| The large-scale change of turbine speed of turboshaft engine can improve the economy and multi-purpose of the rotary wing machine,but the large-scale decrease or increase of turbine speed will inevitably lead to the rotor working at a large impact angle.The variable geometry turbine can effectively solve the impact angle problem by adjusting the guide vane angle.At present,the domestic research on variable geometry turbine technology is mostly aimed at the end wall loss of guide vane under different installation angles,and the research is mainly based on marine gas turbine,lacking the analysis of the overall parameter change in the process of guide vane rotation.Therefore,the study on the variation of the overall parameters and losses with the rotation angle during the guide vane rotation of the variable geometry turbine can lay a technical foundation for the further development of the variable geometry power turbine technology and the successful application of the variable geometry technology in the turbine shaft power turbine.Firstly,three-dimensional UG software is used to design the variable geometry turbine adjustable fan cascade test piece,and the design method of the guide vane and the matching of the whole set of external transmission mechanism in the transitional test is described in detail.The influence of the clearance fit mode of the variable geometry turbine adjustable guide vane rocker and the connecting rod on the rotation of the guide vane is analyzed by three-dimensional motion simulation.The results show that the clearance fit mode causes the inconsistency of the angle of each guide vane,and the maximum angle deviation is 0.126° in the process of 0° to-5° rotation.Subsequently,the transition state test of the adjustable fan cascade based on the guide vane rotation was carried out.The transient data of the guide vane rotation from 0° to-5° and from 0° to 6° in the test were collected and compared with the numerical calculation using the dynamic mesh technology.The variation trend of the end wall pressure at the position of 55.2%axial chord length downstream of the rotating shaft with the guide vane rotation was emphatically analyzed.The experimental and numerical results show that during the rotation of the guide vane from 0° to-5°,the Mach number at the outlet of the guide vane decreases by 2.2% with linear variation,and the total pressure loss coefficient at the outlet of the guide vane increases by 37.3% with parabolic variation.During the rotation of the guide vane from0° to 6°,the Mach number at the outlet of the guide vane increases by 1.5% a linear change,and the total pressure loss coefficient at the outlet of the guide vane decreases by 15.8% with a parabolic change.Finally,based on the first stage power turbine of a certain type of turboshaft engine modified and optimized,the influence of guide vane rotation on the performance of variable geometry turbine in stage environment was studied by using dynamic mesh technology.The results show that when the guide vane rotates from 0° to 6°,the stage efficiency of variable geometry turbine increases by 0.5% in the form of parabola,the relative flow angle of rotor inlet increases by 13.5°,and the relative flow angle of rotor outlet increases by0.4° in the form of parabola.The flow rate of variable geometry turbine stage is greatly affected by the guide vane rotation.During the guide vane rotation from 0° to 6°,the flow rate at the rotor outlet increases by 11.3% with multi-stage step change,while during the guide vane rotation from 0° to-5°,it decreases by 12% with the same change rule.Based on the research results of transition state characteristics of variable geometry turbine with guide vane rotation,including the variation of flow rate,efficiency,relative flow angle between inlet and outlet of rotor blade with guide vane rotation,this paper can provide some reference for the application of variable geometry turbine aerodynamic technology in turboshaft engine power turbine. |
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