Intermediate Case Heat Exchanger for Gas Turbine Cooling
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Solution Overview
Problem
The increased overall pressure ratio in gas turbine engines results in hotter air being tapped for cooling turbine components, posing extreme challenges for heat exchangers, which require more efficient cooling air provision due to higher temperatures and increased demands on turbine components.
Innovation Solution
A heat exchanger is mounted in an internal chamber between the core engine housing and an outer intermediate housing, utilizing high-pressure air and air from a lower pressure compressor to cool the high-pressure air, with a bleed valve controlling airflow across the heat exchanger to manage cooling efficiency based on operational conditions, and is constructed from elongated members with fins and potentially superalloy materials like cast nickel alloys with gamma-prime intermetallic phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the overall pressure ratio of the compressor is increased, then the cooling efficiency for turbine components is improved, but the temperature of the tapped air becomes excessively high
Solution Approach 1:
A heat exchanger is introduced as an intermediary device between the high-pressure air source and the turbine components. The heat exchanger uses cooler air from the low-pressure compressor to cool the hot high-pressure air, thereby mediating the temperature difference and enabling effective cooling despite the high overall pressure ratio.
Solution Approach 2:
The cooling air supply system is segmented into two separate air sources: hot high-pressure air from the high-pressure compressor for delivering to turbine components, and cool air from the low-pressure compressor for cooling the hot air in the heat exchanger. This segmentation allows independent optimization of each air stream's temperature and pressure characteristics.
2Reliability
If a heat exchanger is introduced to cool the high-pressure air, then the cooling capability is improved, but the device complexity increases
Solution Approach 1:
The heat exchanger is designed to perform multiple functions: cooling the high-pressure air, managing thermal loads, and adapting to different operating conditions through an integrated valve system. This multi-functionality reduces the need for separate dedicated components for each function.
Solution Approach 2:
The valve system is merged with the heat exchanger assembly, combining the flow control function with the heat exchange function in a single integrated component. This merging reduces the number of separate parts and simplifies the overall system architecture.
3Adaptability or versatility
If a valve is added to control airflow for cooling, then the adaptability to different operating conditions is improved, but the device complexity increases
Solution Approach 1:
The valve is designed to dynamically adjust its opening position based on operating conditions such as power setting and thermal load. This dynamic control allows the system to adapt to varying operational requirements, optimizing cooling efficiency across different flight conditions.
Solution Approach 2:
The valve system is designed to automatically respond to operating conditions without requiring complex external control systems. The valve opening is controlled based on inherent system parameters, enabling self-regulation and reducing the need for additional control infrastructure.
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 solution effectively manages cooling air delivery across varying power operations, ensuring efficient cooling of high-pressure air while reducing compressor load, and is suitable for high-temperature applications with enhanced durability using advanced materials.
Implementation Method 1
Air from the lower pressure compressor is utilized to cool the higher pressure air in the heat exchanger
Implementation Method 2
the heat exchanger is formed of elongated members having fins on an outer surface
Data Source
AI summary
A gas turbine engine has a compressor section including a lower pressure compressor and a higher pressure compressor, and a turbine section. A core engine housing surrounds the compressor section and the turbine section. An outer intermediate housing wall defines an internal chamber between the core housing and the outer intermediate housing. A fan rotor and a fan casing surround the fan rotor to define a bypass duct between the fan case and the outer intermediate housing. A heat exchanger is mounted in the internal chamber and receives high pressure air for cooling the high pressure air and delivering the high pressure air into the core engine housing to be utilized as cooling air for a component. Air from the lower pressure compressor is utilized to cool the higher pressure air in the heat exchanger.