Gas Turbine Fuel Nozzle Bonding for Fatigue-Resistant Joints
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Solution Overview
Problem
The multi-hole coaxial jet burner structure in gas turbine combustors faces challenges in forming reliable bonded portions between fuel nozzles and base plates due to high-cycle fatigue and thermal stress, leading to insufficient strength and durability.
Innovation Solution
The fuel nozzle is metallurgically and integrally bonded to a base plate using a fusion joint or brazing joint on the surface and pressure bonding on the inside, enhancing the mechanical strength and reliability through electron beam welding and hot isostatic pressing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional bonding methods (screwing or simple welding) are used to attach fuel nozzles to the base plate, then the manufacturing process is simple, but the bond portion reliability is insufficient due to high-cycle fatigue and thermal stress
Solution Approach 1:
The bonding interface is divided into two distinct zones: a surface portion subjected to fusion joint or brazing for strong bonding, and an inside portion subjected to pressure bonding for intimate contact and stress distribution. This segmentation allows each zone to address specific requirements, resolving the contradiction between reliability and process simplicity.
Solution Approach 2:
The bonding process utilizes parameter changes by applying different bonding mechanisms to different portions of the interface. The surface portion uses thermal parameters (fusion/brazing temperature) while the inside portion uses pressure parameters (isostatic pressing), creating a composite bonding structure that achieves high reliability.
2Productivity
If fuel nozzles are disposed at small intervals in multi-hole coaxial jet burners, then the combustor efficiency is improved, but forming sufficient welded portions becomes difficult
Solution Approach 1:
The bonding approach transitions from a single-plane welding problem to a three-dimensional solution by using isostatic pressing that applies pressure from all directions. This allows sufficient bonded portion formation even when nozzles are closely spaced, as the pressure bonding penetrates and consolidates the interface volume rather than relying solely on surface welding.
Solution Approach 2:
The invention merges two bonding methodologies (fusion joint/brazing and pressure bonding) into a single integrated bonding process. This combination allows the surface fusion to provide strong initial bonding while the subsequent pressure bonding ensures complete interface consolidation, solving the manufacturing precision issue for closely-spaced nozzles.
3Duration of action of stationary object
If the fuel nozzle and base plate are subjected to high-cycle fatigue and thermal stress during long-term operation, then the operational duration is extended, but the conventional bond portions fail due to insufficient strength
Solution Approach 1:
The dual-zone bonding structure acts as a cushioning mechanism against thermal stress and fatigue. The pressure-bonded inside portion provides intimate contact that distributes thermal stresses, while the fusion-bonded surface portion provides strong anchorage, together preventing bond failure during long-term operation.
Solution Approach 2:
The bond portion becomes a composite structure with two distinct bonding mechanisms: a fusion-bonded surface layer and a pressure-bonded interior region. This composite bonding approach combines the advantages of both methods, creating a bond portion with superior strength and fatigue resistance for extended operational duration.
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 solution significantly improves the mechanical strength and reliability of the fuel nozzle, enabling extended operation of gas turbine combustors with reduced risk of backfire and NOx emissions.
Implementation Method 1
An interface between the fuel nozzle and the base plate includes a surface in which bonding is performed by a fusion joint
Implementation Method 2
bonding is performed by a fusion joint or a brazing joint
Implementation Method 3
an inside part in which bonding is performed by pressure bonding
Implementation Method 4
enhancing the mechanical strength and reliability through electron beam welding
Implementation Method 5
enhancing the mechanical strength and reliability through electron beam welding and hot isostatic pressing processes
Data Source
AI summary
[Problem]To provide a fuel nozzle for a gas turbine combustor, offering favorable durability and strength reliability.[Solving Means]A method for manufacturing a fuel nozzle for a gas turbine combustor, the method comprising: (a) fitting a fuel nozzle having an internal through hole into a through hole or a recess provided in a base plate; (b) bonding, by a fusion joint or a brazing joint, the fuel nozzle to the base plate in an interface therebetween on a surface of the base plate; and (c) following the step of (b), subjecting the fuel nozzle and the base plate to a pressure bonding process to thereby pressure bond the fuel nozzle and the base plate in the interface therebetween.