Experimental Study of Parachute Manners in Various Low Reynolds Numbers

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.