Numerical investigation of the split sliding guide vane for a variable nozzle turbine

The “swing” type guide vane has been widely used to control flow capacity in variable nozzle turbines. One disadvantage of these variable nozzle turbines is the drastic drop in stage efficiency that is caused by nozzle leakage flow when the engine operates at “low-end” conditions. In the present work, a novel split sliding guide vane has been proposed to improve turbine stage performance by mitigating the nozzle leakage flow. The design idea, geometry structure, and actuating method of split sliding guide vane are described in detail. A series of steady numerical simulations were performed on both baseline and split sliding guide vane turbines to verify the effectiveness of the split sliding guide vane, at three representative nozzle openings. Simulation results indicate that split sliding guide vane can effectively improve turbine peak efficiency up to 8% at 6% nozzle opening. In addition, unsteady simulations were also carried out to investigate the interaction between rotor and nozzle, and the aerodynamic loading fluctuations on rotor blades were compared between split sliding guide vane and base model.