Parametric Trends in the Flutter of Advanced Turboprops

Abstract

The parametric trends in the aeroelastic behavior of an advanced turboprop were experimentally investigated using a subvelocity-scaled testing procedure. A 2-ft-dia subvelocity-scaled model was constructed and its flutter behavior was favorably correlated to that of a full-velocity-scaled UnDucted Fan™ model for which aflutter point had been documented. With the validity of the subvelocity-scaled procedure established, the inherent versatility was exploited through the construction and flutter testing of models which allowed for the parametric variation of sweep, mass distribution, and solidity. The correlation between an analytic model developed and the experiment is favorable for variation in mass distribution and sweep. As is typical of moderate mass ratio wings and blades, the flutter was found to be of a coalescence type, the onset of which is determined by a critical relative velocity with a slight dependence on loading and cascade effects.