Prediction of Laminar-to-Turbulent Transition for the XV-15 Hovering Rotor Flows Using a Crossflow Model

The Amplification Factor Transport and Medida-Baeder’s local correlation-based transition models are extended to support crossflow-induced transition in NASA’s OVERFLOW CFD code. The algebraic crossflow correlations use helicity as an indicator of local crossflow intensity within the boundary layer. The implementation of these models is validated against standard test cases of crossflow-dominated transition: NLF(2)-0415 45° swept airfoil and TU Braunschweig sickle wing. The full-scale XV-15 rotor is simulated in low- and high-thrust conditions to evaluate the impact of crossflow transition in the prediction of rotor performance. A comparison is established between the fully-turbulent, baseline transition, and crossflow-extended transition models. Even though the transition models agreed more closely with experimental measurements than the fully-turbulent models, the addition of crossflow-induced transition resulted in minimal differences.