Lance Injector Thermal Expansion Constraint Mechanism
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Solution Overview
Problem
Lance injectors for gas turbines face issues with thermal expansion, leading to mechanical stresses and potential obstruction of fuel oil passages due to differing thermal expansions of components, affecting efficiency and emissions.
Innovation Solution
A lance injector design with a locking mechanism using a lock pin and end member to constrain axial slide between outer and inner tubular bodies, preventing relative movement and ensuring fluid passage integrity, combined with a guide bushing for centered positioning and fluid-tightness, allowing for thermal expansion without obstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the tubular bodies are allowed to expand freely due to thermal stress, then the components can accommodate thermal expansion, but mechanical stresses increase and may cause damage, loss of fitting, and malfunctioning
Solution Approach 1:
The patent changes the mechanical parameters of the tubular bodies by introducing a constraint mechanism that modifies their thermal expansion behavior. The constraint members (lock pins, end members, lock rings) change the expansion parameter from free expansion to constrained expansion, reducing mechanical stresses while maintaining reliability through controlled deformation.
2Reliability
If the tubular bodies are constrained to prevent relative axial slide, then mechanical stresses are reduced, but thermal expansion is restricted which may cause damage
Solution Approach 1:
The constraint mechanism is designed to be dynamic rather than completely rigid. The lock pins and end members provide axial constraint while the lock rings and guide bushings allow controlled radial and axial movement. This dynamic constraint system adapts to thermal expansion by allowing controlled movement while preventing excessive relative slide, thus managing thermal expansion without causing damage.
3Manufacturing precision
If the relative axial slide between tubular bodies is prevented in a locking region, then component positioning is maintained, but manufacturing complexity increases due to the locking mechanism
Solution Approach 1:
The locking mechanism is segmented into distinct functional components: lock pins for axial positioning, end members for constraint application, and lock rings for radial constraint. This segmentation allows each component to perform a specific function, simplifying the overall design and manufacturing of the complex locking system while maintaining precise component positioning.
4Stress or pressure
If cooling air is increased to manage thermal expansion, then thermal stresses are reduced, but energy consumption and cooling requirements increase
Solution Approach 1:
The patent replaces the thermal management approach (using cooling air flow to manage thermal stresses) with a mechanical constraint system. The lock pins, end members, and lock rings provide mechanical constraint that directly manages thermal expansion, substituting the need for high cooling air flow rates and reducing energy consumption while maintaining thermal stress reduction.
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 design significantly reduces mechanical stresses and malfunctions, maintaining component positioning and efficiency, and simplifies manufacturing by minimizing thermal expansion impacts, ensuring reliable fuel oil supply and reduced cooling air flow rates.
Implementation Method 1
The thermal stresses are considerable as a result of the very high temperatures in the combustion chamber (i.e. near the terminal and the nozzle). The consequent thermal expansions are not only remarkable, but also differ greatly from one component to the other
Implementation Method 2
The guide bushing (33) supports the inner tubular body (16) in centered position on axis A and allows the axial slide thereof
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A lance injector includes: an outer tubular body (15) and an inner tubular body (16), which extend along a common axis (A) and define a first fluid line (22) in a gap between the outer tubular body (15) and the inner tubular body (16), and a second fluid line (23) in the inner tubular body (16); a nozzle (18) connected fluidically to the first fluid line (22) and the second fluid line (23), at respective first ends (15a, 16a) of the outer (15) and inner (16) tubular bodies; and constraint members (17, 27, 30) configured so as to prevent the relative axial slide between the outer tubular body (15) and the inner tubular body (16) in a locking region at the respective first ends (15a, 16a), and such to permit the relative axial slide between the outer tubular body (15) and the inner tubular body (16) as effect of expansion elsewhere.