Francis Pump-Turbine Refurbishment via Guide Vane Incidence Correction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The refurbishment of Francis pump-turbines often results in a lack of incidence between the water flow angles and the geometric angles of the stay vanes, leading to increased pressure losses and reduced performance, due to the difficulty in modifying the stay vanes without weakening the mechanical structure.

Innovation Solution

A method that involves attaching a deflector to the flange rings and adjusting the guide vanes to correct the incidence, while maintaining the original geometry of the stay vanes, by reducing the height of the first channels and adapting the distributor and runner heights to enhance the radial direction of the water flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the guide vanes are modified to correct the lack of incidence, then the performance is improved, but the stay vanes become too radial causing additional pressure losses

Engineering Contradiction:

Improvepump-turbine performanceVSAvoidpressure losses

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The invention divides the pre-distributor into two independent parts: the stay vanes (which remain fixed and maintain structural integrity) and the guide vanes (which are modified to correct flow incidence). This segmentation allows each component to be optimized independently - the guide vanes can be reshaped to improve flow alignment without affecting the structural function of the stay vanes.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention applies local quality by modifying only the geometric angle of the guide vanes at their leading edge, while keeping the stay vanes unchanged. This localized modification targets specifically the flow incidence issue without requiring global structural changes that would compromise mechanical strength.

Inventive Principle:

Principle #3Local quality

2Ease of operation

If the interior geometric angle of the stay vanes is reduced to correct the lack of incidence, then the flow alignment is improved, but the mechanical strength of the structure is weakened

Engineering Contradiction:

Improveflow alignmentVSAvoidmechanical strength of pre-distributor

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The invention separates the functions of flow guidance (guide vanes) and structural support (stay vanes). By modifying only the guide vanes and leaving the stay vanes unchanged, the structural integrity is preserved while still achieving improved flow alignment through the guide vane geometry modifications.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The guide vanes act as an intermediary element that transfers the corrected flow direction from the distributor to the runner, allowing the stay vanes to maintain their original radial geometry and structural function without directly participating in flow correction.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If the pre-distributor structure is modified to correct the stay vane angles, then the flow incidence is corrected, but the implementation becomes difficult and expensive

Engineering Contradiction:

Improveflow incidence correctionVSAvoidimplementation difficulty and cost

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The invention simplifies manufacturing by segmenting the modification task: only the guide vanes require geometric modification, which can be done independently of the stay vanes. This avoids the need for complex, expensive operations on the pre-distributor structure as a whole, reducing both implementation difficulty and cost.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of modifying the stay vanes (the traditional approach), the invention inverts the approach by modifying the guide vanes to achieve the same flow correction effect. This reversal simplifies the manufacturing process since guide vanes are more accessible and easier to modify without compromising structural integrity.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentEP2811154B1Method of refurbishing an energy conversion facility and refurbished energy conversion facility

Publication Date: 2019.08.28 GE RENEWABLE TECH

Figure 1
Figure 2
Figure 3

AI summary

This method can be used for refurbishing a facility for converting hydraulic energy into electrical or mechanical energy, and vice versa, including a Francis type pump-turbine. The pump-turbine comprises a runner movable about an axis, a pre-distributor (204), including stay vanes defining between each pair of two adjacent stay vanes a first water passage channel (C1) and a distributor (206'), including guide vanes arranged downstream of the stay vanes in the direction of water flow feeding the pump-turbine operating in turbine mode, the guide vanes defining between each pair of two adjacent guide vanes a second water passage channel (C2). This method includes steps consisting in reducing the height, taken parallel to the axis of rotation of the runner, of the first water passage channels (C1) and reducing the height, taken parallel to the axis of rotation of the runner, of the second water passage channels (C2).