Abstract
Two mathematical models are used in this work to estimate the acoustics of a hovering main rotor. The first model is based on the Ffowcs Williams-Howkings equations using the formulation of Farassat. An analytical approach is followed for this model, to determine the thickness and load noise contributions of the rotor blade in hover. The second approach allows using URANS and RANS CFD solutions and based on numerical solution of the Ffowcs Williams-Howkings equations. The employed test cases correspond to a model rotor available at the KNRTU- KAI aerodynamics laboratory. The laboratory is equipped with a system of acoustic measurements, and comparisons between predictions and measurements are to be attempted as part of this work.
Highlights
There are two fundamental elements that contribute to the generation of near-field and far-field noise, themain rotor and the tail rotor [1]
The tonal noise is usually divided into the deterministic components of thickness and loading noise, blade-vortex interaction (BVI) noise [2] and high-speed impulsive noise
Broadband noise consists of the non-deterministic loading noise sources classified as turbulence ingestion noise, bladewake interaction noise and blade self-noise [3]
Summary
There are two fundamental elements that contribute to the generation of near-field and far-field noise, themain rotor and the tail rotor [1]. A helicopter main rotor generates primarily tonal and broadband noise. The tonal noise is usually divided into the deterministic components of thickness and loading noise, blade-vortex interaction (BVI) noise [2] and high-speed impulsive noise. The reason of thickness noise is the displacementof the fluid by the rotor blade and loading noise is caused by the accelerating force generated by moving blade surface. The term “loading noise” is usually a reference to the harmonic noise from non-impulsive loading sources, whereas impulsive loading noise due to blade-vortex interaction. The geometry of the rotor employed for theoretical analysis corresponds to the helicopter rig rotor of KNRTU-KAI aerodynamics laboratory. The main goal of this work is a preliminary research of the acoustics of the KNRTU-KAI rotor rig
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