X2 Super-Orbital Expansion Tube
This is the next generation super-orbital expansion tube after X1.
It is capable of operating at similar conditions to X1 but has a larger diameter (85 mm) facilitating larger models.
The driver section in X2 has a compound piston allowing for a shorter compression tube than would be otherwise necessary.
- A pilot expansion tube designed and constructed to test concepts for the larger X3 tube
- Features a compound-piston driver which consists of a light outer piston and a heavier inner piston. The latter separates from the outer piston after some initial compression and the inner piston continues down a smaller diameter compression tube to complete the driver compression process.
The conditions to be expected in the flow assuming equilibrium are given in the following table:
Parameter |
Moderate Enthalpy |
High Enthalpy (Nitrogen) |
||
Free-stream |
Normal Shock |
Freestream |
Normal Shock |
|
Pressure (kPa) |
67 |
1890 |
3.3 |
220 |
Temperature (K) |
4900 |
8500 |
4800 |
11500 |
Density (kg/m3) |
0.046 |
0.52 |
0.0022 |
0.030 |
Enthalpy (MJ/kg) |
27 |
27 |
61 |
61 |
Velocity (km/s) |
6.55 |
0.6 |
10.3 |
0.7 |
Mach Number |
4.8 |
0.3 |
7.3 |
0.2 |
Diss. fraction N2 |
- |
0.47 |
0.06 |
1.0 |
Ion. fraction N |
- |
- |
- |
0.06 |
X2 was used in 2011 to measure standoff distances at conditions that are representative of re-entry of objects into the earth's atmosphere. As a baseline test case for analytical and CFD modelling, a 60 mm diameter sphere was located in a 10.0 km/s flow and the resulting video is avilable to view here: