Particle Image Velocimetry Investigation Of The Aerodynamic Interaction Between Helicopter And An Aircraft Carrier

Abstract

Helicopters greatly expand operational capabilities during military missions at the sea. The aircraft carriers are capable of accommodating fixed-wing and rotary-wing aircraft operations. They not only have one runway for take-off, but also have different spots for helicopter operations. As they are spread over the deck of the aircraft carrier, the non-aerodynamic geometries of the take-off ramp and the island can generate complex flows, with high velocity gradients and turbulence intensities that can make complex the helicopter landing and take-off maneuvers for pilots. This study analyses the interaction between the aerodynamic patterns generated by the warship and those generated during the operation of the helicopter. Two wind conditions are simulated: headwind and crosswind. The results are provided by a Particle Image Velocimetry (PIV) system installed at the wind tunnel test section of a low-speed wind tunnel. The model of aircraft carrier and helicopter are tested in a reduced scale of 1:100. And the helicopter rotor rotates at sufficient speed to ensure the similarity of the thrust coefficient with the real case. Finally, during the wind tunnel tests, using an automatic positioning system, the helicopter is placed in different positions above the aircraft carrier flight deck in order to obtain PIV images and extract non-dimensional velocity contours with and without the helicopter effect. The results have shown important effects of the aerodynamics generated by the bow, the hull and the aircraft carrier island, with velocity differences up to 70 % depending on the landing spot analyzed.