Reynolds Number Trends in Computational Solutions of Two-Dimensional Airfoils with Taguchi Techniques and Grid Resolution.
Abstract
A procedure is proposed which allows the extension of incompressible high Reynolds Number wind tunnel data to even higher incompressible flight Reynolds Numbers using a computational solution about the airfoil. The new procedure is predicated on the performance of different grid refinements and turbulence models versus functions of y+, the vertical scaling parameter. When the difference between the computational force coefficients and the wind tunnel force coefficients are plotted against the log10(y+) or log10(y+/(square root of Re)), the data for the higher wind tunnel Reynolds numbers (approx. 2x10(exp 6) - 1x10(exp 7)) falls on one line. This behavior is noted for different thicknesses of airfoils at different angles of attack from zero lift to C(1max), although the corrected y+ ordinate is required only with moderate to high angle of attack. The airfoil is tested in the wind tunnel with enough Reynolds numbers to establish a trend and the computational solution is carried out at the same Reynolds numbers and angles of attack. Corrected flight Reynolds number Cd and C1 values appear to asymptote correctly on a trend curve showing force coefficient with Reynolds number. A statistical measure, adapted from Taguchi Techniques of quality control provides a measure of comparing the importance of turbulence model, angle of attack, Reynolds number, and wall spacing to the analysis. It is used for the first time here to help evaluate the performance of a computational solver. Taguchi results show that wall spacing is often, but not always, the most important parameter, and that the importance of turbulence model and Reynolds number is very dependent on the airfoil and whether lift or drag is being examined. Excursions carried out include different grid stretching and a possible extension from 2 to 3 dimensional.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 18, 1997
- Accession Number
- ADA326844
Entities
People
- Stephen C. Pluntze
Organizations
- Air Force Institute of Technology