Sirignano worked on the
Saturn V Rocketdyne F-1 engine at NASA's
Marshall Space Flight Center while still a graduate student at Princeton. After completing his studies, he joined Princeton's faculty as a professor of mechanical and aerospace engineering from 1973 to 1979. He was also a research fellow at
United Aircraft in 1973. In 1979, he moved to
Carnegie Mellon University, where he served as the George Tallman Ladd Professor and head of the Department of Mechanical Engineering until 1984. He joined UCI in 1985 as dean of the
UC Irvine Samueli School of Engineering, a role he held until 1994. He helped the school develop an undergraduate degree in aerospace engineering. He returned full-time to research and teaching thereafter as a distinguished professor. Sirignano's earliest research was on oscillatory
pressure waves in
rocket engines, a phenomenon responsible for catastrophic failures in early rocket development. He developed
shock wave models of unstable combustors and theories for the nonlinear behavior of
Helmholtz resonators used as acoustic
dampers in combustion chambers. Sirignano also worked in spray combustion, developing theories of droplet
vaporization with
convective heating with applications in engine
injectors and
spray nozzles. In 1989, he developed the Abramzon–Sirignano model for droplet vaporization with Boris Abramzon, which became widely used in computational spray combustion. His research on the instability and atomization of thin liquid sheets and jets, addressing
Kelvin–Helmholtz instability,
capillary wave distortion,
vorticity dynamics, and droplet formation contributed to the analytical understanding of fuel atomization and his textbook on the topic has become a standard reference in the field. Together with fellow UCI professor Feng Liu, Sirignano pioneered the turbine-burner concept in 1999, in which a
combustor integrated directly into the turbine stages of a
gas turbine engine supports continuous near-constant-temperature combustion, achieving higher efficiency and
specific thrust than conventional designs. He also developed a miniature liquid-fuel film combustor concept for small scale propulsion. He also published research on combustion at supercritical and transcritical conditions,
flame spread across liquid and
solid fuel, turbulent combustion in reciprocating and
rotary internal combustion engines. He was appointed a fellow of the
American Institute of Aeronautics and Astronautics (AIAA) in 1987, the
American Society of Mechanical Engineers (ASME) in 1989, and the
American Association for the Advancement of Science in 1992. Notable past students include
Josette Bellan, a senior research scientist at NASA's
Jet Propulsion Laboratory,
Peyman Givi, a rocket scientist at the
State University of New York, and
Chung K. Law, the Robert H. Goddard Professor at
Princeton University. == Awards ==