Differential Thermal Expansion Engine Clearance Control
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Solution Overview
Problem
Gas turbine engines face performance and reliability issues due to varying clearances between rotating and static components, which are affected by thermal growth and operational loads, leading to inefficiencies or wear, as the clearance is not effectively controlled across different engine states.
Innovation Solution
A clearance control thermal ring system is introduced, comprising a flange, bolt, and nut assembly with a slotted hole, where the thermal ring and seal ring interact to manage thermal growth, maintaining a tailored clearance profile by limiting excessive growth of the seal ring, using nickel-based alloys with different thermal expansion coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the clearance between blade tip and engine case is made small to improve performance, then output efficiency is improved, but the blade tip may rub against the engine case causing wear
Solution Approach 1:
The patent changes the thermal expansion parameters of different components by selecting materials with different coefficients of thermal expansion. The seal ring is made of a material with a higher coefficient of thermal expansion than the engine case, allowing the seal ring to expand more with temperature increases, thereby maintaining optimal clearance under various thermal loading conditions while preventing blade tip rubbing
Solution Approach 2:
The patent employs composite material selection where the seal ring is constructed from a nickel-based superalloy (such as Inconel 713 or Inconel 738) that exhibits superior high-temperature strength and controlled thermal expansion characteristics, while the engine case uses a different alloy composition. This composite material approach enables differential thermal growth that maintains reliable clearance
2Reliability
If the clearance between blade tip and engine case is increased to prevent wear, then component reliability is improved, but output performance and efficiency are reduced
Solution Approach 1:
The patent dynamically adjusts the effective clearance parameter through thermal expansion differences. As the engine operates and temperature increases, the seal ring expands radially outward due to its higher coefficient of thermal expansion, automatically reducing the clearance to optimal levels for high efficiency operation while still preventing blade tip contact through controlled expansion
3Stability of the object's composition
If materials with high thermal resistance are used to reduce thermal growth, then clearance stability is improved, but the component may experience excessive thermal stress
Solution Approach 1:
The patent employs nickel-based superalloys (such as Inconel 713 or Inconel 738) for the seal ring that provide an optimal balance between thermal expansion characteristics and mechanical strength. These alloys maintain structural integrity and resist thermal stress while exhibiting the desired thermal expansion behavior to stabilize clearance under varying thermal conditions
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 system maintains a target tolerance in clearance between rotating and stationary hardware, balancing wear prevention and performance by controlling thermal growth, thus optimizing engine efficiency and reliability across various operational conditions.
Implementation Method 1
The clearance control thermal ring (220) may be made of a material that has a coefficient of thermal expansion that is less than a coefficient of thermal expansion associated with the aft seal ring (216). The clearance control thermal ring (220) may control thermal growth of the aft seal ring (216).
Data Source
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AI summary
Aspects of the disclosure are directed to a system (200) of an engine, comprising: a clearance control thermal ring (220), and a seal ring (216), where a radial gap (240) with respect to an axial centerline of the engine is formed between a radial end of the clearance control thermal ring (220) and a facing radial surface of the seal ring (216), where the clearance control thermal ring (220) is made of a first material and the seal ring (216) is made of a second material that is different from the first material, and where a first coefficient of thermal expansion of the first material is less than a second coefficient of thermal expansion of the second material.