Experimental Investigation into the Free-Air Cooling of Air-Cooled Cylinders

David Thornhill, A. Graham, Geoffrey Cunningham, R. Meyer, P. Troxler

Research output: Contribution to journalArticlepeer-review


This paper describes an experimental investigation into the surface heat transfer coefficient of finned metal cylinders in a free air stream. Eight cast aluminium alloy cylinders were tested with four different fin pitches and five different fin lengths. The cylinders and their fins were designed to be representative of those found on a motorcycle engine. Each electrically heated cylinder was mounted in a wind tunnel and subjected to a range of air speeds between 2 and 20 m/s. The surface heat transfer coefficient, h, was found primarily to be a function of the air speed and the fin separation, with fin length having a lesser effect. The coefficient increases with airspeed and as the fins are separated or shortened. It was also noted that a limiting value of coefficient exists, influenced only by airspeed. Above the limiting value the surface heat transfer could not be increased by further separation of the fins or reduction in their length.
Original languageEnglish
Pages (from-to)2046-2057
Number of pages12
JournalSAE 2003 Transactions Journal of Engines
Volume112 (3)
Publication statusPublished - Sep 2004

Bibliographical note

Journal Name: 0768014506


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