Subsonic/Transonic Stall Flutter Investigation of an Advanced Low Pressure Compressor

Abstract

The subsonic/transonic stall flutter characteristics of the Pratt & Whitney PW1120 Low Pressure Compressor (LPC), recently have been defined through fan rig tests and a full-scale engine test. Flutter data analyses, based on both empirical and analytical methods, have shown excellent correlations between test results and predictions. While the LPC was demonstrated to be flutter-free over its entire flight envelope, the study indicates the need for continued research in transonic unsteady aerodynamics, particularly, the effects of passage shocks and large leading edge incidence.

Stall flutter prediction techniques for fan and compressor blades

“…Examples of the application of this approach for stall flutter prediction can be found in Jeffers and Meece 18 and EL-Aini et al 19 The empirical technique, while valuable, does not explicitly include all of the physical parameters that influence stall flutter. For this reason, the purely empirical approach is the most successful for fan and compressor airfoils of similar configuration.…”

“…The semiempirical method has been used to successfully predict the flutter of high aspect ratio fan blades. 19 Recently, the semiempirical method was extended for stall flutter predictions of low aspect ratio blades. The semiempirical method had been previously used for beam modes where the vibratory deflection is specified as a rigid body translation and rotation, which is directly applicable to the form of the original experimental data.…”