Abstract
The present paper provides an investigation of the effects of linear slosh dynamics on aeroelastic stability and response of flying wing configuration. The proposal of this work is to use reduced order model based on the theory of the equivalent mechanical models for the description of the sloshing dynamics. This model is then introduced into an integrated modeling that accounts for both rigid and elastic behavior of flexible aircraft. The formulation also provides for fully unsteady aerodynamics modeled in the frequency domain via doublet lattice method and recast in time-domain state-space form by means of a rational function approximation. The case study consists of the so-called body freedom flutter research model equipped with a single tank, partially filled with water, located underneath the center of mass of the aircraft. The results spotlight that neglecting such sloshing effects considering the liquid as a frozen mass may overshadow possible instabilities, especially for mainly rigid-body dynamics.
Highlights
Large passenger aircrafts are likely to have wings that are highly flexible structures, carrying an amount of fuel comparable in weight to that of their structural components, which can deform significantly when atmospheric turbulence or gust is encountered
The effects of sloshing on aircraft aeroelastic flutter stability was considered in Refs. [5, 6] where liquid dynamics were modeled by means of equivalent mechanical model (EMM) in Ref. [5] and frozen fluid approach in Ref. [6]
A detailed formulation of fluid–structure interaction is present in Ref. [7] that aim at integrating flight dynamics, aeroelasticity and sloshing dynamics of flexible launch vehicles
Summary
Large passenger aircrafts are likely to have wings that are highly flexible structures, carrying an amount of fuel comparable in weight to that of their structural components, which can deform significantly when atmospheric turbulence or gust is encountered. The effects of sloshing on aircraft aeroelastic flutter stability was considered in Refs. The equations of motion were linearized around aeroelastic trim conditions and recast in time-domain state-space form by approximating doublet lattice method fully unsteady aerodynamics via rational polynomial functions, obtaining a model that includes rigid-body, elastic, and aerodynamic state variables, as well as the variables related to the aforementioned fluid slosh dynamics. Employing as reference aircraft the body freedom flutter (BFF) with a parallelepiped tank (partially filled with water) placed underneath its center of mass, the effects of the sloshing dynamics on the stability and response have been investigated comparing the case in which the liquid is assumed as a frozen mass and the case in which the liquid is allowed to slosh. The paper is organized as follows: the equivalent mechanical model along with its integration into the integrated framework of flight dynamics and aeroelasticity is introduced in Sect. 2; the aeroelastic stability and response of the present test case, namely the considered flying wing research model, are illustrated in Sect. 3 along with the implementation of the control law; a section of concluding remarks ends the paper
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