M.Sc Thesis

M.Sc StudentDesyatkov Anat
SubjectThe Effect of High Vapor Pressure Additives on the
Atomization and Combustion of Gel Fuels
DepartmentDepartment of Aerospace Engineering
Supervisor PROF. Benveniste Natan
Full Thesis textFull thesis text - English Version


The motivation for the present investigation was to increase the burning rates of gel fuel droplets by adding high vapor-pressure species (HVPS) and also adding highly energetic metal particles.

The addition of high vapor-pressure species into a gel fuel matrix can theoretically promote the combustion efficiency of the fuel because of their high volatility. In the present study, the characteristics of various gel fuels with high vapor-pressure species and metal particles were investigated on the basis of their rheological, spray and combustion properties. Experiments were conducted using gelled Jet-A1 that contained hexane and cyclohexane at various concentrations, aluminum, and magnesium. From the possible candidates that were initially examined, hexane and cyclohexane were found more suitable due to their high vapor pressure and lack of toxicity. The gel fuel compositions that were investigated were based on Jet-A1 gelled with 7.5 % Thixatrol and contained combinations of hexane (0%, 15%, 30%), cyclohexane (0%, 15%, 30%), aluminum (0%, 15%, 30%) and magnesium (0%, 30%).

The various compositions of gelled fuel that were produced were characterized rheologically using parallel-plate and cone-and-plate configurations. The atomization properties were investigated using a doublet impinging-jet configuration. Hexane has the higher vapor pressure between the two species; therefore, its influence is more significant in the combustion process and it was chosen to be atomized. For the combustion experiments, the combustion chamber pressure was 11 bar to simulate ramjet flight conditions at an altitude of 10K ft. Air entered the combustion chamber at two different temperatures, 300 K and 800 K. Combustion efficiency was calculated taking into consideration the heat loss to the chamber and the environment. 

The results were compared to experimental results from the literature and the comparison indicates that the addition of the volatile compounds has only a minor effect on the atomization and combustion.