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Description
This contribution focuses on the numerical analysis of large meteoroids during their entry into Earth atmosphere. After a survey of the available flight data, two entries of meteoroids have been reconstructed: the Chelyabinsk event that occurred in 2013, and a meteor, which felt in the Atlantic Ocean in February 2016, the Saint-Valentine day. For both meteoroids, the most likely trajectories have been computed with a three-degree-of-freedom trajectory tool. Computations have been then performed using a non-equilibrium Navier-Stokes solver at specific points of the trajectories to determine the temperatures and the composition of the mixture around the meteoroids, as well as the surface heat-flux. The flow-field distributions of Mach number predicted at 31 km of altitude for the St Valentine meteoroid is shown in Figure 1 (Left), while the corresponding VUV spectrum is shown in the right part.
Fig. 1: Left: Mach number distribution at 31 km of altitude for the St Valentine meteoroid; Right: Corresponding VUV spectrum
Then, the SPARK line-by-line radiation code has been selected to post-process the CFD results for predicting the radiative heating. It has to be noted that SPARK capabilities have been extended via an updated database capable of reproducing VUV molecular radiation. The spectra obtained for the St Valentine meteoroid at 80 and 31 km of altitude, highlight the strong contribution of molecular VUV radiation at high altitude as shown in Table 1. Then, comparisons have been carried out between the radiative heating calculated using engineering correlations and the CFD/radiation computations at the different altitudes. The comparison put in evidence the lack of reliability of usual stagnation point correlations particularly at low altitude and high level of stagnation pressure.
Table 1: Part of VUV contribution as function as altitude for St Valentine meteoroid
Finally, the last part of this work focuses on the meteoroid demise. Firstly, a qualitative analysis of the thermal response of the meteoroid accounting for the available element on material opacity for the incoming radiation wavelength range has been conducted, in a second step the radiative and convective blockages have been estimated. The final point is to propose a scenario corresponding to the meteoroid demise and supported by the outcome of this work.
Summary
This contribution focuses on the numerical analysis of large meteoroids during their entry into Earth atmosphere.
