Effects Of Variable Geometry Turbine Stage Aerodynamic Performance

As traditional fixed geometry turbine can not keep a good running performance under variable working condition, variable geometry turbo technology can regulate the gas turbine performance in good operating point so that the gas turbine to better match the performance between the various components and the gas turbine can be run on a good working point in different conditions. However the ends of the guide vane variable geometry turbine set aside enough clearance and clearance leakage flow which cause great changes of the tip fluid flow , but the overall performance of the losses caused by the turbine will have a greater impact. So, the research to the tip clearance flow and losses generated by the mechanism and upstream vortex flow on rotor blades is of great significance. In addition, the real flow inside of the turbine was presented through the calculation of unsteady .In this paper, the first stage vanes of a certain type of variable geometry power turbine study guide vanes can be transferred, using numerical simulation methods to analyze flow field characteristics of three kinds of guide vane scheme and analyzes the cascade flow passage vortex system of the formation and development, to explore the effect of flow loss on the turbine efficiency. First of all, under the same boundary conditions, Contrasting the flow structure and aerodynamic parameters of the three kind of case including gapless guide vanes, gap guide vanes and the vanes with drive shaft on the end zone and the main areas.Study drew gap leakage flow field characteristics and the impact of development within the vortex and loss distribution of the flow channel by the drive shaft. The results showed that clearance leakage can be suppressed and make the guide vane outlet parameters change by drive shaft. At the same time, drive shaft affect the structure of vortex of rotor blades.Contrast clearance program guide vanes, turbine efficiency is improved.Then, steady simulation method in the study of variable geometry turbine is widespread, but which ignored the unsteady flow phenomena inside the turbine. To address this deficiency, the paper conducted numerical simulation unsteady for the program of guide vane with drive shaft on the basis of steady numerical simulation results. It analysis of the rotor-stator interactions and the unsteady flow inside the variable geometry turbine. The results show that the unsteady calculation can accurately simulate the guide vane leakage vortex, passage vortex and the wake of the spread and development in turbine stage.There is interference between the upstream and downstream vortices, cyclical fluctuations in rotor blades outlet and others unsteady phenomena.Finally, changing the angle of the vanes installation method to study the variable geometry turbine characteristics in this paper. And several models of guide vanes which rotate with the degree at - 6°, - 4 °, 0 °, 4 ° and 6 ° were calculated. On the basis of numerical calculation results, the paper analyses the changing of pressure distribution and the loss distribution when the vane rotating. Study drew leakage vortex developments and the impact on the rotor blades leakage vortex lines on the different angles.