AEROSCIENCES EVALUATION AND TEST
CAPABILITIES PORTFOLIO
IS INVESTING IN
A CAPABILITY CHALLENGE
DESIGNED TO ASSESS THE ABILITY
OF COMPUTATIONAL FLUID DYNAMICS
TO ADDRESS AEROSCIENCE
PREDICTION REQUIREMENTS
AT HIGH SUPERSONIC SPEEDS.
TO DO THIS, A SERIES OF
WIND TUNNEL TESTS
AND IDENTICAL CFD ANALYSIS
WILL BE CONDUCTED AND COMPARED
TO DETERMINE THE ACCURACY
OF CFD RELATIVE TO
WIND TUNNEL TESTING.
THE INFORMATION GAINED
FROM THIS CHALLENGE CAN BE USED
TO OPTIMIZE FUTURE TESTING
AND LEAD TO A MORE EFFICIENT
UTILIZATION OF OUR CAPABILITIES.
ONE COMPARISON WAS
THE CONTROL SURFACE
EFFECTIVENESS
FOR A HYPERSONIC ENTRY
DESCENT VEHICLE
FOR LANDING HUMANS ON MARS.
THE MIDLIFT TO DRAG RATIO,
CobraMRV.
THIS VEHICLE HAS TWO BODY FLAPS
FOR AERODYNAMIC CONTROL
DURING DESCENT THROUGH
THE MARTIAN ATMOSPHERE.
THESE FLAPS ALLOW THE VEHICLE
TO ADJUST ITS FLIGHT PATH
VERY PRECISELY
BEFORE RETROROCKETS TAKE OVER
TO FURTHER SLOW AND MANEUVER
THE VEHICLE FROM MACH 2
DOWN TO A SOFT LANDING.
WE ARE PARTICULARLY INTERESTED
IN HOW WELL CFD PREDICTS
THE MEASURED FORCES AND MOMENTS
GENERATED BY DIFFERENT
FLAP DEFLECTIONS,
INCLUDING HINGE MOMENTS.
AND FOR THIS COMPARISON,
CFD PRODUCED GOOD,
QUALITATIVE PREDICTIONS.
OF COURSE, THE UNCERTAINTIES
IN BOTH THE EXPERIMENTAL DATA
AND THE CFD RESULTS
NEED TO BE EVALUATED
BEFORE WE CAN DRAW
FIRM CONCLUSIONS ABOUT
THE ACCURACY OF THE SIMULATIONS.
THE CFD PREDICTIONS HAVE
SO FAR BEEN VERY CLOSE
TO THE WIND TUNNEL DATA
AND HAVE HELPED TO UNDERSTAND
THE AERODYNAMIC BEHAVIOR
WE MEASURED IN BETTER DETAIL,
EVEN TRACKING DOWN
SOME INCONSISTENCIES
IN THE EXPERIMENTAL DATA.
WHAT IS STRIKING IS THE FACT
THAT THE EXPERIMENTS IN CFD
HAVE DEFINITE STRENGTHS
AND WEAKNESSES,
AND COMBINING THEM LETS US
UNDERSTAND MORE ABOUT
THE COMPLEX FLOWS THAT CAN
HAPPEN IN THE WIND TUNNEL
AND AROUND THE RELATIVELY
SIMPLE VEHICLE SHAPE
WE'VE STUDIED SO FAR.
WE'RE LOOKING FORWARD
TO STUDYING SEVERAL
MORE COMPLICATED FLOWS
IN THE NEAR FUTURE.