelasticity characteristics, flutter limit

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