الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 162 |  |  |
| | | from | 162 | | |
Abstract
In this study, a diffusion jet flame consisting of a newly developed flame
holder with three coaxial pipes to convey air and fuel to the combustion zone,
is investigated experimentally to simulate the ramjet effect. The flame holder is
a double cone with three fuel exit ports on the top cone to improve the mixing
of fuel and air. The inner pipe, which is connected to the flame holder, conveys
the fuel to the injection ports. The middle pipe conveys the primary air while
the outer pipe conveys the secondary air to the combustion zone to remove the
still air from around the flame as in ramjet applications.
Two approaches were investigated in the current study. In the first
approach, the experiment was carried out by placing the outlets of the flame
holder, the primary air pipe, and the secondary air pipe at the same level. The
velocity of air flow to the combustion zone was changed many times in order
to study its effect on the flame. The results showed that the change in air velocity
flowing to the combustion zone has an impact on flame temperatures, flame
stability, flame length, and flame width.
In the second approach, the flame holder and the primary air exits were
located at a fixed position (called datum line at Z4=0) while the secondary air
exit position was changed many times below and above this datum line. The
results showed that the secondary air exit location had an effect on the flame
temperature distribution, flame stability, flame shape, flame length, and flame
width. The optimum position of the secondary air pipe was found to be above
the datum line at Z5 = 7.5 mm, where the flame temperature and length are
considered relatively high compared to other positions.Both approaches discussed creating a kind of air shield around the
combustion area to concentrate the airflow over the combustion zone. This air
shield has the potential to affect the recirculation zone above the flame holder
by reducing the amount of primary air dispersion to the surroundings,
consequently affecting flame temperature, air-fuel mixing, and flame length.