An Adaptive Solution Procedure for Rotorcraft Aerodynamics

An adaptive refinement procedure is developed for computing vortical flows encountered in rotor aerodynamics. For this purpose, an error indicator based on interpolation error estimate is formulated and coded into an adaptive finite element framework. It is shown that the error indicator is effective in resolving the global features of the flow-field. Furthermore, for efficiency and problem size considerations, once the interpolation errors are reduced to acceptable levels, the adaptive refinement is done only in regions effected by vortical flows. To do this, a novel vortex core detection technique is used to capture vortex tubes. The combination of interpolation error estimate and vortex core detection technique proved to be very effective in computing vortical flow-field of rotor blades. Using this adaptive solution method two rotor systems, namely Caradonna-Tung and UH-60A BlackHawk, were analyzed in subsonic hover flow conditions. For these two rotors adaptively computed results are in close agreement with the experimental data.

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