Rarefied Flow Velocimetry

High-speed flows, such as supersonic and hypersonic flows, are crucial for aerospace technologies and the validation of fluid dynamics codes. This work characterizes the velocities of flows generated by an expansion chamber using three techniques: one intrusive, the Rapid Ionization Detector, and two optical, schlieren and a modified schlieren method combined with molecular iodine absorption.The Rapid Ionization Detector made it possible to study flows at pressures of 10 -6 mbar and speeds of 21 to 726 m/s. Using the characteristics method, flows with minimum temperatures of 29 K and Mach numbers of up to 12 were obtained. Schlieren velocimetry made it possible to visualize flows in voids of up to 200 mbar, with speeds of 5.2 to 66.5 m/s, temperatures of 297.6 to 300 K and a maximum Mach number of 0.2.The modified Schlieren method made it possible to visualize flows at pressures of up to 15 mbar, an order of magnitude lower than the conventional method, with speeds of 92 to 190 m/s, temperatures of 280.1 to 295.3 K and a maximum Mach number of 0.6.