טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentRozenberg Sagi
SubjectInvestigation of Fuel Atomization in Liquid Fuel Combustor
DepartmentDepartment of Aerospace Engineering
Supervisor Professor Emeritus Yeshayahou Levy


Abstract

This work presents a performance analysis of a liquid fueled, coaxial, confined combustor equipped with an air-assist atomizer and vaporizer.  The work covers a description of the experimental study with CFD calculations performed elsewhere.  The motivation was calibration of a CFD model for a specific combustor geometry. This rigorous task involved velocity measurements in a confined flame stabilized by a conical bluff body.

Measurements were performed in the recirculation zone established downstream of the bluff body. In such a combustor the fuel is partially or totally gasified in the vaporizer. Fuel is injected from an air-assisted atomizer, where partially aerated liquid fuel discharges rapidly from the orifice and breaks up into ligaments, hitting the hot mushroom shaped cover. This scheme enables stable combustion process at low fuel to air ratios. This is due to the good fuel vaporization and effective fuel air mixing before the mixture enters the reaction zone.

The fuel used in the experimental study was n-heptane (C7H16). Fuel injection was realized by pressurized nitrogen gas from a standard vessel. The primary air was preheated before being introduced into the combustor in order to achieve stable combustion, especially for lean fuel mixtures.

Velocity profiles in the combustion chamber were measured by the LDV technique. Flow visualization was provided with the aid of Al2O3 seeding particles. A small and controlled amount of a dry shop air was used as the seed carrier. 

Simulation results of the CFD model display a close agreement with the experimental findings near the recirculation zone, both for non-reacting and reacting flow.