| The fuel economy improvement, potentially up to 30%, is the main driving force behind the research and development push toward the DISI (Direct Injection Spark Ignition) engines by automotive industry. The researches in past have focused on the spray impingement in diesel engines and PFI engines, but there is very few experimental work on high-pressure gasoline spray wall interactions for DISI engines. Thus, fundamental study of the spray impingement is performed to more fully understand these complex processes.; Two DISI hollow cone swirl injectors, having 20° and 60° cone angle, are used to impinge on an aluminum plate at both ambient (23 ± 2°C) and elevated temperature (95 ± 5°C) conditions. Ambient pressure is adjusted to 101, 335, 470 kPa(absolute), to simulate DISI engine conditions at various stages and three different impact angles (45°, 60°, 90°) are chosen. Various visualization and analysis techniques are used in experimental part of this thesis. Experimental works include high-speed macro and microscopic visualization, shadowgraphy and Particle Motion Analysis System (PMAS), and footprint visualization and Phase Doppler Particle Analysis (PDPA). Computational approach section includes the KIVA code and its implementation according to the impingement behavior.; Visualization results show the slight difference in overall spray behaviors, such as penetration and spread rate, according to temperatures and impact angles, and individual droplet impingement behaviors including splash. Shadowgraph results show the faster horizontal vapor phase propagation characteristics. Footprint results show the strong dependency of temperature and pressure on film evaporation rate and impingement patterns, and indicate air entrainment effects on oblique angle impingement. PDPA results show the quantitative droplet impingement behaviors. Weber numbers are calculated based on the PDPA results and compared with computational results. Splash and rebound subroutines are incorporated into KIVA-3V to simulate the impingement process. |
