The invention provides a test bench for characterizing a flow of a two-phase fluid, the test bench comprising a fluid tank, a first pump suitable for taking fluid from the tank and for feeding first and second lines connected in parallel, each line being provided in succession, from upstream to downstream in the flow direction of the fluid, with: injection means for injecting air into the fluid; measurement means suitable for providing information about the proportion of the vapor phase relative to the liquid phase of the fluid; and a second pump or a Venturi.