Alan Duong, Ph.D.
Education: Bachelor of Science in mechanical engineering (May 2015)
Doctor of Philosophy in aerospace engineering from the University of Notre Dame
McNair Project: Optical Flow Measurement of Cavitation in a Converging-Diverging Nozzle (2014)
Mentor: B. Terry Beck, Ph.D.
Cavitation is a phenomenon where liquids will vaporize when subjected to low pressures. Essentially, the pressure is reduced sufficiently such that the liquid boils at the given temperature. The highest pressure at which cavitation could occur is called the vapor pressure. However, the pressure associated with the onset of cavitation could be lower than the vapor pressure. This indicates the liquid exists under a meta-stable condition. The cavitation pressure can be significantly below the vapor pressure and the lowest pressure at which cavitation onset could occur is called the spinodal pressure. Cavitation can occur in external flow, such as flow around hydrofoils and propeller blades, and internal flow, such as capillary tubes and nozzles. For the present research a converging-diverging nozzle was chosen for analysis. There has been little to no research done on the detailed flow characteristics of cavitating liquids near the onset of cavitation in nozzles. The main objectives are to obtain measurements of both overall flow as well as more detailed velocity profile characteristics of cavitation onset in a converging-diverging nozzle using high-speed imagery and particle image velocimetry (PIV). The experimental set-up places the nozzle oriented vertically between two reservoirs. The upstream reservoir supplies liquid water flow entering the nozzle and is open to the atmosphere while the downstream reservoir is partially evacuated. The main region of study is the vicinity of the throat, near where the pressure is a minimum and cavitation onset occurs. This work provides support for on-going analysis of cavitation in converging-diverging nozzle flow.