Labyrinth Seal Injection Channels for Turbine Cooling Air Flow Control
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Solution Overview
Problem
In twin-spool turbomachines, the flow rate of cooling air from the high-pressure compressor is often higher than necessary, leading to reduced performance and increased temperature of the cooling air flow, which negatively impacts the cooling efficiency of the high-pressure turbine blades.
Innovation Solution
The turbomachine design incorporates a plurality of channels in the static part of the first labyrinth seal that inject air between the rotating and static parts, reducing the flow rate of cooling air from the impeller and improving the cooling air flow temperature by utilizing an annular bypass space and injection channels to manage air pressure and circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the clearance between the rotating part and static part of the labyrinth seal is increased, then the cooling air flow rate increases, but the turbomachine performance decreases and the cooling air temperature increases
Solution Approach 1:
The first labyrinth seal is divided into multiple sealing zones by adding annular ribs on the rotating part. This segmentation creates multiple narrow gaps instead of one large clearance, reducing the overall cooling air leak rate while maintaining sealing effectiveness across the interface between rotating and static parts.
Solution Approach 2:
The labyrinth seal structure employs asymmetric design where the rotating part has protruding annular ribs that create non-uniform gap distribution. The gap width varies circumferentially, with tighter clearances in critical sealing regions and larger clearances where cooling is less critical, optimizing both performance and cooling requirements.
2Quantity of substance
If the clearance between the rotating part and static part of the labyrinth seal is increased, then the cooling air flow rate increases, but the temperature of the cooling air flow increases
Solution Approach 1:
By segmenting the labyrinth seal into multiple zones with annular ribs, the patent creates multiple flow paths with higher resistance. This reduces the overall cooling air flow rate that leaks through the seal, thereby reducing the temperature rise of the cooling air as it passes through the seal structure.
Solution Approach 2:
The annular ribs act as intermediary structures that mediate the flow of cooling air between the rotating and static parts. These ribs create a series of small obstacles that dissipate energy and reduce the kinetic energy of the cooling air, resulting in lower temperature cooling air reaching the impeller.
3Reliability
If too much cooling air is extracted from the primary flow, then the impeller cooling is sufficient, but the turbomachine performance is considerably reduced
Solution Approach 1:
The labyrinth seal structure with annular ribs enables the system to self-regulate the cooling air flow rate. The increased flow resistance created by the ribs automatically limits the amount of cooling air that can leak through, reducing the need for large clearance adjustments and minimizing the extraction of cooling air from the primary flow while maintaining adequate impeller cooling.
Data Source
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AI summary
The invention relates to a turbine engine (10) including a channel (64) for injecting a secondary air flow (59) of a disk (24) of a high-pressure turbine, leading into a cavity (76) which is substantially isolated, upstream, from a cavity (44) which carries an air flow (48), sampled at the output of a high-pressure compressor, by a first labyrinth seal (78) and, downstream, from a cavity (118) communicating with the primary flow (27) of the turbine engine, by a second labyrinth seal (80). The turbine engine includes channels (128) communicating with the injection channel (64) and connecting through the static portion (100, 101) of the first labyrinth seal (78) between two lips (88a, 88b) of said seal, such as to enable an air flow (134) from the injection channel (64) to be injected between said lips.