Insulated Cooling Circuit for Gas Turbine Compressor Stators
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Solution Overview
Problem
Current gas turbine engine cooling systems experience significant heat pickup in stator passages, leading to reduced cycle efficiency and power output due to the need for increased cooling air, which is not maintained at a low temperature.
Innovation Solution
An insulated cooling circuit with tubes spaced from the walls of stator passages to form a stagnant air gap, utilizing high-temperature insulation to minimize heat transfer between hot gases and cooling air, thereby reducing heat pickup and maintaining cooling air temperature close to its inlet temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is directed through stator passages in conventional cooling systems, then cooling air is delivered to the compression chamber, but significant heat pickup occurs reducing cycle efficiency and power output
Solution Approach 1:
The patent introduces a stagnant air gap as an intermediary thermal barrier between the hot compression chamber environment and the cooling air passages. This air gap acts as a mediator that reduces direct heat transfer to the cooling air, allowing it to maintain a lower temperature throughout its path through the stator passages.
Solution Approach 2:
The patent converts the harmful hot environment in the compression chamber into a beneficial insulated environment by utilizing the stagnant air gap. The same hot gases that would normally heat the cooling air are now isolated from it, and the heat that would be transferred is instead used to maintain the temperature gradient that drives the insulation effect.
2Reliability
If more cooling air is used to compensate for heat pickup, then blade cooling is maintained, but cycle efficiency and power output are reduced
Solution Approach 1:
The stagnant air gap serves as a thermal intermediary that protects the cooling air from heat ingress, ensuring reliable blade cooling with reduced air flow. This mediator allows the cooling system to maintain effectiveness while operating with less cooling air, thereby preserving more air for power generation.
Solution Approach 2:
The patent changes the thermal parameters of the cooling air by isolating it thermally through the air gap. This parameter change allows the cooling air to enter and traverse the stator passages at a lower temperature, increasing its cooling effectiveness per unit mass and reducing the total quantity needed for reliable blade cooling.
3Device complexity
If tubes are placed close to passage walls for compact design, then device complexity is reduced, but heat transfer from hot gases to cooling air increases
Solution Approach 1:
The stagnant air gap introduces a simple intermediary element between the tube walls and passage walls. This air gap requires no complex insulation materials or active cooling mechanisms, yet effectively reduces heat transfer by utilizing the low thermal conductivity of stagnant air, thus maintaining structural simplicity while achieving thermal isolation.
Solution Approach 2:
The stagnant air gap functions as a thin thermal barrier layer between the cooling air tubes and the hot passage environment. This thin film of stagnant air provides effective thermal insulation without adding significant structural complexity, volume, or weight to the cooling circuit design.
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 results in a substantial reduction in temperature change of the cooling air, requiring less cooling air and increasing cycle efficiency and power output by maintaining a higher inlet temperature for the cooling air, ultimately leading to improved thermal efficiency and reduced heat rejection.
Implementation Method 1
The plurality of tubes are spaced from walls of the respective passages to form a stagnant air gap between the tubes and walls of the respective passages
Implementation Method 2
the stagnant air gap comprises a high temperature insulation to further reduce heat transfer between the hot gas of the gas turbine engine and the cooling air of the cooling circuit
Data Source
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AI summary
A gas turbine engine 110 is provided comprising a compressor 112 with an insulated cooling circuit 310. The compressor 112 comprises a compressor casing 118 having a compression chamber 119 and at least one stator 128 and at least one rotor 126 disposed in the compression chamber 119, the at least one stator 128 comprising a stator body 210 having a plurality of tubes 320 for transporting cooling air 322 through passages 312 in the stator body 210 into the compression chamber 119. The plurality of tubes 320 are surrounded by an air gap 328 for insulating the tubes from the stator body 210.