DPW4 Results Using Different Grids Including Near-Field/Far-Field Drag Analysis

CFS Engineering and RUAG Aviation participated in the 4th Drag Prediction Workshop organized by AIAA in June 2009. Calculations were made for the Common Research Model (CRM) configuration using the Navier Stokes Multi Block solver NSMB on the grids generated at CFS Engineering. After the workshop the polars were computed on the medium multi block structured grids provided by other workshop participants for the CRM configuration with zero degree horizontal tail deflection. All these results were processed by a far field drag extraction tool developed jointly by RUAG Aviation and CFS Engineering. This paper first summarizes the theory behind the drag extraction tool. The results of the different calculations are presented and a detailed analysis of the drag breakdown on the different grids is given. This shows that the spread in drag coefficients obtained on different grids is much lower when using the effective drag computed by the drag extraction tool then when using the near field drag.