Reignition phenomena occurring in a supersonic nozzle flow may present a crucial safety issue for rocket propulsion systems.\nThese phenomena concern mainly rocket engines which use H2 gas (GH2) in the film cooling device, particularly when the nozzle\noperates under over expanded flow conditions at sea level or at low altitudes. Consequently, the induced wall thermal loads can\nlead to the nozzle geometry alteration, which in turn, leads to the appearance of strong side loads that may be detrimental to the\nrocket engine structural integrity. It is therefore necessary to understand both aerodynamic and chemical mechanisms that are\nat the origin of these processes. This paper is a numerical contribution which reports results from CFD analysis carried out for\nsupersonic reactive flows in a planar nozzle cooled with GH2 film. Like the experimental observations, CFD simulations showed\ntheir ability to highlight these phenomena for the same nozzle flow conditions. Induced thermal load are also analyzed in terms\nof cooling efficiency and the results already give an idea on their magnitude. It was also shown that slightly increasing the film\ninjection pressure can avoid the reignition phenomena by moving the separation shock towards the nozzle exit section.
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