TY  - JOUR
A1  - Swanepoel, Pieter Coenraad
A1  - Biedermann, Till M.
A1  - van der Spuy, Sybrand J
T1  - Experimental noise reduction (aeroacoustical enhancement) of a large diameter axial flow cooling fan through a reduction in blade tip clearance
T2  - International Journal of Aeroacoustics
N2  - Aerodynamic and aeroacoustic performance experiments were carried out on four- and eight bladed, 1.542 m diameter, axial flow cooling fans, with constant solidity and hub-to-tip ratio. Tests were conducted in an ISO5801, Type A Fan Test facility. The tip gap (TG) was reduced from 4 mm (0.26% fan diameter) to 2 mm (0.13% fan diameter), to 0 mm, for both fan configurations. The noise profile of each fan configuration at the same TG over the whole volumetric flow rate spectrum was compared to each other. The 4 mm (0.26%) TG is used as a baseline to measure the nett increase or decrease in sound levels. Noise emissions decreased as the TG was reduced. It is discovered that the four bladed fan configuration had lower noise emissions than the eight bladed fan configuration at all blade tip clearances at design flow rate. It is concluded that reducing the TG and number of blades, at constant solidity, reduces sound emissions. The 0 mm TG for the four bladed fan produced the greatest reduction in noise emissions. An increase in fan total-to-static performance is observed when reducing the TG for both fan configurations.
KW  - Axial fan design
KW  - aeroacoustics
KW  - blade passing frequency
KW  - tip clearance noise
KW  - fan noise
Y1  - 2023
UR  - https://opus4.kobv.de/opus4-ohm/frontdoor/index/index/docId/2081
SN  - 1475-472X
VL  - 22
IS  - 3-4
SP  - 210
EP  - 237
PB  - SAGE Publications
ER  -