Uncertainty Quantification and Sensitivity Analysis applied to an under-expanded single jet

The aim of CFD simulations is to model and compute the ideal performance of a flow under some particular conditions. A classic approach is to perform simulations with fixed parameters and boundary conditions. However, this is not accurate enough due to the fact that under realistic conditions, some parameters may be uncertain. In recent years, the interest of undertaking the simulations under uncertainty is increasing, but is not yet a common rule and ’incomplete’ simulations are still taking place. This procedure could be missing information such as whether mechanical tolerances are influential in dramatic parts of the flow or the relevancy in accurate tunning of turbulence models. Taking this knowledge into consideration, Non-Intrusive Uncertainty Quantification (UQ) has been applied to 3D RANS simulations of an under-expanded jet, in order to understand the impact of input uncertainties. Results show that some regions of the jet plume are very sensitive to a combination of both physical and turbulence model variance. These regions are in fact corresponding to the parts of the jet where screech and shock-cell noise is generated, so this can be an indicator of a relevant impact of uncertainties in jet noise emmission, what can guide to future research and more robust developments in aircraft industry