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This paper describes an experimental investigation into the surface heat transfer coefficient of finned metal cylinders in a free air stream. Ten 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 with an external cylinder diameter of 100mm and fin lengths of 10 to 50mm. The fins of each cylinder were gravity die cast in aluminium alloy. Each cylinder was electrically heated and mounted in a wind tunnel which subjected it 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. In addition to the determination of an overall heat transfer coefficient, the distribution of cooling around the circumference of each cylinder was also studied.

A numerical study of the heat transfer from an air-cooled single-cylinder engine has been undertaken using computational fluid dynamics. The variation in heat transfer from and airflow around the cylinder, which was simplified to a stack of annular fins, was observed at different values of fin pitch and length. The simulation results were compared with experimental results obtained previously at Queen's University Belfast (QUB). The CFD prediction of the circumferential temperature distributions had a similar trend to the experimental analysis, offset from the experimental results by approximately 8 degrees Kelvin.

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.

This paper describes the flow characteristics in the near throat region of a poppet valve under steady flow conditions. An experimental and theoretical procedure was undertaken to determine the total pressure at the assumed throat region of the valve, and also at a downstream location. Experiments of this type can be used to accurately determine the flow performance of a particular induction system. The static pressure recovery was calculated from the near throat region of the valve to the downstream location and was shown to be dependent on valve lift. Total pressure profiles suggest that for this particular induction system, the majority of pressure loss occurs downstream of the valve for lift/diameter ratios up to 0.1, and upstream of the valve for lift/diameter ratios greater than 0.1.