Overview
To execute a wind tunnel test under conditions nearer to the actual, the Reynolds number must be also in consistent with actual conditions as well as the Mach number and pressure.
Because the difference of the Reynolds number results in the difference of turbulence transition point and separation point between the wind tunnel test and the actual.
For conventional wind tunnels, methods of upsizing the wind tunnels or increasing pressures have been employed to bring the Reynolds number nearer to the actual. However these methods require to remarkably increase construction costs associated with the facility upsizing. Therefore, a method of increasing the Reynolds number of airflow within measurement cone by injection of LN² etc. for cooling the airflow has been recently used.
This method is shown below. As shown, LN² injected at an upstream portion of a wind tunnel cools the tunnel. In addition, the tunnel is provided with an exhaust system for vaporized GN².
Features
- This facility is available for a test under nearer conditions to the actual as the Reynolds number is increased.
- This facility is available for detail prediction about turbulence transition and separation points.
Planned Specifications:
 |
| Outline |
The following shows an outline and specifications of a cryogenic wind tunnel planned by us.
Main Specifications and Performance (planned values)
| |
Cryogenic Wind Tunnel |
| Type |
Continuous Circulation Type |
| Mach Number |
0.2 to 2.5 |
| Nozzle Outlet Diameter |
1.25m x 1.25m |
| Total Pressure |
110 to 500 kPa |
| Total Temperature |
90 to 300 K |
| Reynolds Number |
Up to 240 x 106 |
| Blowing Time |
Max. 30 minutes |
Overview
In addition to the increase of the Reynolds number in the tunnel, we predict low turbulent regions in supersonic nozzles by using CFD to research and develop supersonic nozzles (quiet nozzles), which enable tests in the low turbulent regions in the supersonic nozzles under nearer conditions to the actual. The following shows a concept of the low turbulent regions.
Furthermore, we are proceeding to research and develop a quiet nozzle which has broader low turbulent regions and a quiet wind tunnel provided with the nozzle.
Features:
- This facility is available for generation of low turbulent airflows nearer to the actual.
- This is available for detail prediction about turbulence transition and separation points on a specimen.
