向心透平级内流动的数值研究

NUMERICAL INVESTIGATION OF THE FLUID FLOW INSIDE BLADE ROWS OF A RADIAL INFLOW TURBINE

本文基于三维N-S方程组,采用结构化网格,用数值方法模拟了一台75 kW微型燃气轮机中涡轮级内的流动。湍流模型采用Baldwin-Lomax模型,计算方法基于Jameson格式。结果表明:静叶流道在吸力面一侧,沿子午流线的前25％区域气流快速膨胀,而压力面在60％以后逐渐膨胀。一定的气流入口角能有效控制导叶内横向二次流动,并使得气流出口角更加均匀,其出口气流的落后角也有明显的减小。在叶轮流道内部的损失区主要集中在吸力面一侧,叶顶间隙的泄漏流动使得吸力面与叶顶间的角隅区的损失有明显加大,控制叶轮的径向间隙对控制流动损失有明显作用。

This paper presents the fluid flow pattern inside one radial inflow turbine for 75 kW micro gas turbine with three dimensional RANS equations solved by Jameson scheme in structured grids. Turbulence is enclosed with algebraic Baldwin-Lomax model. Results show that the flow accelerates within the passage enclosed by the first 25% suction surface and the later 60% pressure surface. A special inlet flow angle can control the cross flow inside the guidevane,outlet flow angle(uniform),and ruduced overtuning angle. Impeller's flow loss is accumulated near the suction side. The injection flow in the tip clearance makes the loss more evident at the suction and shroud corner. Reduced radial tip clearance will improve the impeller's flow efficiency.