The flow characteristics in the base region of a reentry vehicle are
very complex even though the geometry is quite
simple [1,2]. The external flow over the reentry body
is hypersonic while the flow in the base region is mixed
supersonic/subsonic flow. It is characterized by shock wave/boundary
(and shear) layer interactions at the lip of the base region.
Furthermore, the flow is turbulent in the base/separated region and
highly transient in nature. It is very challenging to accurately
predict such a flowfield.
A more robust Shear Stress Transport (SST) model is implemented. It makes use of the $k-\omega$ formulation
at low Reynolds number, without the need for damping functions, and
utilisers $k-\epsilon$ approach in free flows, avoiding the
sensitivity of the $k-\omega$ models in the free-stream turbulent
conditions. Compressibility corrections have been further
incorporated in the SST model to prevents the over prediction of the
mixing for high speed turbulent shear layers.
The configuration and dimension of a prototype reentry
vehicle [3], was chosen in this study. The flight physical properties: a 7-degree half-angle cone
with a 9.5-inch~(24.13cm) base diameter, a 1.06-inch~(2.6924~cm)
nose radius~(the bluntness ratio of 0.223) and a length of
31.04-inch~(78.8416~cm).
In this study, a freestream of 0.8572~$kg/m^3$ in density, 277.25~K
in temperature, quoted values at altitude of 10050~feet (3063.2~m)
and 10110~ft/s (3081.528~m/s) in velocity were selected. It gives a
Mach number of 9.2 inflow condition. The computational domain of
concern covers about three times of the cone length and base
diameter, as indicated in the contour plots below. The preliminary
result is shown in Figure 1, with a clear
interaction pattern among shocks, expansion waves, boundary/shear
layer and flow separation.
Figure 1 Contour plots of the simulated Mach number.
In the full paper, we will present a comprehensive investigation of
the hypersonic phenomena and insights into turbulent flowfield and
aerothermodynamic features of the reentry body. The turbulent
characteristics of the base flow and subsequent pressure and heat
profiles are investigated and explored in details.
1 J. P. Lamb and W. L. Oberkampf, Review and development of base
pressure and base heating correlations in supersoni flow. Journal of
Spacecraft and rocket. Vol32 No 1 1995.
2 M. MacLean, E. Mundy, T. Wadhams, M. Holden, M. Barnhardt and G.
Candler, Experimental and Numerical study of laminar and turbulent
base flow on a spherical capsule, AIAA paper 2009-0783.
3 J. K. Kryvoruka, Roll Torque evaluation (RTE) velicle postflight
test report, SAND 76-8001, 1976
