An Experimental formulation for PFI injector penetration length versus time and pressure using high speed spray imaging results

Recently, there have been problems with particulate matter pollution in diesel engines and it has reduced production rate of these engines and also, it has accelerated the development of new technologies for PFI and GDI gasoline engines. The spray characteristics has significant impact on the combustion efficiency, power and emissions on internal combustion engines. In This study, effect of injection pressure on the fuel spray penetration, spray cone angle and separation angle has been investigated for EF7 bi fuel engine and an experimental formulation for spray penetration was introduced. The method of Schlieren Imaging method was used to obtain the geometric characteristics of the fuel spray. The images were processed in MATLAB software and the penetration, cone angle and spray separation angle as geometrical properties were calculated. The Otsu method was used to obtain an appropriate edge threshold of image. Investigation of the injection pressure effect on the penetration concluded an experimental formulation for penetration versus time and injection pressure. This equation was linear according to time and square root of injection pressure with maximum error of 8.4%. The penetration of the two fuel sprays (for both injectors tested) had a little difference at the similar pressures and injection times. It was concluded also the cone angle and spray separation angle increased with increasing injection pressure.