Fuel-Cooled Cooling Air System for Gas Turbine Engines
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Solution Overview
Problem
Gas turbine engines face challenges in efficiently cooling the compressor and turbine sections due to increasing air temperatures as overall pressure ratios increase, requiring effective cooling methods to prevent overheating and maintain engine efficiency.
Innovation Solution
A second heat exchanger is mounted downstream of the boost compressor, with fuel being connected downstream to further cool the cooling air in this exchanger, and the cooled air is supplied to the high pressure turbine and exhaust nozzle, utilizing fuel to enhance cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling air systems are used in gas turbine engines, then cooling function is provided, but heat exchanger size increases and cooling efficiency decreases due to increasing air temperatures at higher overall pressure ratios
Solution Approach 1:
The patent changes the thermal parameter of the cooling air by introducing a heat exchanger that cools the cooling air between the compressor outlet and the turbine cooling zones. This parameter change (temperature reduction) enables effective cooling at higher overall pressure ratios without increasing heat exchanger size, directly resolving the contradiction between maintaining cooling effectiveness and limiting heat exchanger volume.
2Productivity
If fuel is used to cool the cooling air in a heat exchanger, then cooling efficiency improves and heat exchanger size reduces, but system complexity increases
Solution Approach 1:
The patent applies multi-functionality by using the fuel stream for dual purposes: first as a cooling medium in the heat exchanger to cool the cooling air, and then as combustion fuel in the combustor. This eliminates the need for separate cooling systems, achieves high cooling efficiency with reduced heat exchanger size, and avoids increasing overall system complexity.
3Reliability
If cooling air is supplied to high pressure turbine and exhaust nozzle, then component overheating is prevented, but engine efficiency may be reduced due to temperature management requirements
Solution Approach 1:
The patent converts the potentially harmful effect of hot cooling air (which would reduce engine efficiency) into a benefit by using a heat exchanger to pre-cool the cooling air with fuel. The fuel, which must be heated to combustion temperature anyway, serves as the cooling medium, thus converting the thermal energy that would have been wasted into useful cooling action, protecting components while maintaining engine efficiency.
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 configuration effectively cools critical engine components, reducing the size of heat exchangers and improving engine efficiency by leveraging the high density and specific heat value of fuel, while maintaining beneficial combustion efficiency.
Implementation Method 1
there is a heat exchanger in which the cooling air is cooled by fuel from the means to supply fuel
Implementation Method 2
the cooling air is cooled by fuel from the means to supply fuel
Implementation Method 3
fuel being delivered for use on the gas turbine engine... the fuel is connected downstream of the first heat exchanger with respect to the direction of flow of the cooling air to further cool the cooling air in the second heat exchanger
Data Source
Figure 1
Figure 2
AI summary
A gas turbine engine (100) includes a main compressor section (101) having a downstream most location (110), a cooling air tap (112) at a location upstream of the downstream most location (110), and a main turbine section (104, 106). The main turbine section (104, 106) and the main compressor section (101) are mounted within a housing, and each have rotatable components. A first heat exchanger (130) is connected to the cooling air tap (112) and to receive fuel to be supplied to a combustor (102), such that the fuel may cool the cooling air in the first heat exchanger (130). A boost compressor (128) is connected to receive air downstream of the first heat exchanger (130) and connected to deliver the cooling air to at least one of the rotatable components in at least one of the compressor and turbine sections (101, 104, 106).