The present project aims at performing a numerical investigation of a capsule and supersonic parachute, modeled as a three-degree-of-freedom system, reentering the Martian atmosphere at supersonic regimes using the Large Eddy Simulation (LES) technique coupled with a wall-model to describe the near-wall dynamics. In recent years the interest towards the exploration of Mars has pushed a lot the research in the planetary atmospheric reentry, required by the necessity of predicting the dynamical loads applied to the capsule and its coupled motion with the supersonic parachute. However, the recent European missions aiming to place a lander on the Martian surface have been unsuccessful due to the lack of understanding of the oscillatory motions caused by the coupling between the capsule and the parachute, which creates a number of instabilities that were not predicted by theoretical models and experimental results. The use of modern HPC systems, boosted by the powerful GPU technology is essential to satisfy the high-resolution requirements of unsteady, high-fidelity simulations of the capsule-parachute system, which are of critical importance for the correct representation of the interaction between the wake and the canopy area. Accurate simulations of this flow configuration can drive the design of more reliable reentry systems and can serve as a reference database for the development of advanced models to reduce considerably the computational cost.
The present project is highly multidisciplinary, as it combines computational and theoretical facets of fluid dynamics, control theory of dynamical systems, applied mathematics and advanced scientific computing. If the objectives here proposed are fulfilled, the project will bring significant advances in a crucial aerospace research area and will have a strong impact from the technological point of view.
The ability to predict the dynamical behaviour of the payload motion in response to the parachute oscillations, caused by a strong nonlinear coupling between the system of bow shocks, turbulent wake and canopy, has demonstrated to be essential for the correct determination of loads and stresses applied to the capsule which affects its attitude and trajectory. An example of the importance of the research in this direction can be found in the ESA Exomars 2016 mission, which contained the Schiaparelli module to validate and demonstrate entry, descent and landing on Mars. According to the Schiaparelli Anomaly Inquiry report [7], a major event that contributed to the Inertial Measurement Unit (IMU) saturation that caused the loss of the lander was the high dynamic oscillatory motion which was caused by an incorrect prediction of the parachute deployment. The report clearly addresses how the prediction of this phenomenon is very complex and affected by several uncertainties such as winds, unsteady wake dynamics and canopy-area oscillations which were not expected in such intensity during the simulations. These flow features require a great accuracy in the computational domain and suitable numerical schemes that can preserve the integrity of the information even across large discontinuities (e.g. bow shocks). The proposed research aims at satisfying these requirements, with the objective of simulating a capsule and supersonic parachute coupled system with the LES technique coupled with a fluid-structure model suitable for time-accurate coupling with the Navier-Stokes equations.
The main scientific advancements that are expected from the usage of the requested resources are:
- Understanding of the important dynamical features of the wake interaction with the supersonic parachute
- Predict the fundamental instabilities that occur for a real parachute system such as divergence of inclination angle and flutter
- Investigate the dynamical behaviour of the system over a wide range of flight regimes and conditions
- Study the effect that the total capsule/parachute distance have in the stability of the system