Master thesis and internship[BR]- Master's thesis : Validation of the Simerics Valve Template for Dynamic Fluid-Structure Simulations and Application to the Purger-Check Valve of the Ariane 6 Kick-Stage[BR]- Integration internship

Abstract

This thesis investigates the dynamic fluid-structure interaction of valves using the dedicated Valve Template module in the commercial computational fluid dynamics software Simerics. The study was conducted during an internship at Safran Aero Boosters and represents the first implementation of this tool within the company's workflow. A Purger-Check Valve, one of the main components of the propulsion systems for ArianeGroup's Ariane 6 rocket, was selected as a case study to validate the template.

A comprehensive numerical strategy was developed, beginning with the translation of experimental data on cracking and reseat pressures into simulation parameters, such as dynamic boundary conditions. Methodologies for mesh and time step convergence studies specifically tailored to dynamic simulations were proposed. In particular, a novel strategy was introduced to identify a critical operating case, which then guided the mesh refinement while balancing accuracy with computational cost. A two-step procedure was established for time step convergence, combining full-cycle and fixed-boundary simulations. A computational cost study also identified optimal parallelization strategies and highlighted the benefits of variable time stepping.

The simulations successfully reproduced the dynamic opening and closing of the Purger-Check Valve, showing coherent results compared to experimental data. Unlike experimental cracking and reseat pressures, which diverged after repeated activations, the computational fluid dynamics predictions remained consistent, underscoring the reliability of the methodology. Additional findings include the identification of numerical oscillations linked to the stability of the proprietary dynamic scheme and the construction of a user-defined stability criterion to guide the choice of time steps.

Overall, this work demonstrates the feasibility and robustness of using the Simerics Valve Template for dynamic valve simulations in an industrial context. It provides a reusable framework for future studies at Safran Aero Boosters, with potential extensions to other valve geometries, alternative computational fluid dynamics tools, and further improvements in numerical stability and efficiency.