M.Sc Thesis

M.Sc StudentTenenbaum Jonathan
SubjectAn Analytical Model of a Two-Phase Jet with Application to
Fuel Sprays in Internal Combustion Engines
DepartmentDepartment of Mechanical Engineering
Supervisors PROFESSOR EMERITUS Michael Shapiro
ASSOCIATE PROF. Leonid Tartakovsky
Full Thesis textFull thesis text - English Version


Two-phase jets are found in a variety of applications, including ink-jet printers, spray cooling, etc. Fuel sprays in internal combustion engines is an application of particular interest because of its direct influence on engine performance, energy efficiency and pollutants formation. Many phenomenological models have been proposed to quantify the temporal behavior of spray properties such as spray penetration with time, spray dispersion angle and cross-sectional averaged fuel concentration. However, most of the existing models have the limitation of providing a one-dimensional description and are thus unable to adequately describe the spatial point-wise spray distribution, in particular the local fuel concentration and mixture velocity.

The aim of this study is to develop a more elaborate spray model which allows for calculation of spatial local fuel concentration and mixture velocity. The model is based on the single-phase steady-state laminar axisymmetric jet flow field solution by Schlichting, which is applied for a two-phase jet in the limit of dilute fuel concentration. This solution is used to formulate and solve the problem of fuel concentration distribution in the stagnant air of the combustion chamber. This solution is also extended to turbulent jet flow in accordance with the model described by Schlichting and in other studies, and applied to predict point-wise spray properties of typical fuel sprays in internal combustion engines.

The results are compared with the available experimental data and a satisfactory agreement is found. The model is then implemented to calculate the local fuel/air equivalence ratio in internal combustion engines and determine the regions in the spray where the fuel/air mixture is ignitable, as well as zones of particulates and nitrogen oxides formation.