Innovative Systems for Reduction of Rotorcraft Hub Drag

Recent applications of Active Flow Control (AFC) to fixed wing configurations demonstrated the efficacy of AFC in reducing drag. Substantial work was done using simple periodic actuation using zero-mass flux devices, however, novel devices that are light and have no moving parts but require compressed air became available and they have proven their effectiveness in some applications. The application of this knowledge to rotating systems such as the shank and a hub of a helicopter rotor represent the heart of the present proposal. In fact knowing the high drag of the rotor hub assembly led the PIs to acquire the experimental apparatus on which drag reduction schemes using AFC could be investigated. The facility is ready for initial tests and was awaiting sponsorship. The SBIR announcement provides such an opportunity. A generic three bladed rotor hub assembly was designed that can be rotated in a wind tunnel at free stream velocities ranging from 0 to 80miles/hour. The shanks are mounted on load cells that can measure their drag in addition to the overall drag of the assembly. The shanks are also equipped with actuators which should reduce the shank’s drag. Alternate actuation schemes may be investigated in the future.