Visualization of cavitation in high-pressure diesel fuel injector orifices

Modern diesel fuel injectors operate at pressures of up to similar to 200 MPa. Cavitation of the liquid fuel inside of injector orfices has long been known to occur because of structural damage to the orifice walls. Yet few visualizations of this economically important flow exist. The first true-scale, true-pressure visualizations in tilled holes are presented and discussed. True-pressure and true-scale experiments are necessary as scaling of these unsteady, nonequilibrium cavitating flows is present v impossible. The extreme pressure and the small size of these unsteady two-phase internal flows present challenges for flow visualization. Nevertheless, successful experiment design and visualization of the unsteady two-phase flow inside of true-scale tilted diesel injector holes as small as 200 mu m diameter and at pressures up to 220 MPa are presented.