Insights into the spray impingement process from a gasoline direct injection fuel system fuelled with gasoline and ethanol

Particulate Matter (PM) emissions have a negative impact on both climate change and human health. To control PM emissions emitted by vehicles with the Gasoline Direct Injection (GDI) fuel system, increasing fuel injection pressure is being developed as a practical approach. In this paper, an experimental and numerical study was presented to thoroughly explore the entire development process of gasoline and ethanol impingement spray from a GDI injector under injection pressure of 10 MPa and 50 MPa. The results demonstrate that more droplets are predicted to distribute in the splash region with the increase of injection pressure (𝑃𝐼 ) from 10 MPa to 50 MPa, which helps improve air-fuel mixing quality and reduce PM emissions. The splash probability of gasoline droplets is about two percent higher than ethanol. By increasing 𝑃𝐼 from 10 MPa to 50 MPa, droplets with higher absolute normal velocity would promote the growth of impingement spray. The probability curves of droplet diameter are more concentrated in the smaller size range. Besides, the probability of relatively large droplets of gasoline is slightly lower than that of ethanol. Regarding the fuel film distribution, more folds and bulges can be seen at the boundary of fuel film with the 𝑃𝐼 increase to 50 MPa. Meantime, the film distribution becomes more scattered, which would benefit the homogeneity of air-fuel mixture. The film distribution area and boundary irregularity of gasoline are greater than those of ethanol, further promoting a homogeneous air-fuel mixture.