(Dr. Ben Zinn, advisor)

"Study of an Internally Mixed Liquid Injector for Active Control of Atomization Process"

Abstract

 This document describes an experimental and theoretical investigation of an internally mixed air assisted liquid injector. The primary objective of this research is to develop a better liquid atomizer that could be actively controlled to provide a fuel spray with desired properties over a wide range of operating conditions of airborne gas turbine engines. Such an injector would overcome the shortcomings of the state of the art pressure and air-blast atomizers that produce poor sprays during part load operating conditions, i.e., startup and idling. To attain the goals of this study, the investigated injector would require capabilities for independent control of the fuel flow rate and spray properties, e.g., droplet diameters and trajectories, over the entire range of engine operating conditions. Such capabilities would permit optimization of the combustor performance in terms of, e.g., ignition, flame stability, combustor stability, efficiency and emissions. This research consists of a thorough study of the fluid dynamics and atomization process that will enable us to better understand the physics of atomization induced by two-phase flow of liquid and gas through an internally mixed air assisted injector. The aim of the experimental efforts is to show the controllability of the proposed injector and to identify the control variables. In support of the experimental studies, an analytical model is being developed to model the physical processes governing the operation of an internally mixed atomizer. The developed model can be used as a control tool to predict the flow and spray properties corresponding to specified operating conditions and to design better injectors. Although this research is focused on developing an injector for airborne gas turbine applications, it can be used in various industrial applications involving generation of liquid sprays, e.g., spray painting, spray drying, drug delivery etc.