Numerical Analysis of Nozzle Clearance's Effect on Turbine Performance

Hu, Liangjun

doi:10.3901/cjme.2011.04.618

Cited by 22 publications

(15 citation statements)

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“…However, at 100% nozzle opening, there is almost no difference in stage efficiency between the two models. Similar results were also shown in the researches of Hu et al, 16 indicating that the MFR and performance of turbine are seriously affected by nozzle endwall clearance at nozzle small openings, while at nozzle large openings, the clearance effect will be mitigated.…”

Section: Numerical Modelsupporting

confidence: 87%

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

Yang

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part D:

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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.

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Section: Numerical Modelsupporting

confidence: 87%

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

Yang

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part D:

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“…Hu et al [1] carried out a numerical investigation of the effect of nozzle clearance on turbine performance in a VGT turbine at different open conditions and indicated that the nozzle vane's endwall clearance leakage affects the turbine performance at small open conditions. Hideaki et al [2] found similar results and indicated that the leakage flow passing the clearance, due to the pressure difference between the suction side and pressure side, goes to the pressure side from the suction side.…”

Section: Introductionmentioning

confidence: 99%

Understanding of the Interaction between Clearance Leakage Flow and Main Passage Flow in a VGT Turbine

Zhao

Yang

et al. 2014

Advances in Mechanical Engineering

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The clearance flow between the nozzle and endwall in a variable geometry turbine (VGT) has been numerically investigated to understand the clearance effect on the VGT performance and internal flow. It was found that the flow rate through turbine increases but the turbine efficiency decreases with height of clearance. Detailed flow field analyses indicated that most of the efficiency loss resulting from the leakage flow occurs at the upstream of the rotor area, that is, in the nozzle endwall clearance and between the nozzle vanes. There are two main mechanisms associated with this efficiency loss. One is due to the formation of the local vortex flow structure between the clearance flow and the main flow. The other is due to the impact of the clearance flow on the main flow after the nozzle throat. This impact reduces the span of shockwave with increased shockwave magnitude by changing the trajectory of the main flow.

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“…Hu et al [4] analyzed the effect of nozzle clearances on turbine performance numerically. For this analysis the peak efficiency point ( / = 0.68) was chosen.…”

Section: Literaturementioning

confidence: 99%

“…Such change in direction of aerodynamic torque causes difficulty in controlling the operation of actuator. Further it is preferable to always have positive torque [4,6] acting on the vanes which ensures the safety against actuator failure. While a positive torque is preferred, it is also desired that the magnitude of torque or gas loads acting on the vane are minimum to avoid excessive bending stress.…”

Section: Observationsmentioning

confidence: 99%

Numerical Investigation: Effect of Stator Vanes on Turbocharger Turbine Performance

Rapolu¹,

Balachandar²,

Kamaraj³

2014

International Journal of Rotating Machinery

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With reduced turbo lag and better transient response, the introduction of VTG stator guide vanes improved turbocharger performance at all the engine operating conditions. The VTG system accelerates and maneuvers exhaust gas flow to the turbine. Favorable flow conditions at turbine inlet created by vane shape improve turbine performance. At lower engine speed, it is observed that the pressure drop across vane system influences overall efficiency. Whereas at higher speed, the pressure drop and guide vane exit flow angle are found to determine the turbine efficiency. Successful practical operation of VTG system also depends on its ability to smoothly open and close the vanes at different gas loads. Stator vane shape greatly influences the smooth operability/controllability of vane system. In the present work, 3 symmetric vanes with differentT/Cratios and 2 asymmetric vanes are analyzed. The effect of geometric changes is studied from overall turbine performance as well as VTG system performance perspective. It is observed that symmetric vanes cause higher pressure drop at lower speeds leading to lower efficiency irrespective of the vane width. It is also observed that the pressure drop characteristics and vane exit flow angle are better with the asymmetric vanes, whereas the controllability of symmetric vanes is found to be superior. Analysis methodology is presented for achieving the best compromise between performance and controllability by the modification of vane geometric parameters through CFD simulations.

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Numerical Analysis of Nozzle Clearance's Effect on Turbine Performance

Cited by 22 publications

References 0 publications

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

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

Understanding of the Interaction between Clearance Leakage Flow and Main Passage Flow in a VGT Turbine

Numerical Investigation: Effect of Stator Vanes on Turbocharger Turbine Performance

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