Helicopter flight around a ship's' superstructure

Abstract

A computational fluid dynamics model of a hovering helicopter main rotor is developed to examine air flow in the presence of ship structures and side winds. An illustration of the problem is given. The rotor is modelled by modifying the governing Navier-Stokes equations in the region of the disc. The extra terms added to the governing equations apply a downward force to the fluid; these forces are independent of the flow around the rotor and are equal to the helicopter weight. The helicopter rotor model and the ship model are combined to yield one flow solution, which, due to the severe non-linearities of the problem, cannot be achieved by superposition. The resultant flow yields valuable data about the induced velocities at the rotor, which ultimately determine the control pitch and power required to maintain the hover in a given location. Indeed, the interactions between the rotor downwash and ship air flow are known to produce unexpected and adverse flight dynamic behaviour of the aircraft.