Experimental and Computational Study of the Interaction Between a Tandem-Rotor Helicopter and a Ship

The aerodynamic interaction between a tandem-rotor helicopter and an amphibious assault ship is investigated experimentally and computationally. The experiment was conducted in the Army 7- by 10-Ft Wind Tunnel at NASA Ames Research Center. Particle Image Velocimitry (PIV) was used to acquire 3-component velocity field measurements of the combined wake of the tandem-rotor helicopter and ship. The measured velocity fields are compared with calculations from the unsteady, incompressible flow solver Rot3DC. The Rot3DC simulation closely modeled the experimental installation, including wind tunnel walls. Comparisons are made for an equivalent full-scale wind speed of 35 knots, model yaw angle of - degrees, and different positions of the tandem-rotor helicopter. Comparisons between measured and calculated velocities are good, demonstrating the potential of Rot3DC in providing airwake information complementing the measured test matrix.