High-lift Low Pressure Turbine Blade Linear Cascade Test

In order to increase the thrust-weight ratio of turbofan engine, more and more low pressure turbine blade are designed with high lift. However, the resultant strong adverse pressure gradients on the suction side of the blades increase the possibility of laminar boundary layer separation, particularly under the low Reynolds number conditions, which lead to high profile loss. Boundary layer flow state and the profile loss is closely related. Clearing blade boundary layer flow state, is very necessary in the process of blade design. In this paper, a certain type of high lift blade aerodynamic are investigated about aerodynamic performance, based on linear cascade wind tunnel test. The test conditions considered were for four different Reynolds numbers and different wake reduced frequencies. Blade surface loading distribution,total pressure coefficient and outlet flow deviation angle are measured at different conditions. And the design of the test section, test device and test method are emphatically introduced.Through the Fluent flow field simulation software, the blade passage flow field are simulated at test conditions. The Transition SST model is used in this simulation. This model couple the Langtry-Menter transition model and SST k-co turbulence model. The blade aerodynamic performance is analysised combine with the test and numerical simulation results. This paper mainly consider the state of the boundary layer when wakes are propagating through the blade passages.It's found that separation bubble appear on the high lift blade suction surface. Separation bubble length grow with decreasing Reynolds number, which cause higher loss. Outlet airflow direction shifts towards the blade suction surface with decreasing Reynolds number. The designed wake generator can accurately simulate the upstream cascade wake. Unsteady wake effects at low Reynolds number conditions is effective to suppress the separation bubble generation. Boundary layer state may return to steady state between the wake segments at low wake reduction frequency (fr=0.3). Boundary layer separation bubble disappear completely at the high wake reduction frequency(fr=0.6).