Modelling characteristics of gasoline wall films in the intake port of port fuel injection engines

Abstract

Models were developed to describe the vaporization of well-mixed wall films of multi-component engine fuels based on continuous thermodynamics and applied to describing multi-component fuel spray-wall interactions. All the models were implemented into the KIVA3V Release 2.0 code. Validation calculations were conducted for pulsed injection cases and compared with experimental wall film thickness data under different air-fuel ratios and inflow conditions in an inclined pipe, which simulates an intake port of port fuel injection engines. Calculations with single-component iso-octane fuel were also conducted for comparison. The influence of wall temperature, inflow-air velocity and injection angle on the gasoline wall film characteristics was studied. The results indicate that the multi-component fuel film is composed of increasingly heavy species as the vaporization proceeds. The fuel-film structure which results from spray-pipe-wall interaction is greatly different from that resulting from spray-plane-wall interaction. An increase in the wall temperature significantly decreases both the film thickness and the film area. The injection angle significantly changes the wall film structure. Although the inflow velocity enhances the fuel vaporization rate, it has a relatively small effect on the fuel film movement along the pipe wall.

Optical investigations of fuel deposition burning in ported fuel injection (PFI) spark-ignition (SI) engine

“…For the same injection condition, the gasoline film was larger and present on valve surface for a longer time than iso-octane. Gasoline film was composed of increasingly heavier species as the vaporization proceeded [4,12]. In order to identify the chemical species occurring during the combustion processes, spectroscopic investigations of natural emissions were performed in different locations of the chamber.…”

“…Liquid fuel film forms in gasoline engines near the valves due to the impingement of the injected fuel spray on the intake manifold and on the ports' surfaces [1][2][3][4][5]. Once formed, the film develops dynamically under the influence of the gas flow and of the valve movement [1,2].…”

“…Once formed, the film develops dynamically under the influence of the gas flow and of the valve movement [1,2]. The heat exchange with port walls and with the surrounding gas leads to the fuel evaporation, affecting the composition of the mixture and hence the complexity of the flow and the combustion process [3][4][5]. In particular, liquid fuel vaporization and fire near the valves can reduce the flame speed and the complete flame propagation creating locally rich-zones.…”

Predictions of Transient Fuel Spray Phenomena in the Intake Port of a Si-Engine

“…7. By deposition of fuel on the valve surface a liquid wall film is generated [28], in particular for cold starting conditions. For the studied operating conditions, the surface temperature of the valve increases and is even exceeding 100 AE C (373 K) [14].…”