The Low Density Tunnel (LDT) is rarefied flow facility, with the ability to produce flows with high Knudsen numbers representative of those experienced in the slip regime. The facility is continuous and is capable of measuring aerodynamic coefficients by use of a magnetic suspension balance.


  • Knudsen numbers up to 0.3
  • Max p0 = 200 kPa
  • Max T0 = 600 K
  • Contoured Mach 6 nozzle, 30-60 mm core flow
  • Mach 5-10 conical nozzle with 20-50 mm core flow
  • Magnetic force balance
  • 2 axis wake traverse
  • 3 axis traverse for model re-orientation


  • Video cameras capable of imaging at over 1 million frames/s
  • Free flight data acquisition hardware
  • High powered lasers and associated diagnostics.
  • High speed light sources for visualisation
  • Emission spectroscopy equipment from the visual to mid-wave infrared
  • High bandwidth pressure transducers
  • High response heat flux gauges and signal conditioning