Research in Engineering and Aviation
Forebody Wake Effects on the Aerodynamics of an Annular Parachute
Author(s): McQuilling, M., and Potvin, J.
AIAA-2012-3332, presented at the 30th AIAA Applied Aerodynamics Conference, New Orleans, LA, June 25-28, 2012.
Annular parachute designs potentially offer the highest drag for hemispherical, non gliding parachute geometries. A concentric double annulus design was recently studied by the US Army to determine its performance and sensitivity to operating conditions. This paper presents time-resolved and time-averaged results from simulations using a Reynolds-Averaged Navier-Stokes flow solver to study the effects of a forebody wake on the aerodynamics of the double annulus at Reynolds numbers of 8.03x10^6 and 10.04x10^6. The parachute system consists of a large diameter annulus concentric with and offset below a smaller diameter annulus, and a payload represented by a flat disk. Previous simulations on the annular geometry (McQuilling and Potvin, Journal of Aircraft, 49(2), 566-575, March-April 2012) highlighted the transient nature of the flow around the annuli without a forebody payload, and this study was presented as paper AIAA-2012-3332 at the 42nd AIAA Fluid Dynamics Conference and Exhibit in New Orleans, LA, on June 25-28, 2012. Results indicate a severe reduction in parachute drag at both speeds when a 4ft diameter disk is placed 25 feet upstream of the current annular parachute geometry. This reduction was found to be caused by a wake vortex from the upstream disk that diverts the oncoming air away from the canopy mouth and instead into the canopy sides.