Hydraulic Turbine Stay Ring Flow Alignment
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Solution Overview
Problem
Hydraulic turbines with bell-mouthed type stay rings experience significant energy loss due to varying flow angles and geometrical angles at the inlet of stay vanes, making it difficult to modify existing stay vanes effectively while maintaining strength, and thus reducing efficiency.
Innovation Solution
A stay ring design with inclined upper and lower walls and straightening bodies along the inner surfaces near the inlet to reduce the height of the flow channel and align the water flow, allowing for adjustable guide vanes to minimize the velocity component in the elevating direction, thereby reducing energy loss and improving efficiency without extensive modification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If bell-mouthed type stay ring is used to smoothly link wall surfaces, then structural continuity is improved, but flow angle mismatch at stay vane inlet causes energy loss
Solution Approach 1:
The stay ring transitions from a uniform bell-mouthed profile to a composite structure with different profile types in different regions. The upper and lower walls have different profiles: the upper wall maintains a bell-mouthed profile for structural continuity, while the lower wall uses a parallel profile to align flow angles with stay vane inlets, reducing energy loss. This local differentiation resolves the contradiction between structural continuity and flow efficiency.
2Loss of energy
If stay vanes are extensively modified to match varying flow angles, then energy loss is reduced, but structural strength is compromised
Solution Approach 1:
Instead of modifying the stay vane geometry extensively, the invention changes the flow parameters by designing the upper and lower walls with different profiles. This alters the flow angle distribution to match the existing stay vane inlet angles, reducing energy loss without compromising the structural strength of the stay vanes.
3Loss of energy
If parallel type stay ring is used to maintain consistent flow angle, then energy loss is reduced, but smooth linkage of wall surfaces is lost
Solution Approach 1:
The invention introduces asymmetry in the stay ring structure by using different profiles for the upper and lower walls. The upper wall uses a bell-mouthed profile while the lower wall uses a parallel profile, creating an asymmetric composite structure that achieves both smooth wall linkage and consistent flow angles for reduced energy loss.
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
The proposed design significantly reduces energy loss and improves the operational efficiency of hydraulic turbines by aligning flow and geometrical angles at the inlet of stay vanes, enhancing power generation while maintaining structural integrity.
Implementation Method 1
the upper wall and the lower wall are inclined so as to reduce height of the ring-shaped flow channel toward outlet
Implementation Method 2
straightening bodies are arranged along inner surfaces of the upper wall and the lower wall at least near inlet end to reduce inclination of water flow in the stay ring
Implementation Method 3
the potential energy of the water is converted into rotational energy before the water flows out to a lower reservoir by way of the draft tube
Data Source
AI summary
A stay ring of a hydraulic turbine has: a ring-shaped upper wall, a ring-shaped lower wall arranged below the upper wall forming a ring-shaped flow channel between the upper wall and the lower wall; and stay vanes arranged in array with spaces in a peripheral direction in the ring-shaped flow channel and rigidly secured to the upper and lower walls. The upper wall and the lower wall are inclined so as to reduce height of the ring-shaped flow channel toward outlet at least near inlet end thereof. The straightening bodies are arranged along inner surfaces of the upper wall and the lower wall at least near inlet end to reduce inclination of water flow in the stay ring.