Sanford Fleeter

Supersonic Inlet-Torsional Cascade Flutter

Currently there is a dearth of fundamental dynamic aeroelastic cascade data with which to validate and/or indicate necessary refinements in mathematical models of such phenomena. This paper describes a unique supersonic inlet with a subsonic axial component, torsional flutter cascade experiment, wherein a computer controlled electromagnetic airfoil excitation system is used to simulate the fundamental time-dependent airfoil interaction, assure physical periodicity, and control the interblade phasing angle. Experimental data are presented which indicate the variation and significance of the cascade inlet Mach number, the stagger angle, and, in particular, the interblade phasing angle on the cascade dynamic torsional aeroelastic characteristics.

Experimental Modeling of Unstalled Supersonic Turbofan Flutter

This paper describes the experimental techniques and procedures used to extend the current experimental unsteady rectilinear cascade modeling capability to include the relatively low supersonic inlet Mach number, high pressure ratios, and high reduced-frequency values characteristic of the unstalled supersonic flutter of fan stages. In particular, the cascade modeling concepts, the steady and time-variant experimental techniques, fabrication and instrumentation considerations, data acquisition and reduction procedures, and the correlation of the resulting steady and time-variant cascade data with corresponding predictions are presented.