The Occurrence of Flash Boiling in a Port Injected Gasoline Engine

The occurrence of flash boiling in the fuel spray of a Port Fuel Injected (PFI) spark ignition engine has been observed and photographed during normal automotive vehicle operating conditions. The flash boiling of the PFI spray has a dramatic affect on the fuel spray characteristics such as droplet size and spray cone angle which can affect engine transient response, intake valve temperature and possibly hydrocarbon emissions. A new method of correlating the spray behavior using the equilibrium vapor/liquid (V/L) volume ratio of the fuel at the measured fuel temperature and manifold pressure is introduced.