Abstract:
The present research provides a performance comparison between several low Reynolds number airfoil profiles for the Mars Helicopter. The low density of the Martian atmosphere and the relatively small Mars Helicopter rotor result in very low chord-based Reynolds number flows, Re𝒸 = O(10³ - 10⁴). At low Reynolds numbers, flat and cambered plates can out-perform conventional airfoils, making them of interest for the Mars Helicopter rotor. Performance models are generated for the Mars Helicopter rotor based on a free wake analysis, and the results are compared with Mars Helicopter isolated rotor performance from previous work. A Reynolds-Averaged Navier-Stokes based approach is used to generate the airfoil deck using OVERFLOW. The model is constructed using airfoil data tables (C81 files) that are used by the comprehensive rotor analysis code CAMRADII. Performance results for the Martian atmosphere show improved performance for the cambered plate rotor over conventional airfoils, in terms of thrust for equal power and Figure of Merit for equal blade loading. The cambered flat plate airfoil produces 7% larger maximum rotor thrust versus the Mars Helicopter airfoils, and 5% larger Figure of Merit over the design thrust coefficient range. Larger maximum thrust allows an increase of design blade loading for the same thrust range for control authority, whereas the larger Figure of Merit reduces power requirements.