Bi-directional Fish Pass Helix with Open Center
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Solution Overview
Problem
Existing fish pass systems, such as Archimedes Screws, only allow for one-way fish passage, either upstream or downstream, whereas natural migrations often occur in both directions simultaneously, limiting the ability to convey fish in both directions within the same device.
Innovation Solution
A modular fish pass system with a helical blade and open central passage that allows fish to travel upstream and downstream simultaneously by maintaining water flow through the center, enabling two-way passage and accommodating varying headwater and tailwater elevations through adjustable end positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional Archimedes screw with center tube is used, then fish can be conveyed upstream or downstream in one direction, but the device cannot transport fish in both directions simultaneously
Solution Approach 1:
The fish pass system is divided into two separate passage channels: an inner passage for upstream-migrating fish and an outer passage for downstream-migrating fish. This segmentation allows each channel to be optimized for its specific direction of flow while operating simultaneously within the same device structure.
Solution Approach 2:
The inner passage is nested within the outer passage, creating a concentric dual-channel configuration. The inner passage containing the helical blade structure is positioned centrally within the outer passage, allowing both passages to occupy the same radial space while maintaining independent fish flow paths.
2Productivity
If fish are crowded into buckets between blades and center tube, then fish can be transported, but the system only allows one-way passage
Solution Approach 1:
The transport mechanism is segmented into two distinct systems: the inner passage uses traditional bucket-based transport for upstream fish, while the outer passage allows downstream fish to move freely with the water current, eliminating the need for mechanical buckets in one direction.
Solution Approach 2:
Instead of using mechanical buckets to force fish downstream, the system inverts the approach by allowing downstream-migrating fish to move naturally with the water flow in the outer passage, while reserving the mechanical bucket system exclusively for upstream transport in the inner passage.
3Ease of operation
If the helical blade rotates to convey fish, then fish passage is enabled, but varying headwater and tailwater elevations require adjustable end positions
Solution Approach 1:
The fish pass system incorporates adjustable end positions for both the inner and outer passages, allowing the structure to adapt dynamically to varying headwater and tailwater elevations. This dynamic adjustment capability enables the system to maintain proper operation across different water level conditions while preserving the rotational helical blade mechanism for fish conveyance.
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 system provides a safe and effective two-way passage for fish, aligning with natural migration patterns, by ensuring both ends of the pass system remain submerged to facilitate upstream and downstream migrations simultaneously, enhancing fish habitat connectivity across low-head barriers.
Implementation Method 1
Traditional Archimedes Screws have been successfully used as a 'fish pump' to move fish for decades
Data Source
AI summary
A fish pass system includes a helical blade having an outside diameter and an inside diameter extending between a first side of the helical blade and a second side of the helical blade. The inside diameter controls a flow of water flowing in a direction from the first side to the second side, and the inside diameter defines an open center of the fish pass system. Fish traveling in an opposite direction to the direction of the flow of the water pass through the fish pass system by riding in a space between helical blades as the helical blades are rotating, and fish traveling in the direction of the flow of the water pass through the open center of the fish pass system by swimming or moving over the inside diameter of the helical blades.