Hee Dong Lee/Dong Ok /Oh Joon Kwon/Hee Jung Kang
International Journal of Aeronautical and Space Sicences, vol. 12, no. 2, pp.190-199, 2011

Abstract : In the present study, unsteady flow simulations of complete helicopter configurations were conducted, and the flow fields and the aerodynamic interferences between main rotor, fuselage, and tail rotor were investigated. For these simulations, a three-dimensional flow solver based on unstructured meshes was used, coupled with an overset mesh technique to handle relative motion among those components. To validate the flow solver, calculations were made for a UH-60A complete helicopter configuration at high-speed and low-speed forward flight conditions, and the unsteady airloads on the main rotor blade were compared with available flight test data and other calculated results. The results showed that fuselage affects the main rotor blade airloads by changing the rotor inflow distribution, and that unsteady vibratory airloads are produced on the fuselage, which are nearly in-phase with the blade passage over the fuselage. The flow solver was then applied to the simulation of a generic complete helicopter configuration at various flight conditions, and the results were compared with those of the CAMRAD-II comprehensive analysis code. It was found that main rotor blades are in a strong interaction with a pair of disk-vortices at the outer edge of the rotor disk plane, which leads to high pulse airloads on the blade, and these airloads behave differently depending on the specific flight condition.

Keyword : Unsteady flow, Complete helicopter configuration, Aerodynamic interference