Dynamic Labyrinth Seal Ring for Shrouded Impeller Leakage Control
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Solution Overview
Problem
Micro-turbine alternator systems in applications like UAVs face inefficiencies due to high operational stresses in shrouded impellers and leakage issues between rotating and stationary components, particularly at high rotational speeds, which can lead to reduced performance and increased tensile stress on blades.
Innovation Solution
A compression ring with a labyrinth seal and load ring configuration is used to apply a radially inward compressive force, reducing operational stresses and sealing leaks by utilizing centrifugal force to adjust the radial gap between the seal and stationary frame, thereby enhancing the efficiency and durability of the compressor assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shrouded impeller is used to reduce leakage, then sealing performance is improved, but tensile stress on blades increases due to operational stresses
Solution Approach 1:
The patent changes the stress state parameter of the impeller by introducing a compression ring that applies radial compressive force. This transforms the blade stress from tensile to compressive, allowing the shrouded impeller to maintain sealing performance while reducing blade stress and preventing fatigue failure.
Solution Approach 2:
The compression ring acts as an intermediary component between the impeller and the centrifugal force. It mediates the stress distribution by converting centrifugal force into radial compressive force on the blades, thereby protecting the blades from tensile stress while maintaining the shrouded structure's sealing function.
2Ease of manufacture
If a fixed radial gap is maintained between labyrinth seal and stationary frame, then manufacturing is simplified, but leakage increases at high rotational speeds
Solution Approach 1:
The patent makes the seal gap dynamic by allowing the compression ring to deform under centrifugal force. The radial gap between the labyrinth seal and stationary frame automatically adjusts with rotational speed, maintaining optimal sealing at high speeds while remaining manufacturable with standard tolerances.
Solution Approach 2:
The patent changes the gap parameter from fixed to variable. The compression ring's elastic deformation causes the radial gap to decrease as rotational speed increases, optimizing the seal performance at high speeds while maintaining ease of manufacture through standard compression ring design.
3Strength
If compression ring applies radial compressive force to reduce blade stress, then blade strength is improved, but operational stresses on the compression ring itself increase
Solution Approach 1:
The patent uses composite material properties by combining the compression ring with the impeller structure. The compression ring is designed with material properties that allow it to withstand operational stresses while transferring compressive force to the blades, creating a composite stress distribution system that protects both components.
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 effectively reduces operational tensile stress on shrouded impellers and minimizes leakage, leading to improved efficiency and extended operational lifespan of micro-turbine alternator systems by managing centrifugal forces and maintaining a sealed environment.
Implementation Method 1
The labyrinth seal is configured reduce the radial gap, using a centrifugal force generated by the load ring as a rotational speed of the compressor assembly increases
Data Source
AI summary
A compression ring for a shrouded compressor including a radially inner surface having one or more areas configured to mate flush with one or more portions of a radially outward surface of a shroud of the shrouded compressor, a radially outer surface located opposite the radially inner surface, a labyrinth seal located on the radially outer surface, a groove located within the radially inner surface, and a load ring located within the groove.