Blowdown wind tunnels are cost-effective tools to study convective heat transfer and aerodynamics in high speed flows. The wind tunnel must replicate the actual running operation around the prototype, but additionally the conditions should be easy to reproduce multiple times by independent researchers. Consequently, the spatial and time dependent uniformity of the flow conditions around the test article should be assessed carefully. This paper provides design rules and particular features of the components that ensure adequate flow conditioning for blowdown wind tunnels suitable for subsonic and supersonic operation with massflow limits ranging from 1kg/s to25 kg/s and Reynolds over meter all the way from 10~5 up to 4×10~7. In terms of Mach numbers the described flow conditioning system will be suitable from 0.01 up to a maximum of 7 if a convergent divergent nozzle is equipped prior to the test section. The performance was assessed using 2D and 3D Steady and Unsteady Reynolds Averaged Navier Stokes simulations. The quality of the flow conditioning was quantified in terms of total pressure loss and Root Mean Square-Deviation of the axial flow velocity inside of the test section.
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