Seperate Determination of Coexisting Components of Aerodynamic Drag on Rotors

Period of Performance: 03/04/1998 - 03/04/2000


Phase 2 SBIR

Recipient Firm

Applied Aero, LLC
48967 Ventura Drive
Fremont, CA 94539
Principal Investigator

Research Topics


The aerodynamic drag on the hovering rotor was decomposed into the profile drag, the induced drag, and the unsteady drag under the Phase I research. A wake-integral approach was used to express the profile drag and the induced drag as wake integrals. A viscous theory of aerodynamics was used to express the unsteady drag as an integral over the surface of the rotor blade. Using these integral expressions, the profile drag and the induced drag can be separately evaluated using wake-survey data. The unsteady drag can be evaluated using easily computed virtual inertia coefficients for any prescribed blade geometry. Theoretical, experimental, and computational research will be performed under the Phase II work to create engineering tools for reducing the drag on rotors in hover and in forward flight. The integral expressions for the drag components will be refined and expanded to include forward flight effects. A hybrid Navier-Stokes solver based on an integro-differential method and a vorticity-confinement method will be established for computing the flow in the rotor's near wake. Experiments will be performed to obtain benchmark wake-survey data and to establish guidelines for future validations of novel design concepts. BENEFITS: This research program will create a design technology for drag-reduction applications in a broad range of industries. Future design of rotorcraft will be directly impacted by this research. The technology will also benefit the design of fixed-wing aircraft, ground vehicles, marine vessels, windmills and other fluid machineries.