Experimental Study on Impingement of Fuel Droplet on Substrates

Within a gasoline direct injection (GDI) engine, the impingement of fuel droplet on substrates induces various problems such as particular matter emission, oil dilution and abnormal combustion. Therefore, in order to solve these problems, it is urgent to have a clear understanding of the impingement behavior of fuel droplet impacting on substrates. Most previous studies have focused on the impingement of either water droplet on dry solid surface or the impinging droplet on the liquid film of the same type of liquid, while little research has been conducted on the impingement of fuel droplet on relevant substrates existing in GDI engines. The impingement of fuel droplet with higher Weber number on dry surface, fuel film and oil film with different thickness and viscosity were investigated experimentally. Results show that fuel droplet impacting on dry wall is easy to be deposited to form a fuel film. The fuel film attached to the wall is the main reason for the splash. The thickness of fuel film adhered to the dry wall affects the splash degree of secondary droplets. As the fuel droplet impacts on pure oil film of different thickness and viscosity, there is no secondary droplets spattering into the air. After collision, the fuel droplet together with the jet deposits into the oil film causes the oil dilution.