Non-Circular Pipe Bend to Resist Bourdon Effect Movement
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Solution Overview
Problem
Conventional fluid pipes with bends in aerospace applications face challenges due to the Bourdon effect, where internal pressures cause undesirable movement, leading to complex compliance systems and increased size, weight, and cost, especially when trying to avoid other structures like wing structures in aircraft.
Innovation Solution
The use of a pipe with a non-circular cross-section bend portion, such as an ellipse, that aligns its longest axis with the direction of the bend to resist relative movement and counteract the Bourdon effect, thereby reducing stress and simplifying support and sealing requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional straight pipes with angled connectors are used to achieve bends, then the pipe can transfer fluid along bent paths, but the arrangement becomes complex with multiple connectors, supports and seals, increasing cost, size and weight
Solution Approach 1:
The patent merges multiple separate components (straight pipe sections and angled connectors) into a single integral bent pipe structure. The bend portion is formed as one continuous piece with the straight portions, eliminating the need for separate connectors, supports and seals that would be required in conventional assemblies.
Solution Approach 2:
The pipe is divided into distinct functional portions (first straight portion, bend portion, second straight portion) with the bend portion having a specific non-circular cross-section designed to resist Bourdon effect, allowing each portion to be optimized for its specific function while maintaining overall simplicity.
2Device complexity
If pipes with integral bends are used to mitigate complexity, then the arrangement of connectors and supports is simplified, but internal pressures cause the bend to open out and the pipe to straighten due to the Bourdon effect, necessitating complex compliance systems
Solution Approach 1:
The bend portion is given a non-circular cross-section (asymmetric shape) rather than a conventional circular cross-section. This asymmetric geometry creates uneven pressure distribution on the inner and outer radii of the bend that counteracts the Bourdon effect, preventing the bend from opening out under internal pressure without requiring complex compliance systems.
Solution Approach 2:
The patent changes the geometric parameter of the cross-section from circular to non-circular, which fundamentally alters the pressure distribution characteristics and the mechanical response of the bend to internal pressure, thereby eliminating the Bourdon effect.
3Stability of the object's composition
If complex compliance systems are added to seal and support the pipe whilst tolerating pipe movement, then the pipe can accommodate Bourdon effect movement, but the benefits of using integral bends are negated and size and weight increase
Solution Approach 1:
The patent converts the harmful Bourdon effect (which causes unwanted pipe movement) into a beneficial self-balancing mechanism. The non-circular cross-section is designed so that the pressure distribution that would normally cause the bend to open out instead creates restoring forces that maintain the bend configuration, eliminating the need for compliance systems.
4Ease of manufacture
If conventional circular cross-section pipes are used, then the pipe is easy to manufacture, but the different surface areas of the intrados and extrados produce unbalanced forces that encourage the bend to open out
Solution Approach 1:
The patent deliberately introduces asymmetry in the cross-sectional shape to create a balanced force distribution. The non-circular cross-section is designed so that the larger surface area on one side compensates for the smaller surface area on the other, creating equal and opposite forces that balance each other out under internal pressure.
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
This design mitigates pipe movement and associated stresses, allowing for smaller, lighter structures while maintaining performance, and simplifies fluid connection requirements by reducing the need for complex compliance systems and larger connectors.
Implementation Method 1
when pipes with bends are subject to internal pressures (e.g. when transporting fluids), the different surface areas of the intrados and extrados of the bend (i.e. the radially-inner and radially-outer portions of the bend) can produce a net force which encourages the bend to open out and the pipe to straighten. This is known as the Bourdon effect.
Data Source
AI summary
A pipe is provided which extends from a first portion to a second portion. The pipe is arranged to transfer fluid at an operational pressure from the first portion to the second portion. The pipe comprises a bend portion between the first and second portions in which the pipe transitions from extending in a first direction A to extending in a second direction B. The bend portion of the pipe comprises a non-circular cross section, the non-circular cross section having a shape selected to resist relative movement of the first and second portions when the pipe is subject to the operational pressure.