An Investigation of Turbulence Modeling in Transonic Fans Including a Novel Implementation of an Implicit k–ε Turbulence Model

An explicit Navier–Stokes solver has been written with the option of using one of two types of turbulence model. One is the Baldwin–Lomax algebraic model and the other is an implicit k–ε model which has been coupled with the explicit Navier–Stokes solver in a novel way. This type of coupling, which uses two different solution methods, is unique and combines the overall robustness of the implicit k–ε solver with the simplicity of the explicit solver. The resulting code has been applied to the solution of the flow in a transonic fan rotor, which has been experimentally investigated by Wennerstrom. Five separate solutions, each identical except for the turbulence modeling details, have been obtained and compared with the experimental results. The five different turbulence models run were: the standard Baldwin–Lomax model both with and without wall functions, the Baldwin–Lomax model with modified constants and wall functions, a standard k–ε model, and an extended k–ε model, which accounts for multiple time scales by adding an extra term to the dissipation equation. In general, as the model includes more of the physics, the computed shock position becomes closer to the experimental results.