Gas Turbine Shroud Cooling Circuits
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Solution Overview
Problem
Gas turbine engines face challenges in efficiently cooling components like shroud arrangements, where high temperatures require cooling, but excessive cooling reduces efficiency and increases fuel consumption, necessitating a balance between turbine entry temperature, component life, and specific fuel consumption.
Innovation Solution
A dual-source cooling system for the shroud arrangement using two independent cooling circuits with different temperatures and pressures, where the first circuit cools the upstream portion and the second circuit cools the downstream portion, with air supplied from a downstream direction to optimize temperature and pressure profiles, reducing over-cooling and over-pressurization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If cooling of turbine components is increased to maintain component life at high temperatures, then component life is improved, but efficiency is reduced and fuel consumption increases
Solution Approach 1:
The shroud is divided into multiple cooling circuits (first cooling circuit and second cooling circuit) that are fluidically isolated from one another. Each circuit receives cooling air from different sources with different temperatures and pressures, allowing differentiated cooling strategies for different portions of the shroud to optimize both component life and efficiency.
Solution Approach 2:
Different portions of the shroud receive cooling air with different temperature and pressure characteristics tailored to their specific thermal and mechanical requirements. The first cooling circuit provides cooling air at one temperature/pressure level while the second cooling circuit provides cooling air at another temperature/pressure level, optimizing cooling efficiency for each location.
2Device complexity
If uniform cooling is applied across the entire shroud, then cooling simplicity is maintained, but over-cooling and over-pressurization occur in certain areas
Solution Approach 1:
The cooling system is segmented into multiple independent cooling circuits, each serving specific portions of the shroud. This segmentation allows each circuit to be optimized for its specific function without affecting other areas, preventing over-cooling and over-pressurization while maintaining reasonable system complexity.
Solution Approach 2:
Each cooling circuit is designed to provide cooling air with specific temperature and pressure characteristics matched to the local requirements of the shroud portions it serves. This local optimization prevents harmful over-cooling and over-pressurization effects that would occur with uniform cooling.
3Temperature
If high pressure cooling air is supplied to all shroud areas, then cooling effectiveness is improved, but over-pressurization occurs reducing efficiency
Solution Approach 1:
Different cooling circuits supply cooling air at different pressure levels to different portions of the shroud based on local requirements. This allows high pressure cooling where thermally critical without over-pressurizing areas that require lower pressure, thereby maintaining cooling effectiveness while avoiding efficiency losses from over-pressurization.
Solution Approach 2:
The system changes the pressure parameter of cooling air depending on the location and thermal requirements of different shroud portions. By varying cooling air pressure across different circuits rather than using uniform high pressure, the system achieves effective cooling while minimizing over-pressurization effects.
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 approach enhances the thermal management of shroud components, reduces fuel costs, and improves the life of rotor blade tip clearances by providing tailored cooling to specific areas, maintaining efficiency and reducing specific fuel consumption.
Implementation Method 1
a first cooling circuit within the plate for cooling a first portion of the plate
Implementation Method 2
a second cooling circuit within the plate for cooling a second portion of the plate
Implementation Method 3
one or more chimneys which define one or more inlet passages for one of the first or second cooling circuits
Data Source
AI summary
A seal segment of a shroud arrangement for bounding a hot gas flow path within a gas turbine engine, including: a plate having an inboard hot gas flow path facing side and an outboard side; a bulkhead extending from the outboard side of the plate which defines a fore portion and an aft portion; a first cooling circuit within the plate for cooling a first portion of the plate; a second cooling circuit within the plate for cooling a second portion of the plate; wherein the first cooling circuit is in fluid communication with the fore portion and the second cooling circuit is in fluid communication with the aft portion and the first and second cooling circuits are fluidically isolated from one another. Also described is a method of cooling a seal segment in a gas turbine engine.