Linear stability analysis of the flow around natural laminar flow airfoils

Linear stability computations over airfoils play an important role in the design of natural laminar flow airfoils - in reducing the risk of a massive separation by the elimination of excess acceleration upstream while maintaining laminar flow; and in the prediction of the onset of transition to turbulence. This report describes a linear stability code developed at CTFD, NAL for airfoil analysis. The code is validated against known results for NASA DESB159 airfoil. Disturbance amplification factors are computed for (i)a Wortmann FX-63-137 airfoil at an angle-of-attack alpha=o deg for Reynolds numbers of 80,000, 0.2 million and 2 million; (ii) a GAW-2 13% airfoil at alpha=0 deg and Reynolds number equal to 60 million. Finally, an en correlation for transition onset is discussed briefly