Abstract: Development of the automatic transition prediction method for complex wing-body configurations is of great importance for the design of the Natural Laminar Flow (NLF) wing of high-subsonic civil transport aircraft. An automatic transition prediction method for wing-body configurations is developed using the structured multi-block grid three-dimensional Reynolds-Averaged Navier-Stokes (RANS) solver coupled with the fully dual e^N method based on the Linear Stability Theory (LST). The method proposed can predict the transition induced by Tollmien-Schlichting instability and cross-flow instability simultaneously. Transition prediction of the flow around the DLR-F4 wing-body configuration is carried out, and a comparison of the transition locations given by the numerical method and by the experiment validates the accuracy of the proposed method. The flow around the wing-body configuration of short and medium range civil transport aircraft using the NLF wing is simulated, and the simulation results are compared with the transition locations of the individual wing. The comparison result shows that the cross-flow instability of the NLF aft-swept wing boundary layer is increased due to the three-dimensional displacement of the fuselage, leading to early transition onset in the leading edge region of the wing root.

Key words: natural laminar drag reduction, dual e^N method, transition prediction, linear stability analysis, cross-flow transition