Numerical Simulation of Supersonic Flow Over OREX Reentry Capsule

The Orbital Re-Entry Flight Experiment (OREX) was the Japanise experiment implemented in 1994 to investigate flight conditions of capsules. A better performance of thermal protection systems and aerodynamic heating were the goals. Experiments were similar to those used by NASA.

A high-speed flow over reentry capsule generates a bow shock wave. This shock wave causes high pressure and temperature over the surface, generating damages for the reentry vehicle.

campomach_cfdos_2

Figure 1

In front of the body, (zone a) figure 1, the bow shock is detached and between them there is a supersonic zone flow and subsonic flow. Each zone is divided by the sonic line (zone b) whose position is of important interest for reserachers since it defines the magnitude of  global drag coefficient.

When the flow comes at the edge of the vehicle,  it turns and expands very fast (zone c), and the boundary layer detaches from the body. This phenomenon creates a free shear layer between two different velocities (zone e) thus the free shear layer divides the recirculating region behind reentry capsule (zone d) and the free stream. Eventually, the flow is recompressed downstream by the tail shock (zone f), which is formed because the flow becomes supersonic when it passes through the expansion fan on the corner.

The Numerical simulation was carried out using sixth order schemes to solve derivatives of Navier-Stokes equations. Mach number is 1.5 and the fluid is air. Boundary condions were implemented according to [1]. LES technique was used to solve turbulent structures.

Thanks to PhD. Martin Salinas of the Engineering Intitute of UNAM.

References

[1] Poinsot and Lele “Boundary Conditions for Direct Simulations of Compressible Viscous Flow “. Stanford 1991

More info related with OREX http://www.rocket.jaxa.jp/fstrc/0c01.html

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