TY - JOUR
T1 - Impingement of a propeller-slipstream on a leading edge with a flow-permeable insert
T2 - A computational aeroacoustic study
AU - Avallone, Francesco
AU - Casalino, Damiano
AU - Ragni, Daniele
PY - 2018/11/1
Y1 - 2018/11/1
N2 - This manuscript describes an aeroacoustic computational study on the impingement of a tractor-propeller slipstream on the leading edge of a pylon. Both the flow and acoustic fields are studied for two pylon leading edges: a solid and a flow-permeable one. The computational set-up replicates experiments performed at Delft University of Technology. Computational results are validated against measurements. It is found that the installation of the flow-permeable leading-edge insert generates a thicker boundary layer on the retreating blade side of the pylon. This is caused by an aerodynamic asymmetry induced by the helicoidal motion of the propeller wake, which promotes a flow motion through the cavity from the advancing to the retreating blade side of the pylon. The flow-permeable leading-edge insert mitigates the amplitude of the surface pressure fluctuations only on the pylon-retreating blade side towards the trailing edge, thus reducing structure-borne noise. Furthermore, it causes a reduction of the near-field noise only for receiver angles oriented in the upstream direction at the pylon-retreating blade side. In this range of receiver angles, it is found that the flow-permeable leading-edge insert reduces the amplitude of the tonal peaks for the third and fourth blade passage frequency, but strongly increases the broadband noise for frequencies higher that the seventh blade passage frequency.
AB - This manuscript describes an aeroacoustic computational study on the impingement of a tractor-propeller slipstream on the leading edge of a pylon. Both the flow and acoustic fields are studied for two pylon leading edges: a solid and a flow-permeable one. The computational set-up replicates experiments performed at Delft University of Technology. Computational results are validated against measurements. It is found that the installation of the flow-permeable leading-edge insert generates a thicker boundary layer on the retreating blade side of the pylon. This is caused by an aerodynamic asymmetry induced by the helicoidal motion of the propeller wake, which promotes a flow motion through the cavity from the advancing to the retreating blade side of the pylon. The flow-permeable leading-edge insert mitigates the amplitude of the surface pressure fluctuations only on the pylon-retreating blade side towards the trailing edge, thus reducing structure-borne noise. Furthermore, it causes a reduction of the near-field noise only for receiver angles oriented in the upstream direction at the pylon-retreating blade side. In this range of receiver angles, it is found that the flow-permeable leading-edge insert reduces the amplitude of the tonal peaks for the third and fourth blade passage frequency, but strongly increases the broadband noise for frequencies higher that the seventh blade passage frequency.
KW - Flow-permeable leading edge
KW - tractor-propeller noise
KW - vortex-impingement noise
UR - http://www.scopus.com/inward/record.url?scp=85052216239&partnerID=8YFLogxK
U2 - 10.1177/1475472X18788961
DO - 10.1177/1475472X18788961
M3 - Article
SN - 1475-472X
VL - 17
SP - 687
EP - 711
JO - International Journal of Aeroacoustics
JF - International Journal of Aeroacoustics
IS - 6-8
ER -