A biomimetic design of steam turbine blade to improve aerodynamic performance

The complex flow field at low load will affect the aerodynamic performance of steam turbine. To improve the performance in low mass-flow condition, we proposed a design of bio-inspired steam turbine blade with biomimetic bumps on suction side. We built a series of biomimetic blades based on a last stage rotor blade of nuclear low-pressure to analyze the function of the bump. The numerical simulation results declared that bumps generated streamwise vortices. There existed a region with low-pressure on suction side which was suitable for vortices to be generated and to develop. Under the influence of streamwise vortex, the steam flow near suction side was restricted in a low velocity. The energy exchange between blade and the main flow was blocked. The pressure on suction side decreased. Therefore, the performance of blade was improved, reflecting in the raised output torque. The output torque of optimum biomimetic blade raised from a negative value-26.31 N m to a positive value 2.13 N m in low mass-flow condition. To explore the function of bump, we also built a blade with vortex generators at the same place. The result shows that the bumps on blade cause less pressure loss for the turbine passage and the vortices generated by them influenced wider region in the flow field. The current work provided a new design route for modifying turbine rotor by flow control structure.

Automated summary

The complex flow field at low load has a significant impact on the aerodynamic performance of steam turbines. To improve performance under low mass-flow conditions, a design of bio-inspired steam turbine blades with biomimetic bumps on the suction side was proposed. Numerical simulation results showed that the bumps generated streamwise vortices, leading to a decrease in pressure on the suction side of the blade. This resulted in improved performance, reflected in the increased output torque.