Movable Door Cooling Air System for Turbofan Engines
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Solution Overview
Problem
In turbofan gas turbine engines, the flow rate of redirected fan air is often insufficient to adequately cool extracted turbine cooling air, leading to parasitic losses during certain operational levels.
Innovation Solution
A system featuring a heat exchanger with a movable door that selectively directs fan air flow to cool turbine cooling air, ensuring sufficient cooling while minimizing engine losses, comprising a turbofan engine with a bypass flow passage and multiple heat exchangers configured to transfer heat between engine air and fan air, with doors controlling the flow to optimize cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fan air is continuously redirected to cool turbine cooling air, then cooling adequacy is improved, but parasitic engine losses increase
Solution Approach 1:
The system employs a movable door that can change position between open and closed states, allowing the cooling system to dynamically adjust fan air flow based on operational conditions. This dynamic configuration enables the system to provide adequate cooling when needed while eliminating unnecessary parasitic losses when cooling demand is low, directly resolving the technical contradiction between cooling adequacy and energy efficiency.
Solution Approach 2:
The system changes the flow rate parameter of fan air dynamically based on engine operational levels. By adjusting the amount of fan air redirected to the heat exchanger according to actual cooling demand, the system ensures adequate cooling temperature while minimizing energy wastage during operational levels where full cooling capacity is not required.
2Temperature
If fan air flow rate is increased to ensure adequate cooling, then cooling effectiveness is improved, but engine efficiency deteriorates
Solution Approach 1:
The system incorporates a control mechanism that responds to cooling demand conditions and adjusts fan air flow accordingly. This feedback-based control ensures that fan air flow rate matches actual cooling requirements, maintaining adequate cooling effectiveness while optimizing engine efficiency by avoiding excessive air flow that would reduce overall engine performance.
3Temperature
If fan air is redirected through heat exchangers, then turbine cooling air is adequately cooled, but parasitic losses are incurred
Solution Approach 1:
The movable door enables dynamic control of air flow through the heat exchangers, allowing the system to activate cooling only when turbine cooling air temperature requires it. This dynamic operation eliminates parasitic losses associated with continuous cooling when the extracted air temperature is already adequate, resolving the contradiction between effective cooling and energy loss reduction.
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 ensures adequate cooling of turbine cooling air while significantly reducing parasitic engine losses by optimizing fan air flow through the heat exchangers, enhancing thermodynamic efficiency and reducing energy wastage.
Implementation Method 1
The heat exchanger is configured to transfer heat between the fluid and the cooling air
Data Source
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AI summary
A system for supplying turbine cooling air flow includes a turbofan engine, a heat exchanger, and a door. The turbofan engine includes an engine case that has an inner volume within which at least a gas turbine engine is mounted, and a bypass flow passage that is defined by an outer fan duct and an inner fan duct and that is configured to direct fan air flow therethrough. The heat exchanger is disposed within the turbofan engine, is coupled to receive fluid and cooling air from the bypass flow passage, and is configured to transfer heat between fluid and the cooling air. The door is movably mounted in the turbofan engine and is movable between a closed position, in which the cooling air will not flow through the heat exchanger, and an open position, in which the cooling air may flow through the heat exchanger.