Gas Turbine Oil Cooling With Switchable Bleed and Bypass Air
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Solution Overview
Problem
Existing air-oil heat exchangers in gas turbine engines are often oversized, leading to aerodynamic losses due to excessive airflow requirements, which reduces the work performance of the engine.
Innovation Solution
A fluid thermal control system that utilizes a controllable bleed air valve and airflow inlet valve to selectively use compressor bleed air or bypass air for cooling, optimizing heat exchanger size and minimizing airflow losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heat exchanger is sized to adequately cool the oil during on-ground idle (minimum airflow rate and maximum air temperature), then the oil cooling performance is improved, but the heat exchanger becomes substantially oversized for portions of flight when airflow rate is maximum and air temperature is minimum, leading to increased aerodynamic losses
Solution Approach 1:
The patent applies dynamics by making the heat exchanger airflow adjustable rather than fixed. The system uses controllable valves (airflow inlet valve and bleed air valve) to dynamically regulate the amount of airflow passing through the heat exchanger based on real-time operating conditions. This allows the heat exchanger to operate efficiently across different flight phases without being permanently oversized, thereby reducing aerodynamic losses while maintaining adequate oil cooling performance.
2Reliability
If a larger heat exchanger is used to ensure adequate cooling under all conditions, then the reliability of oil cooling is improved, but the device complexity and weight increase
Solution Approach 1:
The patent applies parameter changes by adjusting the airflow rate parameter through controllable valves rather than changing the physical size of the heat exchanger. The system maintains a fixed heat exchanger size but dynamically changes the airflow parameter to match operating conditions, ensuring reliable cooling without the complexity and weight of an oversized exchanger.
3Temperature
If more airflow is passed through the heat exchanger to improve cooling capacity, then the cooling performance is improved, but the aerodynamic losses increase, reducing the work that can be performed by the airflow
Solution Approach 1:
The system dynamically adjusts the airflow rate through the heat exchanger using controllable valves based on actual cooling needs. During phases when maximum cooling capacity is required (such as high ambient temperature or low airflow conditions), the valves open to allow more airflow. During phases when less cooling is needed, the valves restrict airflow, thereby maintaining cooling performance while minimizing aerodynamic losses and preserving airflow work capability.
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 system provides efficient cooling with a smaller, lighter heat exchanger and reduced aerodynamic losses by dynamically adjusting airflow and bleed air usage based on flight conditions, enhancing engine efficiency and reducing weight.
Implementation Method 1
The heat exchanger is configured to permit heat transfer between a heat exchanger airflow and the flow of engine fluid
Data Source
AI summary
A fluid thermal control system for a gas turbine engine is provided. The gas turbine engine has a compressor section and an engine fluid source that produces a flow of engine fluid. The fluid thermal control system includes an airflow inlet, an airflow outlet, a heat exchanger, an airflow inlet valve, and a bleed air valve. The heat exchanger permits heat transfer between a heat exchanger airflow and the flow of engine fluid. The airflow inlet valve permits the airflow from the source of airflow to engage with the heat exchanger as at least part of the heat exchanger airflow. The bleed air valve is controllable between closed and open configurations. The bleed air valve is in communication with the compressor section and is configured to receive compressor bleed air. In the open configuration, the bleed air valve allows compressor bleed air to engage with the heat exchanger.