The eN Method for Transition Prediction. Historical Review of Work at TU Delft

A historical review of work at TU Delft on the e N method for transition prediction is presented. The method is shown to be applicable to boundary layers with pressure gradient, suction and separation. Some applications to airfoil design will be discussed. An explanation will be given of the reason for the success of this linear theory to “predict” the position of transition which itself is a highly non-linear phenomenon. It will also be explained why the velocity profile shape factor H is a suitable parameter to characterize stability diagrams for flows with and without suction. Finally a new database method will be presented that is based on the observation that many stability diagrams show a remarkable similarity when properly scaled and shifted. The discussion will be restricted to two-dimensional incompressible flow.