In a combustion environment, system instabilities and dynamic responses of components can have a major influence on performance, emissions, and product life. One of the key components in a combustion system are the fuel injectors which utilize instabilities to generate a well atomized fuel spray. In this work, a pressure-swirl atomizer was studied under steady state operation and oscillating pressure differential conditions to simulate a dynamic system input to the atomizer. Atomizer spray with and without the addition of a pre-filming surface was evaluated to determine the influence that a pre-filming surface has on the dynamic response of the liquid sheet near the atomizer exit. High-speed video was utilized to capture the response of the liquid sheet and quantify the instability. It was found that under steady state operating conditions, the pre-filming surface increased the atomizer flow number and discharge coefficient. When comparing spray edge variation, the atomizer without a pre-filming surface demonstrated an increasing spray edge variation with increasing pressure while the opposite trend was observed in the atomizer with a pre-filming surface. Under conditions with an oscillating pressure differential, additional spray edge variation was observed near field of the atomizer exit but was nonexistent further downstream indicating that the superposition of the fluid from pressure oscillation dissipated as it moved further from the atomizer exit and did not have an impact on wave growth in the liquid sheet.

Library of Congress Subject Headings

Automobiles--Motors--Fuel injection systems; Atomization; Spray combustion; Spray nozzles--Fluid dynamics

Publication Date


Document Type


Student Type


Degree Name

Mechanical Engineering (MS)

Department, Program, or Center

Mechanical Engineering (KGCOE)


Steven Day

Advisor/Committee Member

Michael Schertzer

Advisor/Committee Member

Jennifer O'Neil


RIT – Main Campus

Plan Codes