The flow of diesel fuel through multi-hole injection nozzles is well understood. There are, however, no comprehensive experimental results for the design of injection nozzles for alternate fuels.
A steady state flow generator was designed and employed to analyze the effects of the physical fuel properties and the needle lift on the discharge coefficient for the nozzle orifice. Three fuels were tested: diesel reference fuel, a 50/50 mixture of diesel fuel and sunflower oil, and 100%. sunflower oil. The fuel viscosities range from 3.0 cS to 30.0 cS at 40°C. Five injection pressures ranging from 3.5 to 13.8 MPa, and eight increments of needle lift between 0.031 and 0.940 mm were used in this investigation.
A significant influence of needle lift, injection nozzle pressure, and physical properties of fuels on the flow coefficient in the normal operating range of a typical diesel engine was proven. Information necessary to establish the onset of turbulent motion for the flow through the injection nozzle can be determined, for the tested fuels, from the experimental results.