Impeller Labyrinth Seal Layout for Compressor Tip Leakage
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Solution Overview
Problem
Compressor performance is reduced due to tip leakage and unwanted noise caused by air flowing through the clearance between the stationary housing and rotating blade tips, which leads to pressure losses and swirl-induced inefficiencies.
Innovation Solution
A labyrinth seal arrangement is implemented in the leakage flow path between the shroud and housing, comprising interdigitated shroud and housing rings to create a tortuous flow path, combined with a flow straightening arrangement to remove swirl before reinjection into the impeller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If air is drawn through the impeller for compression, then compressor performance is achieved, but tip leakage causes pressure losses and noise
Solution Approach 1:
The leakage flow path is segmented into multiple sections by introducing a labyrinth seal arrangement with alternating shroud rings and housing rings. This segmentation creates multiple tortuous flow paths that the leaking air must navigate, increasing flow resistance and reducing the volume of air that can leak back to the inlet, thereby reducing pressure losses while maintaining compressor performance.
Solution Approach 2:
The labyrinth seal arrangement acts as an intermediary element between the shroud and housing. This intermediary structure creates a tortuous path with multiple direction changes that impedes the direct leakage flow from outlet to inlet, reducing the rate of air leakage and associated pressure losses without affecting the main compression function.
2Ease of operation
If air flows through the clearance between housing and blade tips, then some leakage occurs, but this creates unwanted noise
Solution Approach 1:
The labyrinth seal arrangement introduces curved and tortuous flow paths instead of straight clearance. The alternating rings create a serpentine pattern that the air must follow, which dissipates energy and reduces the velocity and turbulence of the leakage flow, thereby reducing noise generation while maintaining the necessary rotational clearance.
Solution Approach 2:
The periodic alternation of shroud rings and housing rings creates a repeating pattern of flow direction changes. This periodic structure forces the air to repeatedly change direction, creating a more controlled and less turbulent flow pattern compared to a simple clearance, which reduces noise while allowing operational clearance.
3Productivity
If air leaks back to impeller inlet, then reinjection occurs, but swirling air reduces efficiency
Solution Approach 1:
Instead of allowing the air to follow its natural swirling path back to the inlet, the labyrinth seal arrangement inverts the flow direction multiple times through its tortuous path. The alternating rings force the air to change direction repeatedly, opposing the natural swirl and reducing the rotational momentum of the air when it reaches the inlet, thereby improving efficiency.
4Loss of energy
If shroud and housing rings are interdigitated, then tortuous flow path is created, but device complexity increases
Solution Approach 1:
The labyrinth seal structure serves multiple functions simultaneously: it reduces leakage flow rate, controls noise, manages swirl, and maintains necessary clearances. By integrating this single multi-functional element into the compressor design, the patent achieves multiple performance improvements without proportionally increasing complexity, as the same structural feature addresses multiple technical challenges.
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 labyrinth seal arrangement significantly reduces tip leakage and associated noise, enhancing compressor efficiency and performance by minimizing flow rate and swirl, while the flow straightening arrangement improves airflow homogeneity.
Implementation Method 1
The labyrinth seal arrangement comprises one or more shroud rings interdigitated with one or more housing rings so as to form a tortuous flow path for fluid flowing through the leakage flow path
Implementation Method 2
Known compressor arrangements include an impeller that is rotatable within a stationary housing. The impeller includes a hub and a plurality of impeller blades that extend from the outer surface of the hub
Implementation Method 3
The hub is connected to a rotary shaft that is driven by an electric motor in use
Data Source
AI summary
A compressor is provided for use in domestic appliances. The compressor includes: an impeller including an inlet, an outlet, a hub defining a rotational axis of the impeller, a plurality of impeller blades that extend from the hub, and a shroud that at least partially surrounds the impeller blades; a housing that at least partially surrounds the shroud and that is coaxially arranged with respect to the rotational axis of the impeller to allow the impeller to rotate within the housing; a leakage flow path defined between the shroud and the housing leading from a leakage flow path inlet to a reinjection port, and a labyrinth seal arrangement provided in the leakage flow path. The labyrinth seal arrangement includes one or more shroud rings interdigitated with one or more housing rings so as to form a tortuous flow path for fluid flowing through the leakage flow path.