That seems like a pretty big test section. Cool.
A relevant quote for the Carben
"For example, the Reynolds number of 1/4-scale models tested at flight velocities at atmospheric pressure would be too low by a factor of 4. Because the Reynolds number is also proportional to air density, a solution to the problem could be to test 1/4-scale models at a pressure of 4 atmospheres. The Reynolds number would then be the same in the wind tunnel tests and actual full-scale flights."
Looks like the gubmint gots one that goes to 10 atm...
Low-Turbulence Pressure Tunnel
The Langley Low-Turbulence Pressure Tunnel (LTPT) is a single return, closed-circuit tunnel that can operate from 1 to 10 atmospheres. The LTPT has been used for tests of high-lift airfoils, basic research, and theory validation. LTPT's capabilities of low disturbance, variable density tests and high-lift, multielement airfoil tests at Mach numbers from 0.05 to 0.5 and Reynolds numbers from 0.4 x 106 to 15 x 106 per foot are unique in the world. This tunnel is ideal for preliminary aerodynamic configuration screening because of low operational cost and relatively inexpensive models.
NASA - Wind Tunnels at NASA Langley Research Center
Interesting stuff.