Navier-Stokes analysis of helicopter rotor aerodynamics in hover and forward flight

Reynolds-averaged compressible Navier-Stokes computations are presented for the hovering 7A model rotor and a low aspect ratio NACA0012 rotor in nonlifting forward flight. For enhanced hover performance prediction, aeroelastic effects are taken into account by tightly coupling the flow solver with a finite element model of the blade based on Timoshenko beam theory; Good agreement between computed and measured rotor performance is achieved for three collective pitch settings on structured periodic grids featuring noncongruent cell faces along the periodicity planes. Results of a hybrid Navier-Stokes/Euler chimera hover computation are, resented, in addition to the periodic grid analysis demonstrating the superiority of the*overset grid approach with respect to tip vortex conservation. The unsteady Navier-Stokes computations for the nonlifting forward flight test case show more sensitivity relative to time step size than comparable Euler analyses. Overall correlation of computed and experimental near-tip pressure distributions overblade azimuth is considered to be fair, and the strong transonic effects on the advancing blade are adequately captured by the numerical analysis.