HIGH LIFT CIRCULATION CONTROLLED HELICOPTER BLADE

摘要

Circulation control techniques have a long history ofrnapplications to fixed wing aircraft. General aviation has usedrncirculation control to delay flow separation and increase thernmaximum lift coefficient achievable with a given airfoil.rnThese techniques have been gradually expanded to otherrnapplications, such as ground vehicles, to reduce drag.rnCirculation control technology can, potentially, be appliedrnalso to each blade of the main rotor in a helicopter, in order tornincrease the lift capacity of the rotor. Applications ofrncirculation control technologies to fixed wing aircraft haverndemonstrated the potential of a three-fold increase in the liftrncoefficient, as compared to a conventional airfoil. Thisrnfinding would suggest that a rotorcraft equipped withrncirculation control of the main rotor blades could,rnconceivably, lift up a payload that is approximately threerntimes heavier than the maximum lift capacity of the samernhelicopter without circulation control. Alternatively,rncirculation control could reduce the required rotor diameter byrnup to 48%, if the maximum lift capacity remains unaltered.rnA High Lift, Circulation Controlled Helicopter Blade will be undergoing initial testing in the subsonic wind tunnel facility at West Virginia University. Two-dimensional elliptic airfoil models with air blowing slots for circulation control will bernused as specimens in these tests in order to determine the aerodynamic changes, especially in lift and drag forces, achievable with various blowing slot configurations. Based on the results of the wind tunnel testing, an improved, detailed design will be developed for the entire main rotor of a helicopter with circulation control.