Bearing Compartment Runner Sealing System
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Solution Overview
Problem
Conventional seal systems for gas turbine engines rely on direct oil cooling of runners, which can be inefficient and require complex jet systems, whereas there is a need for alternative methods that allow for passive cooling without direct oil jet application.
Innovation Solution
A sealing system featuring a cylindrical runner with a hollow core made of nickel alloy, configured for an interference fit with a rotating shaft, utilizing passive oil cooling through an extended outer surface and segmented carbon seals, including a non-contacting arch-bound seal and a contacting seal, to manage heat without direct oil jet cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If direct oil jet cooling is used for the runner, then cooling effectiveness is improved, but device complexity and oil consumption increase
Solution Approach 1:
The runner is designed with an extended outer surface that protrudes into the bearing compartment, allowing it to be directly cooled by ambient oil mist without requiring a separate direct oil jet cooling system. The runner essentially cools itself by being exposed to the oil atmosphere already present in the bearing compartment.
Solution Approach 2:
The direct oil jet cooling system is extracted and removed from the design. Instead of using dedicated cooling jets, the system relies on the ambient oil mist environment in the bearing compartment to cool the runner, simplifying the overall cooling system architecture.
2Temperature
If direct oil jet cooling is used for the runner, then cooling effectiveness is improved, but oil consumption increases
Solution Approach 1:
The runner utilizes the ambient oil mist already present in the bearing compartment for cooling, eliminating the need for additional oil consumption dedicated to runner cooling. The same oil that lubricates the bearings also cools the runner through passive convection.
3Temperature
If the outer surface of the runner is extended into the bearing compartment, then passive cooling effectiveness is improved, but the risk of oil ingestion by carbon seals increases
Solution Approach 1:
The sealing system uses different types of carbon seals at different locations: a non-contacting arch-bound seal on the airside and a contacting seal on the oilside. This localized differentiation allows the runner surface to extend into the bearing compartment for effective passive cooling while the sealing system is specifically designed to prevent oil ingestion at each location.
4Temperature
If conventional direct oil cooling is used, then cooling is provided, but compact packaging is difficult
Solution Approach 1:
The dedicated direct oil jet cooling system is removed, allowing for more compact packaging. The runner's extended outer surface provides passive cooling that requires no additional cooling system components, reducing the overall volume required for the sealing system.
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 enables efficient heat management and reduced thermal growth in gas turbine engines by leveraging ambient oil mist for convective cooling, minimizing heat generation and air leakage, and allowing for compact packaging without the need for direct oil jets.
Implementation Method 1
leveraging ambient oil mist for convective cooling
Implementation Method 2
the runner is configured to be fit to the rotating shaft by an interference fit
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
The present disclosure relates to sealing systems for bearing compartments. In one embodiment, a sealing system (200) includes a runner (205) configured to extend circumferentially around a rotating component (206), the runner (205) being formed of a material with low radial thermal growth and configured to fit to the rotating component (206) to remove heat away from the runner (205). The runner (205) can include an outer surface (207) configured to provide passive cooling for the runner (205) in the bearing compartment (215). The sealing system can also include a seal (210) configured to operate with the runner (205), wherein the seal includes a clearance seal on an air side of the runner. The runner (205) can be configured to operate without direct oil cooling.