Intercooled Cooling Air Supply for Gas Turbine Rotating Components
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Solution Overview
Problem
Modern gas turbine engines face challenges in efficiently supplying cooling air to rotating components due to increasing compressor pressures and temperatures, which existing cooling systems fail to adequately address.
Innovation Solution
An intercooled cooling air supply system is implemented, featuring a cooling compressor, heat exchanger, mixing chamber, and control mechanisms such as a clutch and shut-off valve, which ensures efficient cooling air delivery to high-pressure compressor and turbine sections by maintaining a pressure ratio greater than or equal to 1.02 and strategically positioning components like the heat exchanger within a recessed chamber to optimize airflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cooling system is provided for rotating components in high-pressure compressor and turbine sections, then cooling effectiveness is improved, but system complexity and energy loss increase
Solution Approach 1:
The cooling system is segmented into multiple independent components: a cooling compressor, a heat exchanger, and flow control means. This allows each component to perform its specific function efficiently while enabling independent control and maintenance of each segment, thereby improving cooling effectiveness without proportionally increasing overall system complexity.
Solution Approach 2:
The cooling compressor compresses cooling air in advance before it reaches the rotating components, and the heat exchanger pre-cools the compressed air. This preliminary action ensures that cooling air is ready at the required pressure and temperature before being supplied to the turbine and compressor sections, improving cooling effectiveness while allowing the use of simpler on-demand flow control mechanisms.
2Reliability
If cooling air is supplied to rotating components during high-power operations, then cooling effectiveness is improved, but energy loss increases at lower power levels
Solution Approach 1:
The flow control means dynamically adjusts the flow rate of cooling air based on engine power level and cooling requirements. During high-power operations, the valve opens to supply maximum cooling air; during lower power operations, it restricts or stops cooling air flow. This dynamic control ensures cooling effectiveness when needed while minimizing energy loss during partial-power operations.
Solution Approach 2:
The system changes the flow rate parameter of cooling air according to operating conditions. The flow control means modifies the cooling air flow rate to match the thermal load of rotating components at different power levels, maintaining adequate cooling during high-power operations while reducing or eliminating cooling air consumption during lower power operations to minimize energy loss.
3Stress or pressure
If a cooling compressor is used to compress cooling air, then cooling air pressure is improved, but use of energy increases
Solution Approach 1:
The cooling compressor continuously compresses cooling air whenever the engine is operating, maintaining a ready supply of pressurized cooling air. This continuous operation ensures that cooling air is always available at the required pressure for immediate supply to rotating components, eliminating the need for complex pressure regulation systems and reducing energy waste associated with intermittent compression and pressure management.
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 system effectively cools high-pressure turbine and compressor components, improving engine efficiency and reducing fuel consumption by ensuring adequate cooling air supply, especially during high-power operations, while minimizing inefficiencies at lower power levels.
Implementation Method 1
A heat exchanger is connected downstream of the first tap
Implementation Method 2
A cooling compressor is connected downstream of the heat exchanger
Data Source
Figure 1
Figure 2A
Figure 2B~2D
AI summary
A gas turbine engine (20) includes a plurality of rotating components housed within a main compressor section (106) and a turbine section (108). A first tap (118) is connected to the main compressor section (106) and configured to deliver air at a first pressure. A heat exchanger (124) is connected downstream of the first tap (118). A cooling air valve (152) is configured to selectively block flow of cooling air across the heat exchanger (124). A cooling compressor (134) is connected downstream of the heat exchanger (124). A shut off valve (132) stops flow between the heat exchanger (124) and the cooling compressor (134). A second tap (161) is configured to deliver air at a second higher pressure. A mixing chamber (138) is connected downstream of the cooling compressor (134) and the second tap (161) and configured to deliver air to at least one of the plurality of rotating components. A system (146) stops flow between the cooling compressor (134) and the plurality of rotating components. A controller (133) is configured to modulate flow between the heat exchanger (124) and the plurality of rotating components under certain power conditions of the gas turbine engine (20), and programmed to control the cooling air valve (152), the shut off valve (132) and the system (146) such that flow is stopped between the heat exchanger (124) and the cooling compressor (134) only after the cooling compressor (134) has been stopped.