Flutter of a Circular Cylindrical Shell Subjected to Supersonic External Flow by Considering Internal Fluid Effects through a Novel Formulation

In the current paper, the flutter of a circular cylindrical shell containing an internal fluid while subjected to supersonic external flow has been investigated. It is noted that the internal fluid is formulated through a simple and novel model, in which the fluid is only represented by the free surface as well as the surrounding structural degrees of freedoms. To this end, a computational Fluid-structure interaction (FSI) model within the framework of the finite element method is developed. The internal liquid is represented by a more sophisticated model, referred to as and the shell structure is modeled by Sanders’ shell theory. The aerodynamic pressure loading is approximated by the first-order piston theory. The initial geometric stiffness due to pre-stresses in the initial configuration stemming from the fluid hydrostatic pressure, internal pressure, and axial compression load is also considered. The validity of the derived formulation is established, using some verification examples. The obtained results reveal as the filling ratio is increased from 0 to 1, the flutter speed increases first as the filling ratio is increased and reaches the maximum value the 0.5 filling ratio; then, it decreases when the filling ratio is further increased and reaches the critical value of an empty shell the 1.0 filling ratio.