Vortex Shedding Control behind Helicopter Rotor Blades, using Thin Oscillating Plates- Application to Helicopter Noise Reduction

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Mohseni, Mohammad Hassan | 2017

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 50325 (45)
University: Sharif University of Technology
Department: Aerospace Engineering
Advisor(s): Javadi, Khodayar
Abstract:
The interaction of the vortices and helicopter’s blades is the most significant source of generating the main rotor’s noise, especially in landing and rising. The kind of this noise is broadband and it is produced because of establishing the vortices behind the forward blade, their interaction with backward blade, changing their structures and creating turbulency loading. The known method for modeling of the interaction of the vortices structures and solid surfaces is the simple compounding the rod and airfoil. In this project, by using this method, the noise of the interaction of vortex and blade is modeled in the Reynolds number of 48000 with LES and FW-H Analogy as a hibrid method in aeroacoustic. Numerical results are validated with Jacob's experimental data. Furthermore, with installing the oscillating plates on the rod as a method for controlling the vortex shedding behind the helicopter blades and reducing the noise of the interaction of vortex and blade, their effects are investigated. Results show the 1.63 dB reduction in maximum sound pressure level and 5.5 dB reduction in overall sound pressure level, respectively
Keywords:
Large Eddy Simulation (LES) ; Rod-Airfoil Model ; Aeroacoustics Waves ; Vortex Shedding ; Rotor Blade ; Blade-Vortex Interaction (BVI)

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