Evaluation of Transitional Effects in Rotorcraft Applications

Transition in computational simulations is still an emerging area of algorithm development for rotorcraft applications. It, along with turbulence modeling, is assumed to be the source of errors in many numerical analyses. To explore the influence of transition, two transition methods are analyzed across different configurations of interest to rotorcraft. The Langtry cross flow model for Reynolds-Averaged Navier-Stokes (RANS) solvers and a consistent transition approach to the Georgia Tech hybrid Reynolds-Averaged Navier-Stokes and Large Eddy Simulation (RANS-LES or HRLES) are evaluated. The configurations include a prolate spheroid, a rotor-body interaction (ROBIN) generic model fuselage, and a two-dimensional yawed wing. The solutions indicate the importance of not only transition, but also crossflow transition on rotor and fuselage aerodynamic behavior.