Gas Turbine Combustor Intermediate Duct Thermal Expansion
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Solution Overview
Problem
Conventional gas turbine engines face challenges in efficiently managing thermal expansion and maintaining optimal combustion conditions due to the lack of effective intermediate ducts between the liner and transition ducts, leading to potential binding and stress issues during operation.
Innovation Solution
The introduction of an intermediate duct with a friction fit coupling mechanism between the liner and transition duct, along with a secondary fuel injection system, which injects fuel downstream to reduce NOx production and accommodate thermal expansion, thereby allowing unconstrained axial movement and improving combustion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If an intermediate duct is rigidly connected between the liner and transition duct, then structural stability is improved, but thermal expansion causes binding and stress issues
Solution Approach 1:
The intermediate duct is designed with movable connections (friction fit couplings) at both its inlet and outlet portions, allowing it to dynamically adjust its position in response to thermal expansion while maintaining structural integrity. This dynamic capability resolves the contradiction by enabling the duct to remain stable under normal conditions while accommodating dimensional changes during operation.
Solution Approach 2:
The friction fit coupling mechanism allows the intermediate duct to change its axial position parameter in response to temperature changes. The coupling provides sufficient friction to maintain structural stability during operation while allowing controlled movement when thermal expansion occurs, thus resolving the contradiction between stability and thermal stress.
2Stress or pressure
If a friction fit coupling is used to accommodate thermal expansion, then thermal stress is reduced, but structural stability may be compromised
Solution Approach 1:
The friction fit coupling mechanism allows the intermediate duct to change its axial position parameter in response to temperature changes. The coupling provides sufficient friction to maintain structural stability during operation while allowing controlled movement when thermal expansion occurs, thus resolving the contradiction between stability and thermal stress.
Solution Approach 2:
The intermediate duct is designed with movable connections (friction fit couplings) at both its inlet and outlet portions, allowing it to dynamically adjust its position in response to thermal expansion while maintaining structural integrity. This dynamic capability resolves the contradiction by enabling the duct to remain stable under normal conditions while accommodating dimensional changes during operation.
3Productivity
If fuel is injected only in the liner, then combustion efficiency is achieved, but NOx production increases
Solution Approach 1:
The fuel injection system is segmented into two distinct zones: the liner and the intermediate duct. This segmentation allows different portions of fuel to be injected at different locations, enabling efficient combustion in the liner while reducing NOx formation through secondary fuel injection in the intermediate duct where temperatures are more favorable.
Solution Approach 2:
The intermediate duct serves as an intermediary combustion chamber between the liner and transition duct. By injecting fuel into this intermediate zone, the system achieves a two-stage combustion process that maintains efficiency while controlling NOx production through the cooler conditions in the intermediate duct.
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 configuration enhances combustion efficiency by reducing NOx production and accommodating thermal expansion, preventing binding and stress issues, and optimizing the flow of working gases, leading to improved engine performance.
Implementation Method 1
accommodating thermal expansion, preventing binding and stress issues
Implementation Method 2
provides fuel which is adapted to be mixed with at least a portion of the pressurized air and ignited in the liner inner volume creating combustion products
Data Source
AI summary
A combustor assembly in a gas turbine engine. The combustor assembly includes a combustor device coupled to a main engine casing, a first fuel injection system, a transition duct, and an intermediate duct. The combustor device includes a flow sleeve for receiving pressurized air and a liner disposed radially inwardly from the flow sleeve. The first fuel injection system provides fuel that is ignited with the pressurized air creating first working gases. The intermediate duct is disposed between the liner and the transition duct and defines a path for the first working gases to flow from the liner to the transition duct. An intermediate duct inlet portion is associated with a liner outlet and allows movement between the intermediate duct and the liner. An intermediate duct outlet portion is associated with a transition duct inlet section and allows movement between the intermediate duct and the transition duct.