Hydrostatic Seal Carrier Arm for Thermal Growth and Leakage Control
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Solution Overview
Problem
Gas turbine engines face challenges in maintaining efficient seals between rotating and static components due to thermal stresses and leakage issues, particularly in maintaining a consistent gap under varying operating conditions.
Innovation Solution
A hydrostatic seal assembly with a seal carrier featuring a radial outer wall, axial wall, and carrier arm, which is secured to a static structure via a carrier flange, allowing for radial movement and flexibility to accommodate thermal growth differences between components, thus maintaining a selected gap and reducing leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a hydrostatic seal is used to maintain a selected gap between rotating and static components, then leakage is reduced, but thermal stresses increase during transient operating conditions due to thermal expansion
Solution Approach 1:
The seal carrier is divided into multiple functional segments: a radial outer wall for structural support, an axial wall for positioning, and a carrier arm for flexibility. This segmentation allows each part to perform its specific function while accommodating thermal expansion differently, reducing overall thermal stress on the seal assembly
Solution Approach 2:
The carrier arm is designed as a flexible element that can bend and deform to accommodate differential thermal expansion between the rotating and static components. This flexibility allows the seal to maintain its gap and sealing function while absorbing thermal stresses that would otherwise be transmitted to the seal components
2Manufacturing precision
If a rigid seal carrier is used to maintain precise gap positioning, then manufacturing precision is improved, but adaptability to thermal growth differences deteriorates
Solution Approach 1:
The seal carrier transitions from a completely rigid structure to a dynamic structure where the carrier arm can flex and adapt its position. This dynamic capability allows the carrier to maintain precise gap positioning under normal conditions while adapting to thermal growth differences during transient operating conditions
Solution Approach 2:
By segmenting the carrier into rigid portions (radial outer wall, axial wall) and a flexible portion (carrier arm), the design achieves both manufacturing precision for gap positioning and adaptability for thermal growth accommodation through the flexible segment
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 hydrostatic seal assembly effectively reduces thermal stresses and leakage by allowing for flexible accommodation of thermal growth, enhancing the operational efficiency and reliability of gas turbine engines.
Implementation Method 1
a shoe having radial travel in response to a pressure differential across the seal
Implementation Method 2
Depending on thermal properties and hardware configuration of the gas turbine engine, the hydrostatic seal may be subject to high stresses during transient operating conditions as components thermally expand into one another
Data Source
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AI summary
A hydrostatic seal assembly includes a primary seal (68) assembly configured to maintain a selected gap (76) between the primary seal (68) and a rotating component (64), and a seal carrier (66). The seal carrier (66) includes a radial outer wall (110), an axial wall (88) extending from the radial outer wall (110) at a first axial end of the radial outer wall (110), and a carrier arm (112) extending from the radial outer wall (110) at a second axial end of the radial outer wall (110) opposite the first axial end. The carrier arm (112) is secured to a static structure (62) for sealing between the rotating component (64) and the static structure (62).