Multi-staged Cowl for Hydrokinetic Turbines
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Solution Overview
Problem
Existing draft tubes for hydrokinetic turbines are not dimensioned to be submerged in shallow bodies of water, such as rivers, leading to inefficiencies in water flow and pressure drop at the runner cross-section, which limits the power output.
Innovation Solution
A multi-staged cowl design with varying widths and heights along the water flow direction, including inlet, intermediate, and outlet draft tubes, and water passages between them, to maintain stable and increased water flow and pressure drop while minimizing cavitation and vortices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the overall height of draft tube assemblies is reduced to fit shallow bodies of water, then the turbine can be deployed in rivers and shallow environments, but the water flow and pressure drop at the runner cross-section become insufficient
Solution Approach 1:
The draft tube assembly is divided into multiple stages (first stage, second stage, third stage) with each stage having specific width and height characteristics. This segmentation allows the overall height to be reduced while maintaining functional performance through optimized multi-level configuration.
Solution Approach 2:
The patent transitions from a single-stage vertical configuration to a multi-stage configuration that utilizes both vertical and horizontal dimensions. The stages have varying widths and heights, creating a three-dimensional optimized flow path that maintains pressure drop and water flow performance while reducing overall height.
2Length of stationary object
If the overall height of draft tube assemblies is reduced to fit shallow bodies of water, then the turbine can be deployed in rivers and shallow environments, but the power output is limited
Solution Approach 1:
The multi-stage segmentation creates optimized flow paths at each stage that maintain pressure drop across the runner, ensuring sufficient power generation capability despite reduced overall height.
Solution Approach 2:
The patent optimizes geometric parameters (width, height, length) of each stage independently. The first stage has width W1 and height H1, the second stage has width W2 and height H2, and the third stage has width W3 and height H3, with specific relationships between these parameters that maximize power output within constrained height.
3Device complexity
If conventional draft tube designs are used in shallow water, then the structure is simple, but fluid separation and vortices occur reducing efficiency
Solution Approach 1:
The multi-stage configuration with intermediate flow passages between stages prevents fluid separation and vortex formation by creating controlled flow paths. Each stage transitions smoothly to the next, maintaining laminar flow and preventing turbulence that would reduce efficiency.
Solution Approach 2:
The intermediate flow passages act as mediators between stages, allowing controlled water flow that prevents direct abrupt transitions. These passages eliminate fluid separation and vortex formation by providing smooth flow path transitions.
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 multi-staged cowl design enhances water flow and pressure drop at the runner cross-section, maximizing power output while maintaining operational viability in shallow water environments by preventing fluid separation and vortices, and minimizing cavitation.
Implementation Method 1
water can flow through the turbine, from a section upstream from the runner cross section towards a section downstream from the runner cross-section
Implementation Method 2
increase the water flow and the pressure drop at the runner cross-section of the turbine
Implementation Method 3
minimizing cavitation and vortices
Data Source
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AI summary
The multi-staged cowl described herein allows to increase and maximize water mass flow and pressure drop at the runner cross-section of a hydrokinetic turbine so as to maximize produced power output, while respecting dimensional constraints provided by a shallow body of water, a river for example, in which the hydrokinetic turbine can be submerged. The multi-staged cowl described herein can thus be configured so as to allow water to flow through the hydrokinetic turbine at a substantially stable water mass flow, eliminating instability, avoiding vortices, minimizing cavitation and avoiding fluid separation to negligible levels, and can include an inlet, an outlet and multiple stages which can extend between the inlet and the outlet, so that water can flow therethrough in a water flow direction.