Numerical Simulation of Supersonic Aerodynamic Interaction of a Parachute System

Abstract

In the present study the supersonic flow over rigid parachute models is studied by numerically solving the three-dimensional compressible Navier-Stokes equations at a free stream Mach number of 2. The parachute system employed here consists of a capsule and a canopy. Two models are considered: model A and model B. The former is the same model as the experiment, where the canopy is connected with the capsule by a rod, and the whole system is supported by another rod, while the latter does not have these rods. The objective of the present study is to examine the flow field produced by these models, and analyze the effects of aerodynamic interaction such as shock/shock and wake/shock interactions on it. The numerical results show good agreement with the experimental data in the case of model A. In addition, it is found that the difference of flow features between models A and B is rather small. The unsteady flow pulsation phenomenon observed in this study can be demonstrated using three processes; the bow shock formed ahead of the capsule periodically inflates and laterally expands, which is caused by upstream propagation and lateral expansion of the complicated wake/rear shock and fore shock/rear shock interaction systems.

Parametric Study on Aerodynamic Interaction of Supersonic Parachute System

“…3 show that a shock wave is formed ahead of the capsule, which inflates and moves outward in the radial direction, and this phenomenon is consistent with the pulsation flow mode reported in the literature [7,11,16,17], and is caused by the upstream propagation and lateral expansion of the complex capsule wake/canopy shock and capsule shock/canopy shock interaction systems [7]. However, a detailed observation of Fig.…”

“…5. Note that the results corresponding to d∕D 0.2 are reproduced directly from the previous studies [7,11]. Meanwhile, most of the results corresponding to d∕D 0.33 marked using hollow symbols are reproduced from the experimental study by our group [10].…”

“…Finally, the initial conditions were set equal to the freestream values, and nonslip, adiabatic boundary conditions were imposed on all the solid body surfaces. Notably, a turbulence model was not employed in the present simulations, because the laminar numerical simulations were performed on a rigid parachute model with a satisfactory agreement with the experimental data [7,11]. As a result, the present simulations simply used an extended form of the numerical code employed in [7,11].…”

“…Note that the grid was created by a meridional plane, due to the axisymmetric configuration of the parachute system. The 3-D view and the validity test of grid convergence were demonstrated in the previous studies [7,11], and hence the details are omitted here. In the present study, all of the simulations were performed using a similar grid density.…”

“…Recent studies using subscale Mars Science Laboratory parachute models have shown that the flow instability of the parachute system originates from the aerodynamic interference between the canopy shock and the capsule wake, and that it depends on the Mach number, the Reynolds number, the capsule shape, and proximity to a forebody [6]. Xue et al [7] simulated the performance of a rigid parachute system with a rather small trailing distance (X∕d 2.38) and found that the flow field around the parachute was characterized by an unsteady pulsation mode. It was also found that the sting between the canopy and capsule has a rather small effect on the flow field and pressure distribution on the body surfaces, and the pulsation mechanism for the case without a sting is identical to that for the case with a sting.…”