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In current study, for a special fabric that is used for parachute canopies; the permeability of the canopy has been estimated empirically and numerically. Moreover, the coefficients of Darcy's equation resulted from experiment, used in 2D numerical simulation of a single parachute-like body. Assuming permeability for the fabric, the drag coefficient was showed a 39 percent decrease rather than solid canopy. Comparison between solid canopy and permeable one, showed significant differences in the results, especially in streamlines and pressure distribution. In order to diminish the numerical effort, the canopies were taken as 2D hemi-spherical porous cups. So-called two dimensional numerical simulations using FLUENT® software was conducted on a group of paired permeable with two different diameters in various vertical and horizontal distances. The diameter of lower canopy was considered as half of the upper one. Tandem canopies use in order to reduce the inflation shock of main parachute. The lateral relative displacement of lower canopy to upper one has been considered in order to stimulate true descending conditions. The results showed the interaction between flow fields of canopies has strong effect on drag coefficient of the cluster parachutes. Therefore, determining the length of the risers as the vertical distance and relative diameter of parachutes and their interactions found to have tremendous effect in designing cluster parachutes. The study showed that the most desirable longitudinal distance between two canopies was equal to the diameter of lower canopy.

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In this paper conceptual design and optimization of gliding parachute configuration are discussed. To this end, a design cycle is planned for conceptual design procedure and an optimization-based design approach are established to provide an integrated design algorithm for gliding parachute platforms. The optimization problem is formulated with a cost minimization approach which is constrained by static stability and safe landing velocity as design criteria. The parachute configuration is defined with minimum required parameters and aerodynamics, stability and performance characteristics are provided based on a semi-analytical approach. Hence, a computational software is incorporated with theoretical approximations to provide the required disciplinary data flow in the design cycle.The significant design parameters are verified by available wind tunnel test data.Optimization problem is solved using genetic algorithm method whereas constraints are handled by penalty function approach.Trim points are obtained like an all-at-once approach through a simultaneous analysis and design algorithm. Finally, as a case study,optimized configuration is achieved for a real gliding parachute. Results show a fair estimation of parachute characteristics along with the reduction in manufacturing cost for new configuration up to 25%.

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In this paper, the effect of new control tools on the behavior of the parachute and its performance is studied by applying a compulsive stimulus in flow field. Modeling simulation and analysis performed with Ansys Fluent. A general geometry is proposed and simulations are carried out to indicate the effect of those stimuli on the flow behavior, parachute performance and high pressure areas on parachute. For the simplicity, the assumptions of axisymmetric and rigid wall of the parachute are used. Due to the large range of motion of fins compared to adjacent cells and also the importance of quality of mesh in the vicinity of the solid boundary, spring-based smoothing method for local and area remeshing are employed. In this way, the mesh quality for presenting the boundary layer and vortex generated in the solid surface are enhanced. The results depicted that using spherical arch geometries versus circular sector or parabolic geometries lead to some advantages. Permittivity of disk at the end of the parachute, has been triggered to increase the general drag coefficient dramatically up to around two times larger. Despite the existence of stimulation on a large area, flow field experience a total pressure drop. On the other hand if the stimulus does not exist the area is much smaller.