چكيده فارسي :
Study of parachutes is very important in aerospace
industry. In this research, the effect of various Reynolds
numbers on a parachute with a vent and without a vent
at the top on drag coefficient in a steady and turbulent
condition is studied. After a complete research on an
efficient grid study, the drag coefficients are calculated
numerically. The Reynolds number is varied from
39000 to 390000 (5 m/s to 50 m/s). It is found that, for a
parachute without a vent at the top, as the Reynolds
number is increased from 39000 to approximately
230000, the drag coefficient is decreased from about
2.15 to 1.6, and then as the Reynolds number is
increased to 390000, the drag coefficient stayed
constant. As the vent ratio of the parachute is increased
from zero to 5, the drag coefficient was increased and
for further increase of the vent ratio, the drag coefficient
decreased, but the general variation of drag coefficient
was the same as of same parachute with no vent.
