Argonne scientists peel away layers of dense liquid flow dynamics

Technique may lead to better, cleaner fuel injectors for automobiles

Standard microscopy and visible light imaging techniques cannot peer into the dark and murky centers of dense-liquid jets, which has hindered scientists in their quest for a full understanding of liquid breakup in devices such as automobile fuel injectors.

Scientists at the U.S. Department of Energy’s (DOE) Argonne National Laboratory have developed a technique to peer through high-speed dense liquids using high-energy X-rays from Argonne’s Advanced Photon Source (APS).

“The imaging contrast is crisp and we can do it orders of magnitude faster than ever before,” Argonne X-ray Science Division physicist Kamel Fezzaa said.

Fuel injector efficiency and clean combustion is dependent on the best mixture of the fuel and air. To improve injector design, it is critical to understand how fuel is atomized as it is injected. However, standard laser characterization techniques have been unsuccessful due to the high density of the fuel jet near the injector opening. Scientists have been forced to study the fuel far away from the nozzle and extrapolate its dispersal pattern. The resulting models of breakup are highly speculative, oversimplified and often not validated by experiments.

“Research in this area has been a predicament for some time, and there has been a great need for accurate experimental measurement,” Fezzaa said. “Now we can capture the internal structure of the jet and map its velocity with clarity and confidence, which wasn’t possible before.”

Fezzaa and his colleagues, along with collaborators from VisteonCorp. developed a new ultrafast synchrotron X-ray full-field phase contrast imaging technique and used it to reveal instantaneous velocity and internal structure of these optically dense sprays. This work is highlighted in the Advance Online Publication of the journal Nature Physics.