Sensitivity of RANS-Based Transition Models on Compressor Rotor Aerodynamics

The sensitivity of the transition model (γ–Reθ) to the aerodynamic characteristics of a compressor rotor was examined using a commercial RANS program. The single-stage compressor NASA Stage 35 was modeled for this purpose. Combinations of turbulence models paired with the transition model were first evaluated on a flat plate. The predictions by the Baseline Explicit Algebraic Reynolds Stress Model (BSL EARSM) with the transition model showed promising results, and this combination was therefore applied to the compressor stage. The detailed flow characteristics and resulting loss coefficients of the compressor rotor were compared among the combinations with and without the transition model. With the transition model, the shock location shifted downstream and became more oblique, and was followed by local flow acceleration downstream of the shock. Regarding the aerodynamic losses, implementing the transition model resulted in a 10–16% underprediction of stagnation pressure, enthalpy, and entropy loss coefficients relative to the predictions without the transition model. Changes in the coefficient of secondary kinetic energy were modest for the rotor. In contrast, the loss coefficient of turbulent kinetic energy was overpredicted by 1.6% when the BSL EARSM was coupled with the transition model. For off-design performance, especially near-surge conditions, the predictions with and without the transition model showed noticeable deviations from the experimental data.