Guide Vane Projections for Hydraulic Leakage Control
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Solution Overview
Problem
The existing guide vanes in Francis-type pump turbines experience hydraulic power loss due to gap flows between the vanes and covers, leading to turbulent flows and increased energy loss, which cannot be effectively reduced without risking interference or foreign object entrapment by minimizing the gap size.
Innovation Solution
The guide vane design incorporates internal-diameter and external-diameter side projections with arcuate shapes that extend along the rotation trajectory, increasing the contact area with gap flows and reducing leakage, while maintaining sufficient clearance to avoid interference with the runner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the gap between the guide vane and covers is reduced to minimize leakage, then hydraulic power loss is reduced, but the risk of interference between the guide vane and covers increases
Solution Approach 1:
A seal member (brush seal or lip seal) is introduced as an intermediary element between the guide vane and the covers. This seal member extends from the cover toward the guide vane, creating a sealing interface that reduces gap flow without requiring the guide vane to be in direct contact with the cover, thus preventing interference while minimizing leakage.
Solution Approach 2:
The invention changes the sealing parameter from relying solely on mechanical contact (zero gap) to using a flexible seal member that can adapt to the gap dimensions. The seal member's flexibility and contact pressure parameters are optimized to achieve effective sealing without causing interference or wear on the rotating guide vane.
2Loss of energy
If the gap between the guide vane and covers is reduced to minimize leakage, then hydraulic power loss is reduced, but the risk of foreign object entrapment increases
Solution Approach 1:
The seal member acts as an intermediary that creates a controlled sealing interface. Its flexible nature allows it to accommodate small foreign objects without causing entrapment, while still maintaining effective sealing to reduce gap flow and hydraulic power loss.
3Loss of energy
If projections are added to the guide vane to reduce gap flow, then hydraulic power loss is reduced, but the device complexity increases
Solution Approach 1:
Instead of modifying the guide vane structure with projections, the invention introduces a separate seal member as an intermediary component. This approach achieves the same gap flow reduction effect without complicating the guide vane design, as the seal member is a standalone component that can be independently selected and replaced.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively decreases water leakage between blade faces, reducing hydraulic power loss and turbulent flow generation, while ensuring reliable operation and minimizing the risk of foreign object entrapment.
Implementation Method 1
A projection having a projection rear end of an arcuate shape, which projection rear end is formed to extend along a rotation trajectory which is drawn by a trailing edge when the vane body is rotated
Data Source
AI summary
A vane body of a guide vane includes a leading edge, and a trailing edge which is located closer to a runner than the leading edge, when located radially outside the runner. A projection extending in a direction from the trailing edge toward the leading edge is provided on an internal-diameter side blade face of the vane body, at least in any one of one side area of the internal-diameter side blade face and the other side area thereof in an axial direction of a guide vane rotation shaft, the internal-diameter side blade face being disposed on a side of the runner. The projection has a projection rear end of an arcuate shape, which projection rear end is formed to extend along a rotation trajectory which is drawn by the trailing edge when the vane body is rotated about the guide vane rotation shaft.