چكيده فارسي :
Abstract
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 by free flow analyses is
studied. The flexible canopies, with 15cm diameter, are
experimented on a vehicle in different speeds and the
Reynolds number is varied from 87320 to 349200 (8.33
m/s to 33.3 m/s). It is found that, for a parachute without
a vent at the top, as the Reynolds number increases, the
drag coefficient is decreased from about 1.75 to 1.35.
For the Reynolds number between 87320 to 291000 as
the vent ratio of the parachute is increased from zero to
5 percent of the parachute inlet diameter, the drag
coefficient was increased and for further increasing of
the vent ratio diameter, the drag coefficient decreased, it
is notable that in higher Reynolds numbers, by
increasing the vent diameter from 0% to 20%, the drag
coefficient was decreased.
