Transonic turbine blade loading calculations using different turbulence models – effects of reflecting and non-reflecting boundary conditions

The objective of this study is to simulate the transonic gas turbine blade-to-blade compressible fluid flow. We are interested mainly in the determination of the pressure distribution around the blade. The particular blade architecture makes these simulations more complex due to the variety of phenomena induced by this flow. Our study is based on the experiment performed by Giel and colleagues. Tests were conducted in a linear cascade at the NASA Glenn Research Center. The test article was a turbine rotor with design flow turning of 136° and an axial chord of 12.7 cm. Simulations were performed on an irregular quadratic structured grid with the FLUENT software package which solves the Navier–Stokes equations by using finite volume methods. Two-dimensional stationary numerical simulations were made under turbulent conditions allowing us to compare the characteristic flow effects of Reflecting Boundary Conditions (RBC) and Non-Reflecting Boundary Conditions (NRBC) newly implemented in FLUENT 6.0. Many simulations were made to compare different turbulence models: a one equation model (Spalart–Allmaras), several two-equation models (k–ε, RNG k–ε, Realizable k–ε, SST k–ω), and a Reynolds-stress model (RSM). Also examined were the effects of the inlet turbulence intensities (0.25% and 7%), the exit Mach numbers (1.0 and 1.3) and the inlet Reynolds numbers (0.5 × 106 and 1 × 106). The results obtained show a good correlation with the experiment.