2081 2023 2023 eng 210 237 28 3-4 22 article SAGE Publications 1 -- 2023-06-08 -- 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. International Journal of Aeroacoustics 1475-472X 10.1177/1475472X231183156 true {"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2023,7,11]],"date-time":"2023-07-11T04:25:35Z","timestamp":1689049535318},"reference-count":34,"publisher":"SAGE Publications","issue":"3-4","license":[{"start":{"date-parts":[[2023,6,1]],"date-time":"2023-06-01T00:00:00Z","timestamp":1685577600000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["International Journal of Aeroacoustics"],"published-print":{"date-parts":[[2023,6]]},"abstract":"<jats:p> Aerodynamic and aeroacoustic performance experiments were carried out on four- and eight bladed, 1.542\u00a0m 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\u00a0mm (0.26% fan diameter) to 2\u00a0mm (0.13% fan diameter), to 0\u00a0mm, 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\u00a0mm (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\u00a0mm 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. <\/jats:p>","DOI":"10.1177\/1475472x231183156","type":"journal-article","created":{"date-parts":[[2023,6,8]],"date-time":"2023-06-08T20:42:20Z","timestamp":1686256940000},"page":"210-237","update-policy":"http:\/\/dx.doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":0,"title":["Experimental noise reduction (aeroacoustical enhancement) of a large diameter axial flow cooling fan through a reduction in blade tip clearance"],"prefix":"10.1177","volume":"22","author":[{"given":"Pieter Coenraad","family":"Swanepoel","sequence":"first","affiliation":[{"name":"Solar Thermal Energy Research Group (STERG), Department of Mechanical and Mechatronic Engineering, Stellenbosch University, Stellenbosch, South Africa"}]},{"given":"Till M","family":"Biedermann","sequence":"additional","affiliation":[{"name":"Institute of Sound and Vibration Engineering (ISAVE), Hochschule D\u00fcsseldorf University of Applied Sciences, Dusseldorf, Germany"}]},{"given":"Sybrand J","family":"van der Spuy","sequence":"additional","affiliation":[{"name":"Solar Thermal Energy Research Group (STERG), Department of Mechanical and Mechatronic Engineering, Stellenbosch University, Stellenbosch, South Africa"}]}],"member":"179","published-online":{"date-parts":[[2023,6,8]]},"reference":[{"key":"bibr1-1475472X231183156","volume-title":"The design of an axial flow fan for air-cooled heat exchanger applications","author":"Wilkinson MB","year":"2017"},{"key":"bibr2-1475472X231183156","doi-asserted-by":"publisher","DOI":"10.3397\/1.3151851"},{"key":"bibr3-1475472X231183156","unstructured":"Whittaker A. 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Biedermann Sybrand J van der Spuy eng uncontrolled Axial fan design eng uncontrolled aeroacoustics eng uncontrolled blade passing frequency eng uncontrolled tip clearance noise eng uncontrolled fan noise Fakultät Maschinenbau und Versorgungstechnik Energie & Ressourcen