The Effect of Heat Transfer on the Steady Flow Through a Poppet Valve

A study was made to determine the effect of heat transfer from the backface of a poppet intake valve on the flow rate through the valve. All tests were made under steady flow conditions.

The results show that for the same lift and same pressure drop across the valve, the flow rate through a hot valve is less than through a cold valve. This effect increases almost linearly with the heat transfer rate and decreases rapidly with lift. The results also show that the effective flow area is independent of pressure drop through the valve.

A correlation of heat transfer from the back of the valve surface to the flowing air shows that the Nusselt number varies as the 1.27 power of the Reynolds number.