Flexible Ventilation Duct Layout for Oval Shape Retention
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Solution Overview
Problem
Conventional flexible ventilation ducts in underground mines and tunnels tend to adopt a circular cross-sectional shape under high pressure air flow, which is undesirable as it does not conform well to the ceiling and entry widths, potentially interfering with vehicles and machinery.
Innovation Solution
The duct maintains an oval cross-sectional shape by attaching opposing internal sides with limited movement, using connectors and fastening devices to restrict expansion, ensuring it hugs the ceiling while accommodating high air flow rates without restriction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flexible duct material is used to conform to ceiling undulations and accommodate machinery passage, then the duct can easily adapt to mine geometry and vehicle passage, but the duct tends to expand into a circular shape under high pressure air flow
Solution Approach 1:
The duct is segmented into multiple sections with connectors between them. Each section can independently maintain its oval shape while the entire duct system remains flexible enough to accommodate ceiling undulations and machinery passage.
Solution Approach 2:
Ribs are pre-formed into the duct material during manufacturing, creating internal structural support that maintains the oval cross-sectional shape before the duct is even installed. This preliminary structural preparation prevents circular expansion under pressure.
2Shape
If the duct is made rigid to maintain a rectangular or oval shape, then the cross-sectional shape is preserved under pressure, but the duct cannot easily conform to ceiling undulations or accommodate machinery passage
Solution Approach 1:
The duct has non-uniform local properties: rigid ribs in specific locations maintain the oval shape, while the flexible fabric material in other areas allows the duct to bend and conform to ceiling geometry. This local differentiation of stiffness enables both shape maintenance and adaptability.
Solution Approach 2:
The duct combines rigid structural elements (ribs formed from rigid or semi-rigid material) with flexible fabric material to create a composite structure that exhibits both rigidity for shape maintenance and flexibility for adaptation to ceiling geometry.
3Productivity
If the duct expands under high pressure to increase airflow capacity, then more air can be carried, but the duct height increases and interferes with vehicles and machinery
Solution Approach 1:
The duct maintains an oval cross-sectional shape rather than expanding into a circle under pressure. The curved rib structure guides the expansion along the longitudinal axis while maintaining the oval geometry, allowing increased airflow capacity without excessive height increase that would interfere with machinery.
Data Source
AI summary
A ventilation ducting arrangement includes a flexible conduit having an inner surface defining a channel carrying a flow of air. First connectors are aligned in a length direction along a length of the inner surface of the conduit. Second connectors are aligned along the length direction. Each of the second connectors has a position along the length direction that is the same as a position of a corresponding first connector along the length direction but that is diametrically opposed to the position of the corresponding first connector relative to a circumference of the inner surface. Each of a plurality of fastening devices interconnects a respective one of the first connectors and a respective one of the second connectors such that a distance between the interconnected first connector and the interconnected second connector is limited by a length of the fastening device.