Aerodynamic noise generation in a rod-airfoil problem

Bruno Backes¹; William Roberto Wolf¹

¹ Universidade Estadual de Campinas

doi:10.20906/CPS/COB-2015-0103

Resumo

The present work concerns the study of aerodynamic noise generation and propagation from an airfoil immersed in a vortex wake. This investigation is of paramount importance for the design of aerodynamic configurations such as wing and high-lift devices as well as gas turbines and wind turbine blades, fans and propellers. In take-off and landing configurations, vortical structures from slat and wing impinge on the leading edges of wing and flap, respectively. In rotating configurations such as wind turbines, helicopter blades, industrial fans and propellers, the wake generated from the airfoil impinges on its own leading edge. The current research consists of an investigation of the physical mechanisms of airfoil noise generation due to vortex wakes generated from a cylinder placed upstream of an airfoil. This simplified flow configuration allows a parametric study of noise sources from airfoil leading edges. It must be mentioned that, in this problem, the presence of additional noise sources are also considered in the analysis. For example, one should mention the noise generated from the unsteady loading along the cylinder surface and from the airfoil trailing edge, beyond the noise from quadrupole-type sources present in the aerodynamic wakes from both geometries. The flow compressibility effects, cylinder positioning upstream of the airfoil and the ratio between vortex length and leading edge radius of curvature will be investigated. Direct Numerical Simulation (DNS) is the numerical method of choice to simulate the present flows of interest since it captures all the energy scales associated with noise generation and propagation. The aeroacoustic calculations will be performed using DNS and the Ffowcs Williams & Hawking (FWH) acoustic analogy formulation.

Palavras-chave: Acoustics; CFD; Aerodynamics; Leading Edge Noise