A Method for Predicting the Aerodynamic Loads and Dynamic Response of the Rotor Blades of a Tandem-Rotor Helicopter

摘要

The blades of each rotor are represented by segmented lifting lines located at the quarterchord positions of the blades and the vortex strength is assumed to be constant over each segment of the blade at each of an arbitrary number of azimuth positions. The wake is represented by a mesh of shed and trailing vortex filaments up to an arbitrary finite distance behind each blade, and beyond this point the wake is represented by a segmented, tip-trailing vortex or by segmented, tip- and root-trailing vortices. The aerodynamic loadings and the flapwise structural bending moments were computed for the CH 47A tandem-rotor helicopter for advance ratios of 0.08, 0.14 and 0.24. Comparisons of these results with measured results for individual test points are presented as radial distributions of the first three harmonic components and as time histories which include eleven harmonics. The measured data were generally presented in the form of typical results from a statistical sampling of measured data from similar test conditions. (Author)