Leon Hu

Multi-Disciplinary Multi-Point Optimization of a Turbocharger Compressor Wheel

The paper describes the application of an optimization method to the redesign of a turbocharger compressor wheel. The starting design presents quite high performance. Previous attempts to improve this design have shown it difficult to increase aerodynamic performance without compromising mechanical stress levels.The optimization methodology relies on the combination of a genetic algorithm, a neural network, a database, and user generated objective functions. The originality of the paper is that the optimization is not only coupled to a CFD solver, but also to a CSM solver, so that mechanical stresses can be included in the optimization objectives. A parametric model of the solid sector of the blade, back plate and bore zone is built and included in the optimization. The challenging turbocharger test case has allowed gaining experience with design objectives of different nature. The results show that the optimization has been able to improve the aero performance, while also decreasing the peak mechanical stress levels significantly.Copyright

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.