Low Reynolds Number Airfoil Evaluation for the Mars Helicopter Rotor

Koning, Witold J K ; Romander, Ethan A ; Johnson, Wayne

关键词: AERODYNAMIC DRAG;    ANGLE OF ATTACK;    COMPUTATIONAL FLUID DYNAMICS;    FIGURE OF MERIT;    HELICOPTERS;    LOW REYNOLDS NUMBER;    PERFORMANCE PREDICTION;    ROTORS;    THRUST;    AIRFOIL PROFILES;    BOUNDARY LAYERS;    FLIGHT OPERATIONS;    MARS ATMOSPHERE;    NAVIER-STOKES EQUATION;    ROTARY WINGS;    THRUST CONTROL;   

RP-ID  :  ARC-E-DAA-TN53889

学科分类：航空航天科学

美国|英语

来源: NASA Technical Reports Server

【 摘 要 】

The present research is aimed at providing a performance model for the Mars Helicopter (MH), to understand the complexity of the flow, and future regions of improvement. The Martian atmosphere's low density and the MH's relatively small rotor result in very low chord-based Reynolds number flows, Rec = O(10(exp 3)-10(exp 4)). The low density and subcritical Reynolds number reduce the lifting force and lifting efficiency, respectively. The high drag coefficients in subcritical flow, especially for thicker sections, are attributed to laminar separation from the rear of the airfoil. The goal is to generate a performance model for the MH rotor for a free wake analysis, since the computational budget for a complete Navier-Stokes solution for a rotating body-fitted rotor is substantial. In this study, a RANS-based approach is used to generate the airfoil deck using OVERFLOW with stitched experimental data for very high angles of attack. The model is presented through airfoil data tables (C81 files) that are used by comprehensive rotor analysis codes such as CAMRADII, or the mid-fidelity CFD solver RotCFD. These codes have proven to provide accurate performance predictions for all rotor operations at only a fraction of the computational expense of three- dimensional body-fitted viscous grids.