Intercooled Cooling Air System with Bypass for Gas Turbine
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Solution Overview
Problem
Conventional cooling air methods in gas turbine engines require large amounts of airflow to provide sufficient cooling at high pressures and low temperatures, exceeding material limits due to high operating temperatures in the turbine section, necessitating improved cooling air delivery.
Innovation Solution
An intercooled cooling system with a heat exchanger and auxiliary compressor that directs a portion of the cooling airflow to high-pressure components and another portion via a bypass pathway to lower-pressure components, utilizing a bypass valve to regulate airflow, and incorporating a multi-pass heat exchanger for thermal energy exchange with fan bypass airflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling air methods are used to provide sufficient cooling at high pressures and low temperatures, then cooling effectiveness is improved, but large amounts of airflow are required which increases system complexity and reduces efficiency
Solution Approach 1:
The cooling airflow is divided into two separate pathways: a first pathway directs cooled air from the heat exchanger through the auxiliary compressor to high-pressure turbine components, while a second pathway directs bypass air directly to lower-pressure components. This segmentation allows each pathway to be optimized for its specific pressure requirements, reducing total airflow quantity needed while maintaining effective cooling at all locations.
Solution Approach 2:
The heat exchanger acts as an intermediary that cools the compressor discharge air before it enters the auxiliary compressor. This pre-cooling reduces the work input required by the auxiliary compressor and enables more efficient delivery of cooling air to high-pressure components, thereby reducing the overall airflow quantity needed to achieve the same cooling effect.
2Temperature
If large amounts of cooling airflow are used to achieve sufficient cooling at high pressures, then cooling effectiveness is improved, but the work input required for compression increases
Solution Approach 1:
The heat exchanger performs preliminary cooling of the compressor discharge air before it enters the auxiliary compressor. By reducing the temperature of the air beforehand, the density increases and the work required for subsequent compression is reduced, while still delivering sufficient cooling airflow to high-pressure turbine components.
Solution Approach 2:
The system segments the cooling airflow into two pathways, with the auxiliary compressor handling only the portion needed for high-pressure components. The bypass pathway supplies lower-pressure components directly without additional compression, thereby reducing total work input while maintaining cooling effectiveness across all components.
3Temperature
If cooling air is delivered to the highest pressure places of the gas turbine engine, then cooling effectiveness at critical components is improved, but the complexity of the cooling air delivery system increases
Solution Approach 1:
The cooling air delivery system is segmented into two distinct pathways: a first pathway with the auxiliary compressor dedicated to high-pressure turbine components, and a second bypass pathway for lower-pressure components. This segmentation allows each pathway to be independently optimized and controlled, reducing overall system complexity while ensuring adequate cooling at all pressure levels.
Solution Approach 2:
The system incorporates a bypass valve that can dynamically regulate the flow distribution between the two pathways. This dynamic control allows the system to adapt to varying operating conditions and cooling requirements, optimizing performance while managing system complexity through a single adjustable component rather than multiple complex control systems.
4Temperature
If conventional cooling methods are used, then sufficient cooling is provided to turbine components, but the service life of components is reduced due to high operating temperatures
Solution Approach 1:
By segmenting the cooling airflow into targeted pathways, the system ensures that each turbine component receives adequate cooling air at the appropriate pressure and temperature. This targeted cooling more effectively reduces component temperatures, thereby extending service life without requiring excessive airflow that would increase system complexity.
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
Enhances cooling efficiency and reduces the work input required for cooling, improving fuel burn and extending the service life of components by providing targeted cooling to high and low-pressure turbine sections with reduced airflow demands.
Implementation Method 1
the heat exchanger is configured such that the heat exchanger cools the cooling airflow via a thermal energy exchange with a fan bypass airflow of the gas turbine engine
Implementation Method 2
an auxiliary compressor fluidly coupled to the heat exchanger via a discharge duct to compress the cooling airflow exiting the heat exchanger
Data Source
AI summary
An intercooled cooling system for a gas turbine engine includes a heat exchanger in fluid communication with a cooling airflow source directed through the heat exchanger and an auxiliary compressor fluidly coupled to the heat exchanger via a discharge duct to compress the cooling airflow exiting the heat exchanger. A compressor discharge pathway directs a first portion of the cooling airflow from the auxiliary compressor to a first cooling location of the gas turbine engine, and a bypass pathway is fluidly coupled to the discharge duct between the heat exchanger and the auxiliary compressor to direct a second portion of the cooling airflow to a second cooling location of the gas turbine without passing through the auxiliary compressor.