A hybrid Navier Stokes/vortex particle wake methodology for modeling helicopter rotors in forward flight and maneuvers
Battey, Luke Sterling
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Maneuvering flight and high-speed flight are critical design points in any rotorcraft’s operating envelope. These conditions give complex flow phenomena, creating high stresses and vibrations. To accurately predict the flow properties over the relatively flexible rotor blades, coupling between computational fluid dynamics (CFD) and computational structural dynamics (CSD) is required. In this work, GT-Hybrid, a hybrid wake rotorcraft CFD code that is coupled to DYMORE, is used. A vortex particle method has been implemented, in place of the existing lattice wake methodology, that has been anticipated to better emulate a convecting wake of a rotor while providing some computational benefits. Several UH-60A flight conditions, including high-speed steady level flight as well as diving-turn and pull-up maneuvers, are simulated using the vortex particle method. Results are compared with those using the traditional wake method and available experimental data both qualitatively and quantifiably. The quantifiable comparison, which consists of a linear regression analysis, shows the vortex particle method improves prediction accuracy for maneuvers and has only minor effects on steady forward flight when compared to the lattice method results. Additionally, computational efficiency is improved by using the vortex particle method and time savings exist in every simulation.