Experimental and numerical investigation of periodic downstream potential flow on the behavior of boundary layer of high-lift low-pressure turbine blade

• Published in: Aerospace science and technology Vol. 123; p. 107453
• Main Authors: Sun, Shuang, Wu, Xingshuang, Huang, Zhen, Hu, Xizhuo, Zhang, Peng, Kong, Qingguo
• Format: Journal Article
• Language: English
• Published: Elsevier Masson SAS 01.04.2022
• ISSN: 1270-9638; 1626-3219
• DOI: 10.1016/j.ast.2022.107453

A high-lift and compact design can reduce the weight of low-pressure Turbine (LPT), but increase the complexity of the boundary layer flow of LPT, which affects the LPT blade profile loss. This study experimentally and numerically investigates the boundary layer of a high lift low-pressure turbine blade with a periodic downstream pressure field. The investigations are conducted at inflow Reynolds numbers of 87000. Experiments are performed on a low-speed cascade test rig, and CFD simulations are used to create a time-averaged and instantaneous flow field. With a downstream potential flow field, the velocity field and pressure field of the boundary layer are found to fluctuate periodically. Due to the viscous free shear layer, the velocity at the edge of the shear layer and the wall shear stress also exhibit a phase difference. By decomposing and reconstructing the instantaneous flow field, the downstream potential flow is shown to destabilize the separation bubble and induce the vortex-shedding earlier, causing transition to occur earlier, increasing profile losses. The disturbance energy distribution of the boundary layer is more broadened and migrates into smaller scale vortices. However, the downstream potential flow does not change the dominant role of K-H instability affecting transition.