时序效应对高负荷低压涡轮边界层流动的影响研究

In multi-stage turbines, the clocking effect and calming effect would have significant impacts on the internal flow and aerodynamic efficiency. Taking a two-stage highly-loaded low-pressure turbine as the research object, and the high-precision large eddy simulation (LES) method was utilized to simulate the unsteady flow fields at the mid-section of the turbine blade. The time-averaged flow field, time-averaged aerodynamic performance and unsteady evolution of the boundary layer flow in the second-stage stator under five different stator clocking positions were analyzed. Results show that the different clocking positions of the first-stage stator have a significant impact on the total pressure loss of the second-stage stator, with changes in total pressure loss reaching up to 20% across different clocking positions. The differences in flows under different clocking positions are mainly attributed to the transport process of the wake in the blade rows, as well as changes in boundary layer transition induced by the interaction between the wake and boundary layer. When the wake of the first-stage stator hits the leading edge of the second-stage sta-tor, the separation zone on the suction surface of the second-stage stator is significantly reduced, resulting in the minimum total pressure loss. Conversely, when the wake of the first-stage stator enters the blade passage from a position approximately 40% of the pitch distance from the suction side of the second-stage stator, multiple separation bubbles appear at the rear part of the suction side of the second-stage stator during a rotor passing period, leading to the maximum time-averaged total pressure loss.