Rolling-Element Seal Assembly for Gas Turbine Leakage Control
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Solution Overview
Problem
Existing gas turbine engines face challenges in controlling compressed air or combustion gas leakage through radial gaps between rotor shafts and stator vanes, leading to wear and reduced efficiency due to friction and the need for leakage airflow.
Innovation Solution
A seal assembly with a roller assembly that includes rolling elements for maintaining rolling contact between the carrier and the aft bearing, reducing friction and allowing small radial movements to maintain clearance, eliminating the need for leakage airflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a radial gap is formed between the rotor shaft and stator vanes, then the rotor can rotate freely, but compressed air or combustion gas leakage occurs leading to reduced efficiency and wear
Solution Approach 1:
A seal assembly is introduced as an intermediary component between the rotor shaft and stator vanes. The seal assembly includes a seal body with a sealing surface that contacts the rotor shaft, and a support structure with a bearing surface that supports the seal body. This intermediary structure prevents direct contact between the rotor and stator while blocking the radial gap to prevent gas leakage.
Solution Approach 2:
The patent replaces the traditional mechanical contact-based sealing system with a bearing-supported seal assembly that uses controlled friction and precise positioning. The bearing surface reduces friction between the seal body and support structure, allowing the seal to maintain contact with the rotor shaft while minimizing energy loss through a different mechanical approach.
2Loss of energy
If traditional sealing methods are used to prevent gas leakage, then leakage is reduced, but friction and wear increase due to continuous contact
Solution Approach 1:
The seal assembly is designed with dynamic characteristics, allowing the seal body to move slightly relative to the support structure through the bearing. This dynamic design enables the seal to adapt to rotor shaft movements while the bearing reduces friction during relative motion. The seal maintains contact pressure for effective sealing while the bearing minimizes wear through reduced friction coefficients.
Solution Approach 2:
The patent changes the friction parameter by introducing a bearing between the seal body and support structure. The bearing provides a controlled friction interface that is significantly lower than direct metal-to-metal contact, thereby reducing wear while maintaining the necessary contact pressure for sealing effectiveness.
3Object-affected harmful factors
If leakage airflow is used to prevent wear, then friction is reduced, but system efficiency decreases due to the need for additional airflow
Solution Approach 1:
The patent replaces the pneumatic wear protection method (using leakage airflow) with a mechanical solution (bearing-supported seal). Instead of relying on airflow to reduce friction and wear, the design uses a bearing mechanism that provides low-friction mechanical support, thereby eliminating the need for additional airflow and improving overall system efficiency.
4Loss of energy
If a seal assembly is introduced to reduce gas leakage, then efficiency improves, but device complexity increases
Solution Approach 1:
The seal assembly is segmented into distinct functional components: a seal body for contacting the rotor shaft, a support structure for mounting, and a bearing surface for reducing friction. This segmentation allows each component to be optimized for its specific function while maintaining overall simplicity. The modular design facilitates manufacturing, assembly, and maintenance.
Solution Approach 2:
The seal assembly serves multiple functions simultaneously: it seals the radial gap to prevent gas leakage, provides structural support through the bearing surface, and reduces friction through the bearing mechanism. By combining these functions into a single integrated assembly, the design avoids the need for multiple separate components, thereby managing complexity while achieving multiple objectives.
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 solution enhances the efficiency of the gas turbine engine by reducing friction and wear while maintaining clearance, thereby improving overall performance and eliminating the need for compressor cooling airflow.
Implementation Method 1
a roller assembly having one or more rolling elements coupled to one of the aft bearing or the carrier, the one or more rolling elements in rolling contact with the other of the aft bearing or the carrier
Data Source
AI summary
A turbine engine includes a rotor, a stator having a carrier, and a seal assembly that is disposed between the rotor and the stator. The seal assembly includes a plurality of seal segments. The plurality of seal segments includes a seal segment having a seal face forming a fluid bearing with the rotor, a body, and an aft bearing extending from the body. The turbine engine further includes a roller assembly having one or more rolling elements coupled to one of the aft bearing or the carrier. The one or more rolling elements in rolling contact with the other of the aft bearing or the carrier.