Mathematical modelling of dynamics plastic forming of aft fairing in missile transformed during flight

This article considers an innovative idea of decreasing the aerodynamic drag of missile by an inflight forming of an aft fairing of preferable geometry on the basis of plastic deformation of corrugated thin-walled shell by gasdynamic influence. The mathematical description of the interfaced impulse gas-dynamic and deformation processes of forming aft fairing in flight is given with the thermal effects. The algorithm for the numerical simulation of these co-occurring processes is presented. In the numerical experiment the authors proved preferred technical solutions that realize the principle of the flight transformation. The adequacy of the results obtained by the developed research instruments confirmed by comparing the numerical simulation data with the data of natural experiments. The numerical experiment preferred variants of the technical solutions implementing the principle of flight transformation are justified. In particular, it is shown that a membrane with a coaxial arrangement of the corrugations is more preferable than the radial arrangement. In this case we have managed to present the version of the mounting membrane with the best streamlined form during deployment of the membrane. The paper proposed two ways to improve the fairing: by changing the geometric parameters of the original thin-walled diaphragm; and due to variation of the deforming impacts. The best form is obtained when creating a combined force, which first of all transforms the central part and then the peripheral region of the corrugated shell. Also, the work shows a perspective direction based on the formation of the shell by a special gas jet. In general, on the basis of the research it became possible to prove the principal possibility of obtaining the specified geometrical form on board the missile by pulsed deformation of corrugated shell of the aft fairing, which is optimal from the viewpoint of reducing aerodynamic drag.