It's lame IMO, and does a diservice to supersonic aerodynamics by teaching the students that, 'hey, there is no market for this stuff, this is just to infrom you' I think we need something that lasts longer than a minute, for one, that can allow for force-moment measurement of models.
I am reading from my text; "Mechanics of Thhermodynamics and Propulsion", 2nd ed, by Hill & Peterson 1992; chapter 9 talks about centrifugal (not centripital) compressors. On page 426, it says, and I quote without permission:
In recent years designers have made great progess in raising the stage pressure ratio and in improving the efficiency of centrifugal compressors. Single-stage centrifugal compressors have been built with pressure ratios of 5:1 (and adiabatic efficiencies of 85%) and even 10:1 (with adiabatic efficiencies exceeding 80%).
These achievements have required major advances in both aerodynamic and mechanical design. Rotor tip speeds are now as high as 650 m/s, so that the velocity at te rotor exist is definitely supersonic; means have had to be found for decelerating this supersonic flow without excessive shock-induced or other losses.
This got me thinking. With proper design of the compressor and the motor to run it, could we create a supersonic wind tunnel that may last longer than a few minutes? Pressures may be high, but we could alter the temperature throughout the compression process so we don't alter the speeds. 650 m/s is almost Mach 2 at sealevel.