Dynamic stability of the HUYGENS probe at Mach 2.5

Atmospheric re-entry is a critical phase for space vehicles. Dynamic stability issues play a crucial role for the success of their mission. In the context of the HUYGENS probe entry into Titanʹs atmosphere, dynamic wind tunnel tests were achieved to address its behaviour. The probe is placed at an initial angle of attack of 4° in the wind tunnel and its spontaneous movement towards a possible equilibrium angle is measured. The unsteady flow simulations presented below intend to obtain a reliable prediction of dynamic stability for future re-entry vehicles. The FLUSEPA code was used to perform these numerical simulations. st, an inviscid flow simulation has been performed at a Mach number of M = 2.5 , where the amplitude of the oscillations decreases although the probe should be dynamically stable. The frequency of the experimentally obtained oscillations is well predicted, however no damping has been found. So, the simulation was improved by the modelling of the turbulent effects. It enabled a proper prediction of the damping. Finally, the influence of the wind tunnel sting on the probe stability was numerically investigated. results emphasize the importance of viscosity and turbulence effects for the prediction of dynamic stability or more generally for wake flows.