The University of Cincinnati (UC) erosion wind tunnel shown schematically in the left figure consists of the following components: particle feeder (A), main air supply pipe (B), combustor (C), particle pre-heater (D), particle injector (E), acceleration tunnel (F), test section (G), and exhaust tank (H). Abrasive particles of a given constituency and measured weight are placed into the particle feeder (A). The particles are fed into a secondary air source and blown into the particle preheater (D), and then to the injector (E), where they mix with the primary air supply (B), which is heated by the combustor (C). The particles are then accelerated via high velocity air in a constant-area steam-cooled duct (F) and impact the specimen in the test section (G). The particulate flow is then mixed with coolant and directed to the exhaust tank.
As can be seen from the schematic diagram, the tunnel geometry is uninterrupted from the acceleration tunnel throughout the test section in order to preserve the aerodynamics of the flow passing over the samples. Particles impacting the coupon and their impact velocity are calibrated with the tunnel airflow, while the particle impingement angle is controlled through the coupon orientation. The particles are fed into the flow after the test sample reaches equilibrium temperature.