Investigation On The Redesign And Flow Analysis Of Mixed Flow Turbine With Partly Rotary Vane

With strict emission regulations being issued and implemented,such as Europe 6 and China 6,automobile engines are facing unprecedented pressure and challenges.The turbocharger becomes the primary choice as an important technique used for power enforcement,emission reduction and efficiency improvement.The mixed-flow turbine with adjustable guide vanes is chosen by most of automobile enterprises because of the adjustable and adaptable characteristics.Due to the tip clearance in the conventional adjustable guide vanes,the flow loss resulting from the tip leakage severely affected the performance of mixed-flow and engine.Therefore,controlling leak flow by reducing or eliminating tip clearance has attracted much attention.Based on previous preliminary proposal for previous partly rotational adjustable guide vane,this paper compares the performance of full rotational guide vane with or without tip clearance in forepart and rear part through numerical methods calibrated by experimental data,and several parameters influencing the performance of adjustable guide vanes are studied.The main content including:(1)The forepart rotational proposal has more advantages by comparing and analyzing the previous proposal of forepart and rear part rotational guide vane,but the flow capacity and efficiency can not be improved equitably.Therefore,further optimization is required in vane installment angles of fixed part to improve efficiency on the basis of extending flow capacity.(2)The gap size and aerodynamic performance are optimized by comparing the influence of different rotor/stator gap sizes in adjustable guide vane on the performance and flow flied.(3)The proposal with linear decreasing tip clearance has more advantages by comparing the influence of different tip clearances and distributions in rotational part on the performance and flow field.(4)Taking into account of key parameters of tip installment angles in fixed-part,rotor/stator gap sizes in adjustable guide vane,different tip clearances and distributions in rotational part,this paper optimizes the design of adjustable rotational guide vane in forepart,the efficiency of which is improved by 5.66% with respect to small opening,1.18% with respect to big opening.(5)This paper studied the influence of different rotor/stator ratios on the performance and flow field,and found that the tip enclosed area became larger as the rotating shaft coming closer to the leading edge.The chord length of clearance leak part became shorter,which reduced the leakage flow loss with the flow adjustment ability decreasing.The rotating shaft coming closer to the trailing edge has the opposite results.(6)The pressure surface profile is insensitive to the turbine performance,but the suction surface profile has a significant influence on the turbine performance by modifying the suction and pressure surface profiles in rotational forepart.Therefore,the manufacturing cost can be reduced and the flow rate increases by cutting the pressure surface thickness while maintaining a slight decreasing efficiency.(7)This paper developed three-dimensional blade design by comparing stacking proposals with different spanwise orientations in fixed part.The turbine flow ability and efficiency is improved when the spanwise stacking proposal is adopted,and larger spanwise angles lead to better ability and efficiency.