Study on Aerodynamic Characteristics of Variable Geometry Turbine Adjustable Guide Vane under Instantaneous Rotation
To investigate the transition state performance of single-stage variable geometry turbine(VGT)in the process of guide vane rotation,the unsteady numerical calculation of a power turbine was carried out,the dynamic mesh technology was used to realize the change of guide vane rotation angle,and the turbine performance during the transition process of the guide vane channel opening or closing was analyzed.The results show that when the guide vane angle changes from 0° to-5°,the single-stage turbine efficiency gradually decreases by 1.6％;from 0° to 6°,it gradually increases by 0.5％;the mass flow rate and the absolute flow angle at the outlet of the guide vane change nearly linearly with the change of the rotation angle,while the relative flow angle,entropy increase,efficiency and total pressure loss at the outlet of the rotor blade show parabolic changes with the change of the rotation angle;in the transition state,the change of the loss in the flow field of the guide vane is mainly affected by the leakage vortex at the upper and lower end walls,and the change of the entropy increase at the outlet of the rotor blade is mainly affected by the leakage vortex at the suction side of the rotor blade and the lower passage vortex which is the main reason for the change of entropy increase.
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