An experimental study on flat-wall-impinging spray of microhole nozzles under ultra-high injection pressures

The objective of the study is to provide information on the spray and mixture formation process of the microhole nozzle (d = 0.08 mm) under an ultra-high injection pressure (P-inj = 300 MPa). Flat-wall-impinging sprays were focused on and the laser absorption-scattering technique was adopted to obtain qualitative and quantitative information under various conditions. The spray and mixture characteristics of the conventional nozzle and microhole nozzles were compared; the advantages and disadvantages of microhole nozzles under different conditions were also discussed. Spray tip penetration length data were collected and compared with the predicted values using the gas jet theory. The results showed that the combination of the microhole nozzle and ultra-high injection pressure was very effective for obtaining the optimal penetration length, fast vaporization, and a high air entrainment rate.