Approximated Steady Aerodynamic Characteristics for two Cuboids and a Hemispherical Shell used in Airdrop Simulation

Abstract

The paper presents the approach and the results from the CFD analysis and the further evaluation of the aerodynamics characteristics of three different bluff body shapes used in an airdrop and parachute simulation. In a joint effort between the Institute of Aerodynamics and Flow Technology and the Institute of Flight Systems within the internal DLR-project MiTraPor II, aerodynamic coefficients for two cuboids and a hemispherical shell representing scaled models of payloads and parachute were evaluated. The evaluation of the aerodynamic coefficients is based on a CFD analysis of a first cuboid with an aspect ratio of 11 x 9 x 5, a second cuboid (or semi-cube) with 11 x 9 x 9 and a hemispherical shell. The analysis covers the full 360° angle of attack range with a sideslip angle of zero, and additional points at β ≠ 0. For being used within the airdrop and parachute simulation, the CFD results were post-processed to obtain analytical approximations for the steady aerodynamic coefficients.

Development and Validation of a RANS-based Airdrop Simulation Approach

“…11 A multi-fidelity simulation approach was established, which on the one hand allows for the real-time computation of entire trajectories based on aerodynamic lookup tables, including the influence of different types and numbers of attached parachute systems. 12,13 The strong interference effects between the wake of the aircraft and the initial motion of the dropped supply, however, cannot be examined with this approach. Hence, a high-fidelity simulation approach 14 called AIRBORNE (Airdrop simulation based on Reynolds-averaged Navier-Stokes equations) was developed simultaneously.…”

Validation of the Flow Topology Around Several Airdrop Cargo Configurations at Static Conditions

“…In recent years, the progress in numerical tools allowed for a more accurate simulation of the flow field behind the aircraft 4,5 or about cargo configurations 6,7 . Increasing efforts have been taken to apply highfidelity CFD methods to simulate near-field airdrop trajectories [8][9][10] .…”