Influence of Twisted Nozzle Vane of VNT on Turbine Blade Excitation
Turbine blade high-cycle fatigue(HCF)limits the service life of turbochargers,which is particularly obvious in var-iable nozzle turbochargers.Aiming at the problem that the VNT radial turbine of a 0.6 L two-stroke gasoline engine turbo-charger is prone to HCF failure during operation,a twisted nozzle vane blade type was designed and the effect of twisted nozzle vane on the turbine flow field and blade excitation was studied by using numerical simulation.The results show that the clock-wise twisted nozzle vane can reduce the interference effect between the nozzle guide vane outlet and the leading edge of the tur-bine blade and the counterclockwise twisted nozzle vane will enhance the interference effect.Compared with the original sym-metric vane,the high-temperature and high-pressure gas flow into turbocharger is inclined after passing through the clockwise twisted vane,the gas flow excitation force is dispersed,and hence the effect on the leading edge of downstream turbine blades weakens.At the same time,due to the reduction of the pressure gradient in the turbine blade clearance,the intensity of clear-ance leakage flow decreases,and the excitation amplitude in the high excitation region of the blade also decreases.The study comprehensively considers the changing trends of turbine efficiency and blade excitation force,and determines that the nozzle vane twist angle of 4°is the most reasonable.The optimal solution reduces the maximum vibrational stress of blades by 64%without affecting turbine performance.
万方数据
维普
