Paper 2: Experiments on a Model Simulating Heat Transfer between the Inlet Valve of a Reciprocating Engine and the Entering Stream

The experiments described in this paper are intended to show the approximate magnitude of heat transfer rates between a poppet-type inlet valve and the fluid flowing through it. A model inlet valve, containing an electric heating element, was placed in a short, straight, concentric duct and discharged into a larger, concentric cylinder. Heat transfer rate measurements suggest an increase of Nusselt number proportionate to the 0·6 power of the Reynolds number—the constant of proportionality depending on the valve lift. Calculations show that the effect of this heat transfer on volumetric efficiency is no more than 1 or 2 per cent, and the effect on the temperature reached by an inlet valve in a running engine is also of minor importance compared with those of heat transfer from the gases in the cylinder and of conduction to the seat and guide.