ON COMPARING THEORY AND EXPERIMENT FOR THE SUPERSONIC FLUTTER OF CIRCULAR CYLINDRICAL SHELLS.
GRADUATE AERONAUTICAL LABS CALIF INST OF TECH PASADENA
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The flutter boundaries obtained from recent experiments on the supersonic flutter of circular cylindrical shells are compared with various theoretical predictions. Following Voss, a model analysis is used in conjunction with different aerodynamic approximations - namely, piston theory and the potential solution of Leonard and Hedgepeth. It was found that the pressurized cylindrical shells fluttered at a lower level of free stream energy than predicted by the theory. Of the two results, that using piston theory appears to correspond closest to the experiment. The influence of the viscous boundary layer on cylindrical shell flutter is reexamined. The boundary layer is modeled by a parallel shear flow, and the oscillating shell surface is approximated by an oscillating plane wall whose deflection is sinusoidal in both in-plane directions. Viscous effects are neglected with respect to flow perturbation quantities, nonlinear terms are neglected, and the final equations are integrated numerically through the boundary layer. It was found that, for the thicknesses of boundary layer present in the experiments, the resulting pressures on the oscillating wall are reasonably close to the corresponding potential theory ones. Hence, in that sense, the influence of the boundary layer appears to be negligible for shell flutter with many circumferential waves. Author
- Fluid Mechanics