Pelton Turbine Spiral Casing Fins for Secondary Flow Control
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Solution Overview
Problem
In hydraulic machine distribution assemblies, secondary flows in curved conduits reduce the kinetic energy of water jets acting on Pelton turbine wheels, leading to inefficiencies due to non-cylindrical jet shapes and deviations.
Innovation Solution
A distribution assembly with fins attached to the inner wall of the curved conduit, featuring openings that dissipate secondary flows, optimizing the kinetic energy of water jets by reducing their velocity and maintaining jet alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional curved conduits are used without fins, then the structure is simple, but secondary flows reduce kinetic energy and jet alignment
Solution Approach 1:
The curved conduit is segmented by adding multiple fins with openings that divide the flow path. These fins create multiple smaller flow channels that control and direct the water flow, reducing secondary flows while maintaining manageable structural complexity through modular fin elements.
Solution Approach 2:
The fins incorporate openings that allow controlled passage of water while maintaining structural integrity. This porous approach enables the fins to dissipate secondary flows effectively while still guiding the main flow direction, improving kinetic energy without requiring solid blocking structures.
2Productivity
If fins without openings are used, then secondary flows are blocked, but flow dispersion increases and kinetic energy is reduced
Solution Approach 1:
The fins are designed with openings that allow selective passage of water. This porous structure enables the fins to reduce secondary flow velocities by creating turbulence and dissipation zones, while simultaneously allowing the main flow to pass through with minimal dispersion, thus preserving kinetic energy.
Solution Approach 2:
The fins with openings act as intermediary elements between the primary flow and secondary flows. They mediate the interaction by allowing controlled exchange between main flow and secondary currents, dissipating harmful secondary flows while maintaining the integrity and kinetic energy of the primary water jet.
3Object-generated harmful factors
If larger fins are used to reduce secondary flows, then secondary flow velocity decreases, but the conduit cross-section is reduced
Solution Approach 1:
Instead of using a single large fin that would block significant cross-section, multiple smaller fins are distributed across the conduit. Each fin is sized to effectively reduce secondary flows locally, while the distributed arrangement maintains adequate open cross-sectional area for primary flow passage.
Solution Approach 2:
The fins incorporate openings that reduce their effective blocking area while maintaining their flow-control function. This allows the fins to be sufficiently large to reduce secondary flows effectively, without permanently reducing the available cross-section for main water flow to an unacceptable degree.
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 solution effectively reduces secondary flow velocities and maintains jet alignment, enhancing the efficiency of the Pelton turbine by maximizing kinetic energy and minimizing deviations.
Implementation Method 1
When water flows in a curved conduit, it is subjected to centrifugal accelerations. In particular, in a curved conduit belonging to a distribution assembly intended to supply water to a Pelton turbine wheel, the water follows curved paths, along which it is subjected to centrifugal accelerations.
Implementation Method 2
The pressure gradients generated in the central zone of the curved duct C induce a circumferential circulation of water along the walls, between the internal wall INT and the external wall EXT.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The invention relates to a curved conduit (2) pertaining to a hydraulic machine, for channeling a flow. Said curved conduit (2) is provided with fins (8) that are fixed to its inner wall (22) and comprise openings.