What's inside?
This paper investigates the effects of blade loading and lean angle at the runner inlet on internal flow and loss within a Francis turbine runner. A new runner is designed using the 3D Inverse Design Method and Computational Fluid Dynamics (CFD) to enhance the turbine performance.
The study reveals that pressure gradients and centrifugal forces generate spanwise secondary flow, which can be minimized by designing with after-loading at every blade span.
A positive blade lean angle, inclining forward in the direction of rotation, effectively reduces pressure gradients and controls secondary flow. The performance of the newly optimized runner confirms the benefits of these design adjustments. These findings and the optimization method are valuable for improving turbine performance.
Using this knowledge, designers can optimize the runner shape more quickly and cost-effectively compared to traditional design methods that rely on manual operations and control of secondary flow.
In this publication, you will:
- Discover how reduced static pressure gradient and the centrifugal forces
induce the spanwise secondary flow on the runner vanes. - Learn how aft-loading distribution on a runner is effective in minimizing the secondary flow and improving the turbine performance.
- See how positive blade lean angle, i.e., band side forward inclination in
the rotating direction, can reduce the spanwise secondary flow.
