Labyrinth Seal Eccentric Gaps for Thermal Management
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Solution Overview
Problem
Labyrinth seal systems in gas turbine engines face challenges in withstanding high thermal loads, leading to potential damage and inefficiency due to intense thermal loading on sealing fins.
Innovation Solution
The design incorporates axially arranged sealing fins on a rotor with a radially facing run-in element, featuring eccentrically offset sealing gaps to create targeted passages for air flow, enabling convective cooling and enhancing thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional labyrinth seals with uniform sealing gaps are used, then the sealing function is provided, but the thermal loading on sealing fins becomes excessive
Solution Approach 1:
The patent applies local quality by creating non-uniform sealing gaps with specific maxima and minima distributed around the circumference. The maxima (larger gaps) are positioned to allow cooling air flow, while minima (smaller gaps) maintain sealing effectiveness. This local variation in gap size enables different regions of the sealing fin to experience different thermal conditions, with cooling air specifically targeting high-temperature zones.
Solution Approach 2:
The patent utilizes pneumatic principles by introducing cooling air flow through the strategically positioned maxima of the sealing gaps. The pressure differential and fluid dynamics of the cooling air are harnessed to convectively cool the sealing fins, transforming the sealing gap structure into a dual-function element that both seals and provides thermal management.
2Ease of manufacture
If sealing gap heights are uniformly distributed, then manufacturing is simplified, but convective cooling passages cannot be formed
Solution Approach 1:
The patent implements asymmetry by deliberately designing non-uniform sealing gap heights around the circumference of the sealing fin. The gaps vary between maxima and minima at specific angular positions, breaking the symmetry that would otherwise be present in conventional uniform seals. This asymmetric distribution is specifically engineered to create flow passages while maintaining adequate sealing clearance in other regions.
Solution Approach 2:
The patent applies local quality by creating non-uniform sealing gaps with specific maxima and minima distributed around the circumference. The maxima (larger gaps) are positioned to allow cooling air flow, while minima (smaller gaps) maintain sealing effectiveness. This local variation in gap size enables different regions of the sealing fin to experience different thermal conditions, with cooling air specifically targeting high-temperature zones.
3Temperature
If cooling air flow passages are created through non-uniform sealing gaps, then thermal loading is reduced, but sealing effectiveness may be compromised
Solution Approach 1:
The patent applies local quality by creating non-uniform sealing gaps with specific maxima and minima distributed around the circumference. The maxima (larger gaps) are positioned to allow cooling air flow, while minima (smaller gaps) maintain sealing effectiveness. This local variation in gap size enables different regions of the sealing fin to experience different thermal conditions, with cooling air specifically targeting high-temperature zones.
Solution Approach 2:
The patent applies partial action by providing cooling air flow only at specific locations (maxima of sealing gaps) rather than uniformly across the entire sealing circumference. This partial cooling approach is sufficient to reduce thermal loading on the sealing fin while maintaining adequate sealing clearance in the minima regions, avoiding the need for excessive cooling that would require larger gaps throughout and compromise sealing effectiveness.
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 effectively reduces thermal loading on sealing fins by allowing targeted air flow cooling, thereby improving the labyrinth seal system's ability to withstand high thermal loads and maintain efficiency.
Implementation Method 1
By means of the targeted variation of the sealing gap heights along the circumferential direction, it can be achieved that an air flow flows in targeted fashion along the labyrinth seal, which air flow permits convective cooling.
Data Source
AI summary
A labyrinth seal system having at least two sealing fins arranged axially one behind the other on a rotor of a turbomachine and having a radially facing run-in element for the at least two sealing fins on a stator of the turbomachine, wherein in each case one radial sealing gap exists between the run-in element and the at least two sealing fins, wherein maxima of the radial sealing gaps are arranged offset with respect to one another in a circumferential direction, such that, in the region of the maxima, a passage exists in targeted fashion, for an air flow to the sealing fins that follow downstream, in the event of rubbing against the stator. This may be applied for example in a gas turbine engine.