Air Oil Cooler Ejector Augmentation for Gas Turbine Cooling
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Solution Overview
Problem
The addition of gears to turbofan engines in gas turbine engines increases the need for cooling of additional components, but traditional heat exchangers become oversized to compensate for low airflow at low power conditions, leading to a weight penalty that reduces engine efficiency.
Innovation Solution
An air/oil cooler system with an ejector is introduced to enhance airflow through the heat exchanger, using compressed air to augment cooling during low power conditions, allowing for a smaller, more efficient heat exchanger design that maintains cooling performance across all operational conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the heat exchanger is increased in size to compensate for lower airflow at low power conditions, then cooling capability is maintained, but weight increases and engine efficiency decreases
Solution Approach 1:
The patent applies dynamics by making the airflow through the heat exchanger adjustable rather than fixed. An ejector device is introduced that can be activated selectively to augment airflow through the heat exchanger when cooling demand is high (such as at low power conditions), allowing the heat exchanger to operate effectively at smaller size while maintaining cooling capability across varying operational conditions.
Solution Approach 2:
The ejector device serves as an intermediary that enhances airflow through the heat exchanger on demand. Rather than relying solely on natural airflow which varies with engine power, the ejector acts as a mediator that can be activated to supplement airflow when needed, enabling the heat exchanger to maintain cooling performance without being oversized.
2Weight of moving object
If a smaller heat exchanger is used to reduce weight, then engine efficiency improves, but cooling capability at low power conditions becomes insufficient
Solution Approach 1:
The system dynamically adjusts airflow through the heat exchanger using the ejector device. When the engine operates at low power conditions where natural airflow is insufficient, the ejector is activated to augment airflow, ensuring the smaller heat exchanger can still provide adequate cooling. This dynamic adjustment resolves the contradiction between size/weight and cooling capability.
Solution Approach 2:
The patent changes the airflow parameter through the heat exchanger by introducing the ejector device. The ejector modifies the airflow characteristics (increasing velocity and volume) when activated, allowing a smaller heat exchanger to achieve the same cooling effect that would otherwise require a larger unit operating under less optimized airflow conditions.
3Device complexity
If traditional heat exchanger design is used without airflow augmentation, then device complexity remains low, but cooling performance varies significantly across operational conditions
Solution Approach 1:
The ejector device acts as an intermediary component that bridges the gap between varying natural airflow conditions and consistent cooling requirements. By selectively activating the ejector at low power conditions, the system maintains consistent cooling performance across all operational conditions while adding only minimal complexity compared to traditional fixed-design heat exchangers.
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 provides effective cooling for engine components while minimizing weight penalties and maintaining efficiency, as the air/oil cooler system ensures adequate oil cooling even at low power conditions without the need for oversized heat exchangers.
Implementation Method 1
using compressed air to augment cooling during low power conditions
Implementation Method 2
An air/oil cooler system with an ejector is introduced to enhance airflow through the heat exchanger
Implementation Method 3
Heat exchangers are utilized in such systems to maintain lubricant within desired thermal limits
Implementation Method 4
A heat exchanger may be utilized airflow to cool the lubricant
Data Source
AI summary
An oil supply system for a gas turbine engine has a lubricant pump delivering lubricant to an outlet line. The outlet line is split into at least a hot line and into a cool line, with the hot line directed primarily to locations associated with an engine that are not intended to receive cooler lubricant, and the cool line directed through one or more heat exchangers at which lubricant is cooled. The cool line then is routed to a fan drive gear system of an associated gas turbine engine. A method and apparatus are disclosed. The heat exchangers include at least an air/oil cooler wherein air is pulled across the air/oil cooler to cool oil. The air/oil cooler is provided with an ejector tapping compressed air from a compressor section to increase airflow across the air/oil cooler.