CFD SIMULATIONS OF THE UNSTEADY-STATE FLOW THROUGH A 1.5-STAGE HIGH-WORK TURBINE

Abstract Behr et al. [1] have experimentally investigated the unsteady-state flow and clocking effects in a 1.5-stage high-work turbine. Their test rig had a first stator row with 36 blades, a 54-bladed rotor at 2,700 rpm, and a second stator row with 36 blades. They studied four different stator-clocking positions. The present paper computationally investigates the unsteady-state flow through the 1.5-stage turbine by performing CFD simulations with the Simcenter STAR-CCM+ software. The mathematical model of the simulations consisted of the ensemble-averaged unsteady-state mass, momentum and energy equations complemented by the SST turbulence model. The authors applied a quality assessment procedure to the computational results before comparing them to the experimental data. They reported the numerical accuracy using the Grid Convergence Index (GCI). The results showed an increase in the calculated efficiencies of the unsteady-state over the steady-state results, bringing data and simulations closer. The total pressure contours at the rotor and second stator exit planes also agreed well with the experiments. Finally, the paper includes simulations of the effects of different stator-clocking positions. The results showed a similar response to the change in stator-clocking position as the experiments.