Propfan supersonic panel method analysis and flutter predictions.

摘要

A supersonic panel method analysis for propfan performance and flutter predictions has been developed by extending Williams' three dimensional unsteady lifting surface theory to the supersonic speed range. The method upgrades the capability of the original (subsonic) panel code, UPROP3S, to include the propfan operating conditions at subsonic axial speeds with subsonic/supersonic tip speeds, and supersonic axial speeds. The original panel code, UPROP3S, is coded for the predictions of steady performance characteristics, forced vibration, static aeroelastic deformation, and flutter. This panel code is effective and inexpensive compared to full potential, Euler, or Navier-Stokes codes.;In this method the unsteady aerodynamic model is based on the three dimensional linearized compressible aerodynamic theory. A piecewise constant load paneling technique is applied to find the blade pressure difference distributions from the lifting surface integral equation. The aeroelastic model is formulated in terms of the in-vacuum normal modes of the blades. The flutter event is determined by solving the eigenvalue problem associated with the equations of motion.;The surveyed propfan wind tunnel models include the SR2, SR3, SR5, and SR7 blades. The computed results correlate very well with the measured data in both performance and flutter predictions. It is thought that the present study could also lead to the emergence of a supersonic cruise propeller.