Final Report of HSFD Phase II Transport Flight Data Evaluation by CFD Simulations
- Paper number
IAC-05-D2.5.07
- Author
Dr. Yukimitsu Yamamoto, Japan Aerospace Exploration Agency (ISTA/JAXA), Japan
- Year
2005
- Abstract
The HSFD (High Speed Flight Demonstration) Phase II flight experiment was conducted to reduce uncertainties in the transonic aerodynamic characteristics predicted by the wind tunnel tests and CFD simulations. A test vehicle is lifted to high altitude by balloon system to allow it to accelerate to transonic speeds in free-fall. After release, the vehicle can fly at a constant Mach number while changing its angle of attack quasi-statically, and its trimmed aerodynamic characteristics were estimated from the obtained flight data. Phase II flight experiment was conducted in collaboration with Centre National d’ Etudes Spatiales (CNES) at the Swedish Space Corporation’s Esrange site in Sweden in July 2003. In the transonic speed range of the HSFD flight, one of the most important problems to be investigated is a base flow characteristics. Complicated base flow has a great influence on the aerodynamics and also produces uncertainties through its unsteady flow features. In this paper, base flow analysis is mainly concerned and grid dependency of the base flow structures are investigated in detail with the sting interference effects of the wind tunnel model. Then, CFD evaluation of HSFD Phase II Experiment has been made at M inf =0.8 flight conditions. In HSFD Phase II flight, the angle of attack changes from 12 to 4 deg during the constant Mach number flight at M inf =0.8. The flight time is about 15 seconds and elevons are deflected about 9 deg. to take trim stability during the flight. CFD computations are made for the typical 3 cases at angles of attack alpha=12°, 8° and 4° with the flight Reynolds number of about 1 x 10e7. Comparisons of lift drag and pitching moment coefficients with the flight data are made. Excellent agreements are obtained for these coefficients. For pressure distributions in the base region, i.e. on the base and the upper body flap surface, present computations can reproduce the flight data by increasing grid points in the base regions. The final task of CFD validations has been completed. Cooperative CFD computations with CNES, France are underway and finished by April 2005. These detailed results will be reported at the IAC conference site. These new final results are not presented at any meetings and our original work is first proposed at this conference.
- Abstract document