Measurement and simulation of wall-wetted fuel film thickness

In gasoline engines, the quality of fuel mixture preparation in the intake has a strong influence on the performance and exhaust emission. This paper deals with the basic research on the fuel mixture preparation process, and reports the experimental and numerical investigations on characteristics of the wall-wetted fuel film. In the experiments, iso-octane mixed with 3-pentanone was injected against a flat wall. The film thickness on the wall was measured by using laser induced fluorescence (LIF) technique. The film area was measured with CCD camera. Influences of the injection duration, the impingement distance, and the impingement angle on the film thickness, film length, and film area are discussed. In the numerical simulation, the commercial computational fluid dynamics (CFD) software FLUENT was used. The results show that, in the radial direction, the film thickness increases to a peak around the impingement center and then decreases eventually reaching zero at the external edge. Enlarging the injection duration could expand the film area and make the fuel film thicker. As the impingement distance gets farther, the fuel film becomes thinner, and the film area becomes smaller. Minishing the impingement angle could expand the area of the thick part of the fuel film and meanwhile make the maximum film thickness smaller.