Effect of the Wavy Leading Edge to Aerodynamic Performance Improvement in A Nuclear Steam Turbine Last Stage Blade
Abstract
The aerodynamic performance of a steam turbine degrades greatly when working at low load. One of the main reasons is deemed to be the flow separation. In this paper, two structures of wavy leading edge inspired in the humpback whale flipper are designed to suppress the separation: one with tubercles and one with invaginations. The sensitivity analysis of different blade heights reveals that two types of wavy leading edge bring their best enhancement under different range of negative attack angle. The design of structure adapted to the changing blade shape advances that the streamwise vortices generated by wavy leading edge can improve performance via expanding high pressure region on blades. The evolution of vortices influenced deeply by the radial velocity is much different from that in wings and aerofoils. The wheel power of turbine with the biomimetic blade is increased by 7.8% compared with the original design. The findings in our study can be used to guide the design.