X선 위상차 가시화 기법을 이용한 GDI 인젝터 노즐 근방의 분무 간 상호간섭 해석

• Published in: 한국분무공학회지 Vol. 25; no. 2; pp. 60 - 67
• Main Authors: 배규한, Gyuhan Bae, 문석수, Seoksu Moon
• Format: Journal Article
• Language: Korean
• Published: 한국분무공학회 30.06.2020
• Subjects: Droplet size; Droplet velocity; GDI injector; GDI 인젝터; Spray collapse; X-ray phase contrast imaging; X선 위상차 가시화; 기계공학; 분무붕괴; 입자속도; 입자크기; X; GDI
• ISSN: 1226-2277; 2288-9051

Despite its benefit in engine thermal efficiency, gasoline-direct-injection (GDI) engines generate substantial particulate matter (PM) emissions compared to conventional port-fuel-injection (PFI) engines. One of the reasons for this is that the spray collapse caused by the spray-to-spray interaction forms the locally rich fuel-air mixture and increases the fuel wall film. Previous studies have investigated the spray collapse phenomenon through the macroscopic observation of spray behavior using laser optical techniques, but it is somewhat difficult to understand the interaction between sprays that is initiated in the nearnozzle region within 10 mm from the nozzle exit. In this study, the spray structure, droplet size and velocity data were obtained using an X-ray imaging technique from the near-nozzle to the downstream of the spray to investigate the spray-tospray interaction and discuss the effects of spray collapse on local droplet size and velocity distribution. It was found that as the ambient density increases, the spray collapse was promoted due to the intensified spray-to-spray interaction, thereby increasing the local droplet size and velocity from the near-nozzle region as a result of droplet collision/coalescence.