(Georgia Institute of Technology, 2009-05)
Cordell, Christopher E., Jr.
Supersonic retropropulsion provides an option that can potentially enhance drag characteristics of
high mass entry, descent, and landing systems. Preliminary flow field and vehicle aerodynamic
characteristics have been found in wind tunnel experiments; however, these only cover specific
vehicle configurations and freestream conditions. In order to generate useful aerodynamic data that
can be used in a trajectory simulation, a quicker method of determining vehicle aerodynamics is
required to model supersonic retropropulsion effects. Using computational fluid dynamics, flow
solutions can be determined which yield the desired aerodynamic information. The flow field
generated in a supersonic retropropulsion scenario is complex, which increases the difficulty of
generating an accurate computational solution. By validating the computational solutions against
available wind tunnel data, the confidence in accurately capturing the flow field is increased, and
methods to reduce the time required to generate a solution can be determined. Fun3D, a
computational fluid dynamics code developed at NASA Langley Research Center, is capable of
modeling the flow field structure and vehicle aerodynamics seen in previous wind tunnel
experiments. Axial locations of the jet terminal shock, stagnation point, and bow shock show the
same trends which were found in the wind tunnel, and the surface pressure distribution and drag
coefficient are also consistent with available data. The flow solution is dependent on the
computational grid used, where a grid which is too coarse does not resolve all of the flow features
correctly. Refining the grid will increase the fidelity of the solution; however, the calculations will
take longer if there are more cells in the computational grid.