Rotatable Heat Exchanger for Gas Turbine Bleed-Air Cooling
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Solution Overview
Problem
Bleed air from the high-pressure compressor in gas turbine engines, used to pressurize bearing compartments, is typically at high temperatures, degrading seals and potentially leading to oil leakage due to excessive heat, despite previous assumptions that incorporating a rotatable heat exchanger would create excessive drag and be difficult to control.
Innovation Solution
A compact, shaft-mounted rotatable heat exchanger is designed to cool the bleed air using lubrication oil as a cooling fluid, with concentric cylindrical plates and helical passages that rotate with the shaft, allowing efficient heat transfer between the bleed air and oil, minimizing drag and operational challenges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rotatable heat exchanger is incorporated to cool the bleed air, then the seal life is extended and oil leakage is prevented, but the drag increases and operational control becomes difficult
Solution Approach 1:
The heat exchanger is designed to rotate at variable speeds rather than operating at fixed speed. The rotational speed can be adjusted dynamically to optimize the balance between cooling effectiveness and drag reduction, allowing the system to adapt to different operating conditions and minimize energy losses while maintaining reliable seal operation
Solution Approach 2:
The system changes the rotational speed parameter of the heat exchanger to control both the cooling performance and drag characteristics. By adjusting this key parameter, the system can achieve optimal cooling of bleed air to protect seals while minimizing the drag penalty associated with rotating components
2Reliability
If a rotatable heat exchanger is incorporated to cool the bleed air, then the seal life is extended and oil leakage is prevented, but the device complexity increases
Solution Approach 1:
The heat exchanger is integrated directly into the rotor shaft assembly, merging the cooling function with the existing rotational structure. This combination eliminates the need for separate mounting structures and reduces overall system complexity while achieving reliable seal protection through effective bleed air cooling
3Reliability
If a rotatable heat exchanger is incorporated to cool the bleed air, then the seal life is extended, but the ease of operation decreases
Solution Approach 1:
The heat exchanger utilizes the existing rotational motion of the rotor shaft to drive its operation, rather than requiring an independent power source or complex control system. The system serves itself by harvesting the mechanical energy already present in the engine, simplifying operational control while maintaining reliable seal protection through continuous cooling
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 rotatable heat exchanger effectively cools the bleed air, extending seal life and preventing oil leakage while maintaining engine efficiency and reducing operational costs.
Implementation Method 1
A compact, shaft-mounted rotatable heat exchanger is designed to cool the bleed air using lubrication oil as a cooling fluid, with concentric cylindrical plates and helical passages that rotate with the shaft, allowing efficient heat transfer between the bleed air and oil
Data Source
AI summary
A rotatable heat exchanger includes a first manifold assembly, a second manifold assembly, and a core extending axially from the first manifold assembly to the second manifold assembly. The first manifold assembly, the core, and the second manifold assembly are formed to mount around and rotate with a shaft. The core includes a plurality of helical passages that extend from the first manifold assembly to the second manifold assembly. The plurality of helical passages includes a plurality of first-fluid passages fluidly coupled to the first manifold assembly and to the second manifold assembly, and a plurality of second-fluid passages fluidly coupled to the first manifold assembly and the second manifold assembly.