Coiled Fuel Injector Conduit With Thickened Bends for Thermal Stress
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Solution Overview
Problem
Conventional fuel injectors for gas turbine engines face significant thermal stresses due to the temperature difference between the cold fuel and hot combustion products, leading to potential fractures and increased complexity, cost, and maintenance needs, particularly at locations of curvature in coiled fuel conduits.
Innovation Solution
The fuel conduit design includes thickened wall thickness at the minimum radius of curvature locations along both the longitudinal and coil segments, coupled with adapters, to reduce stress and enhance flexibility, allowing the coiled tube to accommodate thermal expansion while maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fuel conduits with uniform wall thickness are used in coiled configurations, then manufacturing is simpler, but stress concentration at minimum radius of curvature locations leads to fractures and reduced reliability
Solution Approach 1:
The fuel conduit incorporates variable wall thickness with localized thickening at minimum radius of curvature locations. This non-uniform thickness distribution provides enhanced stress resistance precisely where needed in the coiled configuration, while maintaining simpler geometry elsewhere, thereby improving reliability without excessive manufacturing complexity
Solution Approach 2:
The invention changes the geometric parameter of wall thickness from uniform to variable along the conduit length. By adjusting the thickness parameter specifically at critical locations (minimum radius of curvature), the conduit achieves better stress distribution and fracture resistance while accommodating thermal expansion requirements
2Reliability
If stress relief devices are added to accommodate thermal gradients, then thermal stress management improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The fuel conduit itself is designed to accommodate thermal expansion through its variable wall thickness geometry and coiled configuration. The conduit structure provides its own stress relief capability without requiring separate stress relief devices, thereby maintaining thermal stress resistance while reducing overall device complexity
Solution Approach 2:
The coiled configuration with controlled curvature radii and variable wall thickness allows the conduit to flex and accommodate thermal expansion inherently. The curved geometry with thickened walls at critical points provides both the flexibility needed for thermal movement and the structural strength to resist stress, eliminating the need for additional stress relief components
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 increases the service life of fuel injectors by reducing stress and fatigue-related fractures, improving reliability and reducing the complexity and cost associated with stress relief devices, while maintaining flexibility to accommodate thermal gradients.
Implementation Method 1
the coiled tube to accommodate thermal expansion and contraction
Implementation Method 2
accommodate thermal gradients during operation
Implementation Method 3
thickened wall thickness at the minimum radius of curvature locations along both the longitudinal and coil segments, coupled with adapters, to reduce stress and enhance flexibility
Implementation Method 4
reducing stress and fatigue-related fractures
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A fuel conduit (110) for a fuel injector includes a coiled tube (126) with a longitudinal segment (118) arranged along a flow axis and a radial segment (120). The radial segment extends about the flow axis and is in fluid communication with the longitudinal segment. The wall one or more of the longitudinal and radial segments increases at a thickness transition location offset from a minimum radius of curvature location along the fuel conduit to limit stress within the fuel conduit. Fuel injectors and methods of making fuel injectors are also described.