The interference aerodynamics caused by the wing elasticity during store separation

Abstract

Air-launch-to-orbit is the technology that has stores carried aloft and launched the store from the plane to the orbit. The separation between the aircraft and store is one of the most important and difficult phases in Air-launch-to-orbit technology. There exists strong aerodynamic interference between the aircraft and the store in store separation. When the aspect ratio of the aircraft is large, the elastic deformations of the wing must be considered. The main purpose of this article is to study the influence of the interference aerodynamics caused by the elastic deformations of the wing to the unsteady aerodynamics of the store. By solving the coupled functions of unsteady Navier-Stokes equations, six degrees of freedom dynamic equations and structural dynamic equations simultaneously, the store separation with the elastic deformation of the aircraft considered is simulated numerically. And the interactive aerodynamic forces are analyzed. The study shows that the interference aerodynamics is obvious at earlier time during the separation, and the dominant frequency of the elastic wing determines the aerodynamic forces frequencies of the store. Because of the effect of the interference aerodynamics, the roll angle response and pitch angle response increase. When the store is mounted under the wingtip, the additional aerodynamics caused by the wingtip vortex is obvious, which accelerate the divergence of the lateral force and the lateral-directional attitude angle of the store. This study supports some beneficial conclusions to the engineering application of the air-launch-to-orbit.

Mechanism of characteristic change of panel flutter caused by oblique shock impingement

“…8,30 The in-house CFD solver GFSI is used to solve the Euler equations, which has been fully tested for fluid-structure simulations in our previous works. 42,43,46,47 The integral form of the Euler equations can be written as:where W=[ρ,ρu,ρv,ρw,e]T is the vector of conservative variables, p is the density, u, v, and w are the velocity components in x, y, and z directions, and e is the internal energy per unit mass. F(W,Vgrid) is the inviscid flux vector.…”

“…The same method has been successfully applied in our previous research. 42,46,47 The interpolation function is expressed as:where Θ(B) represents the boundary point set, w(Δxi) is the displacements of the node i, and Δxib=xib−xi. The speed of projection is determined by the exponent a, which should be in the range of 3–5.…”

“…8,30 The inhouse CFD solver GFSI is used to solve the Euler equations, which has been fully tested for fluid-structure simulations in our previous works. 42,43,46,47 The integral form of the Euler equations can be written as:…”

“…The same method has been successfully applied in our previous research. 42,46,47 The interpolation function is expressed as:…”

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“…Wang et al [13] used the loose coupling method to analyze the influence of elastic and rigid wings on the separation trajectory of external stores and found quite different trajectories for these two cases. Yang et al [14] simulated the release of external stores for elastic wings based on the modal superposition method. They revealed that the elastic deformation of wings at the initial stage of separation greatly affects the trajectory of external stores.…”