变截面支撑板提升燃气轮机排气扩压器气动性能的研究

Study of Variable Section Struts to Improve Aerodynamic Performance of Gas Turbine Exhaust Diffusers

为提升燃气轮机排气扩压器的气动性能,文章设计了一种变截面弯扭锥形支撑板。采用数值求解三维Reynolds-Averaged Navier-Stokes(RANS)的方法在两种进气旋流角条件下对比分析了原始结构支撑板和变截面弯扭锥形支撑板对排气扩压器气动性能的影响。研究表明:进气旋流角为16°和28°时,与原始结构支撑板相比,变截面弯扭锥形支撑板一方面通过其后掠锥形设计使得气流对支撑板前缘的冲击沿轴向逐渐发生,另一方面通过前缘的弯度设计减小了相对进气攻角,使得排气扩压器内流动分离减弱,进而减小排气扩压器的总压损失系数。进气旋流角为28°时,变截面支撑板还可以显著增加排气扩压器的动压转化系数。变截面支撑板在进气旋流角分别为16°和28°时使得排气扩压器的静压恢复系数相对提升4.8%和30%。所提出的变截面弯扭锥形支撑板有效提升了排气扩压器的静压恢复性能。

To improve the aerodynamic performance of the gas turbine exhaust diffuser,a twisted and tapered strut with a variable cross-section is designed in this paper.The effects of the original strut and the variable cross-section strut on the aerodynamic performance of the gas turbine exhaust diffuser are comparatively analyzed by numerically solving the three-dimensional Reynolds-Averaged Navier-Stokes(RANS)method at two inlet swirl angles.The study shows that:when the inlet swirl angle is 16°and 28°,compared with the original strut,The variable cross-section strut,on the one hand,makes the impact of the airflow on the leading edge of the strut occur gradually in the axial direction by its swept-back design,and on the other hand,reduces the relative inlet angle of attack by the curvature of the leading edge,which makes the flow separation in the exhaust diffuser weaker,and thus reduces the total pressure loss coefficient of the exhaust diffuser.At an inlet swirl angle of 28°,the variable cross-section strut can also significantly increase the dynamic pressure conversion coefficient of the exhaust diffuser.The static pressure recovery coefficients of the exhaust diffuser with the variable-section strut are relatively increased by 4.8%and 30%at inlet swirl angles of 16°and 28°,respectively.The proposed twisted and tapered strut with variable cross-section effectively improves the static pressure recovery performance of the exhaust diffuser.