Andre-Jacques Garnerin was a fearless Frenchman who catapulted out of a hot air balloon and into the history books in 1797 after he bumped and swayed his way to the ground supported by a homemade parachute. Since Garnerin took his leap into the record books 201 years ago, parachutes have been used extensively to drop people and cargo from aircraft for sport and to save lives. Hamid Johari of Worcester, Mass. , an associate professor of mechanical engineering at WPI, recently began looking at parachutes in a new way to explore the aerodynamics of canopy inflation. Using the same material the Army uses, the researchers are building parachutes that are reduced in scale by a factor of 30 to 60 times.
Nothing is stitched.
Each model will be evaluated in an experimental rig in the water tunnel in Higgins Laboratories, where the flow field can be measured. The flow field is the 'map' of the fluid velocities in the vicinity of each parachute. They exert the forces that slow jumpers down. Doing our experiments in the water tunnel, with velocities slower than in the atmosphere where parachutes open in real-world situations, gives us more time to acquire data. That data will provide a better understanding of the flow field-and that, in turn, will lead to a more systematic approach to designing parachutes, specifically as it relates to their opening time and opening shock.