The influence of the vortex impingement location on the aerodynamic and acoustic response of a rotating blade during an orthogonal interaction is studied by means of computational fluid dynamics. The objective is to identify and quantify precisely the noise reduction achieved by reducing the blade span. The Batchelor vortex model is primarily considered as it accounts for the axial velocity deficit observed in the core of realistic tip vortices. Separated simulations were also carried out for a Lamb–Oseen vortex and a purely axial velocity deficit to highlight and quantify the influence of the vortex velocity components on the interaction as well as to balance design optimizations performed relying on methods not able to model viscous effects. The analysis of the blade aerodynamic and acoustic responses shows that the magnitude of the thrust fluctuation and radiated noise are always higher for a Batchelor vortex than for a Lamb–Oseen vortex when the vortex core impinges below the blade tip. For both vortex models, the thrust fluctuation and radiated noise reach their peak for an interaction close to the blade tip. They decrease slowly as the vortex impingement moves inward the blade and decrease strongly as the vortex passes above the tip. Finally, the noise directivity pattern is dipolar for the interaction close to or above the blade tip and becomes more and more quadrupolar as the radius of the interaction moves toward the blade root.
Vortex Model and Blade Span Influence on Orthogonal Blade-Vortex Interaction Noise
AIAA Journal ; 58 , 8 ; 3405-3413
2020-08-01
Article (Journal)
Electronic Resource
English
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