Alleviation of Propeller-Slipstream-Induced Unsteady Pylon Loading by a Flow-Permeable Leading Edge

Abstract

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Rapid distortion theory of turbulent flow around a porous cylinder

“…2019; Sinnige et al. 2019; Zamponi et al. 2019; Bampanis & Roger 2020) and theoretical (Ayton & Paruchuri 2019; Priddin et al.…”

Assessment of the accuracy of microphone array methods for aeroacoustic measurements

“…Phased microphone arrays have become one of the main measurement devices for studying aeroacoustic noise sources [1], such as aircraft [2][3][4][5][6][7][8][9][10][11][12], wind turbine blades [13][14][15][16][17][18][19], and rotating machinery [20][21][22]. In combination with acoustic imaging algorithms [1,23], phased microphone arrays provide estimates of the location and strength of sound sources [24,25].…”

Permeable Leading Edges for Airfoil and Fan Noise Reduction in Disturbed Inflow

“…Furthermore, such flow through the pores leads to an increase of the airfoil boundary-layer thickness, which has two effects: first, it effectively increases the airfoil thickness, which is generally known to be beneficial regarding the reduction of turbulence interaction noise [64]. Second, the increased boundary-layer thickness leads to a shift of the vortices away from the airfoil, and hence to a reduction of the pressure fluctuations induced by these vortices on the airfoil surface [16]. In addition, when the viscous eddies contained in the turbulent inflow interact with the small jets generated by the flow through the pores, additional turbulent kinetic energy will be dissipated.…”

“…With the aim of reducing the turbulence interaction noise, different leading-edge modifications have been developed in the past that affect the aerodynamic and acoustic properties of the airfoil. For isolated airfoils or flat plates, these modifications basically consist of leading-edge serrations [4][5][6][7][8][9][10], comblike structures [11], and the application of flow-permeable or porous materials [12][13][14][15][16][17][18][19]. Noise reduction techniques such as serrations or porous materials have also been used in so-called rod-airfoil configurations, which are used to study rotor-stator interaction noise [20][21][22][23].…”