Effects of Sloshing on Flutter Prediction of Partially Liquid-Filled Circular Cylindrical Shell

Dynamic stability of a liquid-filled circular cylindrical shell subjected to supersonic flow and influenced by a moving inside fluid-free surface is investigated simultaneously. Structural modeling is based on the combination of Sanders thin shell theory and the standard finite element method. The shape functions are found from an exact solution of shell theory that yields fast and precise convergence. A first-order piston theory was applied to derive aerodynamic damping and stiffness matrices coupled with the shell elastic deformation. The fluid inside the shell is modeled as a potential variable at each node of the structure elements, and its motion is expressed in terms of nodal degrees of freedom at the interface of the fluid and shell. The effect of axial loading is also investigated by developing a geometrical stiffness matrix. Results showed that ignoring the fluid sloshing effect leads to overprediction of critical flutter velocities, and the most significant deviations are found for short and wide shells with high values of liquid-filling ratios. This hybrid numerical-analytical software package can he used effectively for aeroelastic analysis and the design of shells of revolution at less computational cost compared with commercial finite element packages.