Horizontal Cable Screen for Fish Protection
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Solution Overview
Problem
Existing fish protection systems at hydroelectric installations, such as gratings, face challenges in balancing fish protection with high hydraulic losses and maintenance costs, particularly when small grating spacings are required for effective fish deterrence.
Innovation Solution
A fish protection cable screen using cables braced parallel and horizontally below the water surface between abutments, allowing for large span widths and low vertical spacing to deter fish, with optional features like vibration and integrated light elements to enhance deterrence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If small grating spacings are used to prevent fish from entering turbine inlets, then fish protection is improved, but hydraulic losses and maintenance costs increase
Solution Approach 1:
The grating structure is segmented into multiple horizontal cable screens with varying vertical spacings. The first cable screen has smaller spacings (2-10 cm) for effective fish protection, while subsequent screens have progressively larger spacings (10-50 cm, 50-100 cm). This segmentation allows the critical fish protection function to be achieved with minimal hydraulic resistance, as fish are stopped by the first screen while water flows freely through the larger gaps in subsequent screens.
Solution Approach 2:
The invention transitions from traditional vertical grating bars to horizontal cable screens arranged in multiple vertical layers. This dimensional reconfiguration allows the system to achieve fish protection through cumulative vertical spacing rather than relying solely on small horizontal gaps, thereby reducing hydraulic losses while maintaining effectiveness.
2Reliability
If small grating spacings are used to prevent fish from entering turbine inlets, then fish protection is improved, but maintenance costs increase
Solution Approach 1:
The grating structure is segmented into multiple horizontal cable screens with varying vertical spacings. The first cable screen has smaller spacings (2-10 cm) for effective fish protection, while subsequent screens have progressively larger spacings (10-50 cm, 50-100 cm). This segmentation allows the critical fish protection function to be achieved with minimal hydraulic resistance, as fish are stopped by the first screen while water flows freely through the larger gaps in subsequent screens.
Solution Approach 2:
The invention varies the vertical spacing parameter across different cable screens, with the first screen having small spacings (2-10 cm) for fish protection and subsequent screens having progressively larger spacings. This parameter change optimizes the balance between fish protection effectiveness and hydraulic efficiency, reducing maintenance requirements.
3Ease of operation
If traditional vertical gratings are used, then installation is simple, but fish protection effectiveness is reduced due to fish body shape
Solution Approach 1:
The invention inverts the traditional vertical orientation of grating bars and uses horizontal cable screens instead. This inversion exploits the typical body shape of fish, which makes it difficult for them to swim through horizontal barriers, thereby significantly improving fish protection effectiveness while maintaining installation simplicity.
4Device complexity
If large span widths are used in cable screens, then structural complexity is reduced, but fish protection effectiveness may be compromised
Solution Approach 1:
The cable screen system is segmented into multiple horizontal layers with varying spacings. The first cable screen uses relatively small span widths (2-10 cm vertical spacing) to ensure effective fish protection, while subsequent screens use progressively larger span widths. This segmentation allows large overall span widths to be achieved without compromising fish protection, as the first screen maintains the critical protection function.
Solution Approach 2:
The invention addresses the span width challenge by adding a vertical dimension with multiple cable screens at different heights. This allows the system to achieve large horizontal span widths while maintaining effective fish protection through the cumulative effect of multiple vertical layers with appropriate spacings.
Data Source
AI summary
An apparatus for holding back, and diverting, fish in bodies of water by the arrangement of parallel cables (S) braced between two or more abutments (W), wherein the distance between the cables is small enough to prevent fish from swimming through the apparatus.