Turbofan Cooled Cooling Air Layout for Higher Turbine Temperatures
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Solution Overview
Problem
Conventional turbofan engine designs are limited by high temperatures at the exit stage of the high pressure compressor, which restrict compressor pressure ratio and exhaust gas temperatures, hindering the ability to operate at higher temperatures for improved performance.
Innovation Solution
Incorporation of a cooled cooling air system that reduces the temperature of airflow using a heat exchanger, allowing components like high pressure turbine rotor blades to withstand higher temperatures, while maintaining or increasing maximum turbofan engine thrust output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional turbofan engine designs are used without cooled cooling air system, then system size and weight are kept minimal, but the engine cannot operate at higher temperatures due to component stress limitations
Solution Approach 1:
The cooling air system is segmented into multiple stages with separate heat exchangers positioned at different locations (forward and aft) to cool air at different pressure levels. This segmentation allows the system to manage thermal loads more effectively and enables operation at higher temperatures without overwhelming any single cooling component.
Solution Approach 2:
A cooled cooling air system acts as an intermediary between the hot combustion gases and the turbine components. The system introduces cooled air as a mediator that reduces the thermal stress on turbine blades and other hot section components, enabling them to withstand higher operating temperatures without direct exposure to full combustion temperatures.
2Temperature
If conventional turbofan engine designs are used without cooled cooling air system, then system weight is kept minimal, but component stress increases at higher temperatures
Solution Approach 1:
The cooling air is cooled in advance before it reaches the turbine components. Heat exchangers positioned in the bypass airflow path pre-cool the cooling air upstream of the turbine, so that when this cooled air is introduced to the turbine section, it immediately reduces component stress and thermal loads, enabling higher operating temperatures.
Solution Approach 2:
The system changes the temperature parameter of the cooling air by using heat exchangers to reduce its temperature before introduction to the turbine section. This parameter change (cooling the cooling air) allows the turbine components to operate at higher temperatures with reduced stress, as the cooled air creates a protective thermal barrier.
3Productivity
If higher compressor pressure ratio and exhaust gas temperatures are implemented, then engine performance is improved, but conventional designs cannot sustain these conditions due to temperature limitations
Solution Approach 1:
The cooling air system is designed to dynamically adjust cooling capacity based on engine operating conditions. By positioning heat exchangers to utilize bypass airflow and allowing the cooling system to adapt to varying engine loads and temperatures, the system maintains optimal temperature control across different performance regimes, enabling sustained high-performance operation.
Solution Approach 2:
The cooled cooling air system serves multiple functions: it cools the cooling air, protects turbine components from thermal stress, and enables the engine to operate across a wider range of performance conditions. This multi-functionality allows the same system to support both conventional and enhanced performance operating modes, providing universal temperature control.
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 cooled cooling air system enables turbofan engines to operate at higher temperatures with improved performance by reducing component stress and maintaining or enhancing thrust output, despite potential increases in system size and weight.
Implementation Method 1
a cooled cooling air system configured to provide a cooling airflow to one or more components exposed to a working gas flowpath of a turbomachine at a location downstream of a combustor of the turbomachine and upstream of an exhaust nozzle of the turbomachine, the cooling airflow being in thermal communication with a heat exchanger for reducing a temperature of the cooling airflow
Data Source
AI summary
A gas turbine engine is provided. The gas turbine engine includes: a turbomachine having a compressor section, a combustion section, and a turbine section arranged in serial flow order, the compressor section having a high pressure compressor defining a high pressure compressor exit area (AHPCExit) in square inches; and a component within the turbomachine, the component including a nickel-based superalloy. The gas turbine engine defines a redline exhaust gas temperature (EGT) in degrees Celsius, a total sea level static thrust output (FnTotal) in pounds, and a corrected specific thrust, wherein the corrected specific thrust is greater than or equal to 42 and less than or equal to 90, the corrected specific determined as follows: FnTotal×EGT/(AHPCExit2×1000).