|M.Sc Student||Sobe Zeev|
|Subject||Elongational Behavior of Gel Fuels and Their Simulants|
|Department||Department of Mechanical Engineering||Supervisor||Mr. Alexander Yarin|
This research examines the performance of gelled fuels and their simulants in simple shear and elongation. The knowledge of the rheological behavior of these fluids under shear and especially under elongation is necessary for understanding spraying and breakdown processes of these fluids. A rheological analysis of the fluids was carried out, providing an answer to the question whether their rheological behavior can be characterized by a power-law tensorial equation. Simple shear, uniaxial elongation and surface tension experiments were carried out. The simple shear experimental results were in good agreement with the one-dimensional model of the power-law equation.
From the results of the uniaxial elongation experiments it was found that use of the power law for elongation does describe the experimental results and the rheological parameters K (consistency index) and n (power) found in simple shear and elongation are sufficiently close. Therefore, it was proved that the tensorial power law fits the rheological behavior of these fluids.
The elongational viscosity and the Trouton ratio were established for different gels. For these gels, the Trouton ratio was found to be of the order of 3, which corresponds to the ideal power-law behavior.
The results indicate that the three-dimensional power-law model is suitable for certain gels in simple shear and uniaxial elongational flows, and it can be thought for both practical and computational applications that these gels are “materials of power-law behavior”. In addition, it may be concluded that finding an ideal simulant for a fuel which rheologically matches it in both simple shear and uniaxial elongation, is a difficult engineering task.