Abstract: The Alcantara Launch Center (CLA) is the Brazilian access to space and some international companies/countries intend to use it in the near future. It is positioned in a complex terrain and has some important buildings for space operations like the mobile integration tower (TMI) and the exit safety tower that affect the atmospheric turbulence locally. The main aim of this work was to study the atmospheric flow and dispersion of a poisoned gas (HCl) in the CLA by numerical simulations, including the topography of the cliff and the predominant meteorological conditions. The predominant wind directions considered were 70o, 45o and 90o. The cliff height was assumed to be 40 m. The simulations were performed by ANSYS Fluent 19.0 using the RANS realizable κ-ε turbulence model. The cliff was the major responsible for changing the flow. The regions with greater turbulence along the domain were accentuated or attenuated according to the wind direction. For 70o and 45o wind directions, the rocket launch site was mainly affected by the turbulent wake behind the exit tower. For the case of 90o wind direction, the wake generated by the TMI interfered the most at the launch site. Considering the HCl (as a scalar) dispersion case study for a hypothetical aborted launch the results showed harmful concentrations for short exposure, especially near the source at TMI. The HCl plume took about 10 minutes (520 seconds) to leave the domain and return the operations at safety mode.

Keywords: computational fluid dynamics (CFD) · short range forecast · rocket launch · toxic gases.