High-Fidelity Simulations of Tip Vortex Impingement for Prediction of Blade Wake Interaction Noise

Abstract:
This paper presents an analytical prediction of rotor blade–wake interaction (BWI) noise using a newly developed turbulence intensity model. The new model is developed using high-fidelity computational fluid dynamics (CFD) results and is validated against experimental data for a BO105 rotor, showing good agreement. Compared to the Glegg model, the proposed approach predicts sound pressure levels approximately 3 dB higher at 600 Hz and about 2 dB higher below 800 Hz, highlighting the contribution of turbulence outside the vortex core. Furthermore, high-fidelity CFD simulations of tip vortex impingement on a downstream wing are performed using Large Eddy Simulation (LES), fully turbulent Improved Delayed Detached Eddy Simulation (SST-IDDES), and Gamma Transitional IDDES (GT-IDDES). Both LES and GT-IDDES capture detailed unsteady and boundary layer transitional flow features, whereas SST-IDDES fails to capture transition and produces a RANS-dominated, time-averaged flow field. The swirl motion of tip vortices is observed near the leading edge of the downstream wing during impingement, which progressively weakens over time. In the post-impingement phase, the results show that tip vortex interaction locally increases the effective angle of attack, leading to instantaneous leading-edge separation on the downstream wing.

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