支撑板型线和径向倾斜设计对燃气轮机排气扩压器气动性能的影响

Effects of Airfoil and Radial Tilt Design of Struts on Aerodynamic Performance of Gas Turbine Exhaust Diffuser

关键词:  燃气轮机  排气扩压器  支撑板  气动性能  数值模拟

Key words:  Gas turbine  Exhaust diffuser  Strut  Aerodynamic performance  Numerical simulation

摘要:

支撑板结构设计直接影响燃气轮机排气扩压器的流场结构和气动性能。在验证数值方法可靠的基础上，采用求解三维Reynolds-Averaged Navier-Stokes（RANS）和Realizable k-ε湍流模型的方法，对带进气导叶和支撑板的排气扩压器模型进行了研究，探究在四种进气预旋下，支撑板截面型线以及本文提出的支撑板径向倾斜设计方案对排气扩压器气动性能的影响。结果表明：进气预旋和支撑板设计方式相同时，截面型线更薄的支撑板更易导致流体在支撑板附近的分离及更大范围的尾迹流，从而增大总压损失；支撑板截面形状相同时，与径向垂直设计相比，支撑板采用径向倾斜设计使得排气扩压器通道面积变化更加平缓，从而使得在四种进气预旋下，排气扩压器的总压损失系数下降7%~20%。当支撑板截面型线宽长比（d/C）为0.2时，相对于径向垂直设计，支撑板采用径向倾斜设计方式的排气扩压器静压恢复系数在进气预旋φˉ=0.35和φˉ=0.64时分别提升了4.7%和3.8%；但在支撑板截面型线宽长比（d/C）为0.12和0.175时，支撑板采用径向倾斜设计方式会降低排气扩压器在进气预旋φˉ=0.64和φˉ=1.00时的静压恢复性能。

Abstract:

Strut structure design directly affects the flow field and aerodynamic performance of gas turbine exhaust diffuser. Based on the reliability of the numerical method， the exhaust diffuser model with inlet guide vanes and struts was calculated by solving the three-dimensional Reynolds-Averaged Navier-Stokes （RANS） and Realizable k-ε turbulence models， exploring the effects of the cross-sectional shape and tilt design of the strut on the aerodynamic performance of the exhaust diffuser under four kinds of inlet pre-swirl. The results show that when the inlet pre-swirl and the design method of strut are the same， the strut with thinner profile line is more likely to cause the separation of fluid near the strut and the larger wake flow， increasing the total pressure loss. When the cross-sectional shape of the strut is the same， compared with the radial vertical design of the strut， the radial tilt design of the strut makes the change of the passage area of the exhaust diffuser more gentle， so that the total pressure loss coefficient of the exhaust diffuser decreases by 7%~20% under the four types of inlet pre-swirl. When the aspect ratio（d/C） of strut section line is 0.2， relative to the radial vertical design， the static pressure recovery coefficient of the exhaust diffuser with tilt design of strut increases by 4.7% and 3.8% respectively when the inlet pre-swirl is equal to 0.35 and 0.64， however， when the aspect ratio（d/C） of the strut section line is 0.12 and 0.175， the strut tilting design reduces the static pressure recovery performance of the exhaust diffuser when the inlet pre-swirl is equal to 0.64 and 1.00.