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在低进口雷诺数下,低速轴流涡轮内部可能存在复杂的边界层转捩和分离流动。准确模拟边界层转捩和流动分离对低速轴流涡轮的气动设计具有重要意义。本文以某单级低速轴流涡轮为研究对象,采用大涡模拟方法对其在进口雷诺数为20000情况下的内部流动进行了数值模拟研究,并与前期采用全层流模型、S-A模型、Abu-Ghannam&Shaw(AGS)转捩模型的模拟结果进行了对比,对比分析发现,大涡模拟结果与实验结果吻合更好,可以准确模拟该涡轮叶片吸力面的流动分离和叶片通道内的二次流动。由大涡模拟结果可以得出,静叶尾迹和分离使尾迹区的流体流动速度降低,但尾迹对流动角的影响较小。动叶入口低速微团在做周向运动的同时沿径向运动;高速微团主要沿周向运动。静叶叶片表面的分离流存在较大的由叶顶向叶根的径向的运动;动叶吸力面叶顶处也存在较大的分离流动.
At low inlet Reynolds numbers, complex boundary layer transitions and separate flows may exist inside low speed axial turbines. Accurately simulating the boundary layer transition and flow separation is of great importance to the aerodynamic design of low speed axial flow turbines. In this paper, a single-stage low-speed axial-flow turbine is taken as the research object. The large-eddy simulation method is used to simulate the internal flow under the inlet Reynolds number of 20000. -Ghannam & Shaw (AGS) transition model. Comparisons of the results show that the large-eddy simulation results are in good agreement with the experimental results, which can accurately simulate the flow separation on the suction side of the turbine blade and the secondary flow in the blade passage. From the results of large eddy simulation, it can be concluded that the wake flow and separation of stator vanes reduce the fluid flow velocity in wake region, but the influence of wake on flow angle is small. The low-velocity micelle at the inlet of the rotor moves radially while moving in the circumferential direction. The high-speed micelle moves mainly in the circumferential direction. There is a large radial movement of the separation flow on the surface of the vane blade from the top of the blade to the root of the blade. There is also a large separation flow at the top of the blade suction surface.