True-scale True-pressure Internal Flow Visualization for Diesel Injectors

Experimentation and computation show that the tilted orifice common in some Diesel fuel injectors sometimes functions similar to a swirl atomizer. In this paper the internal fluid dynamics, including different instances of cavitation, are examined. The authors and others around the world have shown that cavitation at the inlet to the orifice aids in the creation of desired sprays. Because of the complexity of this unsteady, two-phase flow with non-equilibrium bubble dynamics, true scale and true pressure are used for flow visualization. Thus, the cavitation inside tilted 200 micron spray holes at pressures up to 210 MPa (2,000 atmospheres) is imaged.