Automatic Transition Prediction in a Hybrid Flow Solver, Part 1: Methodology and Sensitivities

Abstract

A hybrid Reynolds-averaged Navier�Stokes solver, a laminar boundary-layer code, and a fully automated local, linear stability code were coupled to predict the laminar�turbulent transition due to Tollmien�Schlichting and crossflow instabilities using the eN method based on the two-N-factor approach. The coupled system was designed to be applied to three-dimensional aircraft configurations which are of industrial relevance. The transition prediction methodology provides two different approaches which are available to be used in different flow situations. Both approaches are described and tested in detail. The application of the complete coupled system to a two-dimensional two-element airfoil configuration and a three-dimensional generic full aircraft configuration is described and documented in this paper. The prediction of the laminar�turbulent transition lines was done in a fully automatic manner. It will be shown that complex aircraft configurations can be handled without a priori knowledge of the transition characteristics of the specific flow problem. The computational results are partially compared to experimental data. This article is the first of two companion papers: the first dealing with the transition prediction methodology and the second dealing with the practical application of the coupled system.