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为了了解和掌握一种具有直通式冷气预旋进气系统的小型燃气轮机涡轮转子叶片的流场,在旋转雷诺数Reθ=4.66×106和冷却空气的无量纲质量流量Cw=1750时改变预旋角θ的大小,使其在15°～90°变化,通过数值研究得到了预旋角对涡轮盘腔、连管和涡轮叶片内冷却空气的流动以及叶栅通道中燃气的流动的影响。结果表明:(1)预旋角的变化会改变涡轮盘腔、连管和涡轮叶片冷气进口附近局部区域的流场,但是对涡轮叶片内其它区域和叶栅通道中的流动基本没有影响。(2)随着预旋角的增大,涡轮盘腔内预旋进气冷气射流的轴向穿透深度先增大后减小;当θ<45°时冷却空气沿外围屏流向转盘接收孔,而当θ>45°时冷却空气沿内围屏流向转盘接收孔;气流的周向速度随着预旋角的增大而减小。(3)垂直进气时连管内存在多个回流区和很大的涡流,流动损失较大,而采用预旋进气能够减弱或消除这些流动结构,存在最优预旋角θopt,θopt≈45°,此时连管的有效流通面积最大。
In order to understand and grasp the flow field of a small gas turbine turbine rotor blade with a straight-through cooled pre-priming intake system, the pre-rotation angle was varied at a Reynolds number of Reθ = 4.66 × 106 and a non-dimensional mass flow of cooling air of Cw = 1750 θ, which makes it change from 15 ° to 90 °. The effect of pre-rotation angle on the cooling air flow in the turbine disk chamber, connecting pipe and turbine blade and the gas flow in the cascade passage is obtained by numerical analysis. The results show that: (1) The change of pre-rotation angle will change the flow field in the local area near the inlet of the turbine disk, the connecting pipe and the turbine blades. However, it has no influence on the flow in other regions of the turbine blade and the cascade. (2) With the pre-rotation angle increasing, the axial penetration depth of the precooled intake air-cooled jet in the turbine disk first increases and then decreases; when θ <45 °, the cooling air flows along the peripheral screen to the turntable receiving hole , While when θ> 45 °, the cooling air flows along the inner screen to the turntable receiving hole; and the circumferential velocity of the air flow decreases with the increase of the prerotation angle. (3) There are multiple recirculation zones and large eddy currents in the pipe when vertical intake, and the flow loss is large. Pre-spin intake can weaken or eliminate these flow structures. There exists the optimal prerotation θopt, θopt≈45 °, at this time even with the effective circulation area of the largest tube.