Lubrication Containment Test Fixture for Turbine Seal Evaluation
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Solution Overview
Problem
The behavior of lubricant in sump housings of high-speed rotating structures, such as turbine engines, is difficult to predict due to complex air flow patterns, leading to inefficiencies in lubricant scavenging and potential leakage, which compromises the life and effectiveness of radial seal assemblies.
Innovation Solution
A method and test fixture that assess lubricant behavior by allowing controlled leakage from the sump housing, correlating the rate of leakage during testing with actual operational conditions, using a modified radial seal assembly where the static portion is omitted to permit leakage across the rotating portion, and directing test fluid to simulate operational conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a radial seal assembly is used to seal between the sump housing and rotatable structure, then lubricant containment is improved, but lubricant accumulation at the seal runner occurs which compromises seal life and effectiveness
Solution Approach 1:
The static radial seal is removed from the test fixture, extracting the sealing element that would normally prevent lubricant passage. This allows direct measurement of lubricant accumulation at the seal runner location by collecting lubricant that would otherwise be blocked by the seal, enabling evaluation of the seal runner's performance without the confounding presence of the static seal.
Solution Approach 2:
A collector is introduced as an intermediary device to capture and measure the lubricant passing the seal runner location. This mediator quantifies the lubricant accumulation that would occur in service, providing measurable data to evaluate seal runner design without requiring actual operational time or presence of the static seal.
2Measurement precision
If the static radial seal is omitted to permit leakage measurement, then lubricant accumulation measurement is improved, but complete sealing function is lost
Solution Approach 1:
The static radial seal is extracted from the test configuration to eliminate its blocking effect, allowing lubricant to pass freely to the collector for accurate measurement of accumulation rates at the seal runner location.
Solution Approach 2:
The test configuration changes the sealing parameter by removing the static seal, transforming the system from a sealed state to an open state for measurement purposes. This parameter change enables direct observation and measurement of lubricant passage that would otherwise be prevented.
3Reliability
If lubricant is efficiently scavenged from the sump housing, then leakage is reduced, but complex air flow patterns make scavenging behavior difficult to predict
Solution Approach 1:
The test fixture allows the lubrication containment system to self-evaluate by directly measuring lubricant passage through the seal runner location. The system uses its own operational characteristics (lubricant flow, rotation, pressure) to generate measurement data without requiring external simulation or complex flow analysis.
Solution Approach 2:
The complex mechanical analysis of air flow patterns and scavenging behavior is replaced by direct physical measurement of lubricant passage. Instead of modeling and predicting flow patterns, the invention directly measures the outcome (lubricant accumulation) that results from those complex interactions.
Data Source
AI summary
A method for evaluating a lubrication containment system is set forth herein. In one lubrication containment system, a seal runner can be fixed to the rotatable structure and seal against a static radial seal supported by the sump housing. The method also includes the step of rotating the structure relative to the sump housing. The method also includes the step of directing test fluid to the structure inside the sump housing. The method also includes the step of quantifying an accumulation of test lubricant at the seal runner during rotation by omitting the radial seal from the lubrication containment system. As a result, test lubricant can pass out of the sump housing. The amount of test lubricant that passes out of the sump housing, past the location where the seal runner would be or would have been, corresponds to the amount of lubricant that accumulates at the seal runner during operation in the field. It is desirable to minimize this accumulation; accumulation of lubricant at the seal runner can compromise the life and effectiveness of the seal runner. The test results derived from practicing the method can be applied to design aspects of the lubrication containment system, including the seal runner as well as other structures. A test fixture is also set forth for practicing at least one embodiment of the method.