Subsonic, supersonic, transonic, and hypersonic wind tunnels:
If you’re looking to build an aircraft, you’ll need to know what kind of wind tunnel is right for your application.
Subsonic wind tunnels are designed to test models at speeds up to Mach 0.3 (approximately 230 mph). Subsonic tunnels can also be used for testing missiles and missiles systems.
Supersonic wind tunnels are designed to test models at speeds between Mach 1 (1,235 mph) and M∞ (the speed of sound). Supersonic tunnels are typically used for testing supersonic aircraft and rockets.
Transonic wind tunnels are designed to test models at speeds between Mach 0.5 (approximately 622 mph) and M∞. Transonic tunnels are typically used for testing cruise missiles and other high-speed aircraft.
Hypersonic wind tunnels are designed to test models at speeds above M∞. Hypersonic tunnels are typically used for testing hypersonic aircraft such as space shuttles or ballistic missiles.
Here’s a table to differentiate each type of wind tunnel further more:
|SUBSONIC WIND TUNNEL||TRANSONIC WIND TUNNEL||SUPERSONIC WIND TUNNEL||HYPERSONIC WIND TUNNEL|
|Increases the speed by||Increasing the blowing pressure||A downstream test section “extension” with adjustable pressure flaps works in unison with other wind tunnel components||Expanding the channel area downstream of the throat to accommodate the increased volume||Contracting the flow until it chokes in the throat of a nozzle. We then diffuse the flow which increases the speed supersonically.|
|Choking||Choking may be delayed by using a liner with slightly divergent walls.||The choke works in concert with the stagnation pressure control valve to achieve and maintain target airspeed.||Compressible flows experience mass flow choking||we contract the flow until it chokes in the throat of a nozzle.|
|Mach number Speed regime||M<0.8||0.8< M<1-1.2||1-1.2<M<5||M>5|
|Liners||Parallel-sided liners||Special liners are required||A Mach liner is fixed in the bottom of the test section||Liners with very narrow throats are required|
|Working fluid||Incompressible for low speed subsonic and compressible for high speed subsonic||Compressible||Compressible||Compressible|
|Shockwaves||effects of shock waves for this flow are commonly not considered||Sonic pockets are initiated as soon as the local Mach number reaches one and subsequently terminates in the downstream with a shockwave||Notable in this regime is the appearance of shock waves||Oblique shock shift closer to the object’s surface|