Compressor Clearance Control via Closed-Loop Cooling
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Solution Overview
Problem
Gas turbine engines experience efficiency degradation due to increased compressor clearance caused by thermal expansion during cruise conditions, which is not addressed by existing technologies without impacting takeoff performance.
Innovation Solution
A compressor clearance control system that uses a cooling air source and a defined cooling air flowpath within the compressor casing to minimize thermal expansion by channeling low-temperature, low-pressure cooling air in a closed loop, maintaining minimal clearance between the rotor blade tip and the compressor casing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If compressor components are designed to operate with minimal compressor clearance to enhance thrust production during takeoff, then thrust production at takeoff is improved, but during cruise conditions thermal expansion results in larger compressor clearances that degrade efficiency
Solution Approach 1:
The system changes the temperature parameter of the compressor casing by introducing cooling air, which alters the thermal state of the casing material. This parameter change prevents thermal expansion during cruise conditions, maintaining optimal clearance and improving fuel efficiency without affecting takeoff thrust production
Solution Approach 2:
The patent replaces mechanical clearance adjustment mechanisms with a thermal field-based solution. Instead of mechanically adjusting the position of compressor components to maintain clearance, the system uses thermal cooling to control the dimensional stability of the compressor casing, thereby maintaining optimal clearance passively through temperature control
2Loss of energy
If cooling air is introduced to reduce compressor clearance during cruise conditions, then fuel efficiency is improved, but the complexity of the compressor system increases
Solution Approach 1:
The cooling air system is designed to serve multiple functions: it cools the compressor casing to maintain clearance during cruise conditions, and the same cooling infrastructure can potentially serve other thermal management needs within the compressor system. This multi-functionality reduces the need for separate dedicated cooling systems for different components
Solution Approach 2:
The system uses engine operating parameters (such as bleed air from the engine core) to provide the cooling function. The compressor system essentially serves itself by utilizing resources already present in the engine system, rather than requiring external cooling systems or additional energy input
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 enhances engine efficiency during cruise conditions by preventing thermal expansion, maintaining minimal compressor clearance, and minimizing the impact on thrust production at takeoff, thereby improving fuel efficiency.
Implementation Method 1
operating temperatures of the compressor stages are higher than at takeoff, resulting in larger compressor clearances due to thermal expansion of the compressor components
Implementation Method 2
channeling low-temperature, low-pressure cooling air in a closed loop, maintaining minimal clearance
Data Source
AI summary
In one embodiment, a compressor clearance control system is provided. The compressor clearance control system includes a cooling air source, a compressor casing, and a cooling air flowpath defined through the compressor casing. The flowpath includes an inlet configured to receive cooling air from the cooling air source and an outlet configured to exhaust the cooling air to the cooling air source such that the flowpath defines a closed loop within the compressor.