Gas Turbine Casing Cooling Conduits for Rotor Shaft Thermal Management
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Solution Overview
Problem
Gas turbine rotor shafts experience high temperatures due to proximity to combustion sections, leading to thermal challenges that existing cooling methods fail to adequately address.
Innovation Solution
A heat exchange system integrated into the gas turbine casing, with a supply and return conduit for a cooling fluid, directs the fluid upstream and downstream to transfer heat from the rotor shaft, utilizing compressed air or steam as cooling mediums.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rotor shaft is positioned adjacent to the combustion section to enable power generation, then the gas turbine can produce work through turbine rotation, but the rotor shaft is subjected to high temperatures that cause thermal stress and reduce component lifespan
Solution Approach 1:
A cooling fluid (compressed air or steam) is introduced as an intermediary substance to transfer heat from the rotor shaft to the surrounding environment. The cooling fluid flows through conduits in the casing, absorbing thermal energy from the rotor shaft via thermal conduction through the casing wall, thereby protecting the rotor shaft from excessive temperatures while maintaining its operational position near the combustion section
Solution Approach 2:
The patent utilizes pneumatic cooling by directing compressed air through the casing to cool the rotor shaft. The compressed air flows through the casing interior, absorbing heat from the rotor shaft, and is then discharged through outlets. This pneumatic cooling system enables heat removal without direct mechanical contact with the rotor shaft, resolving the contradiction between maintaining power generation proximity and reducing thermal exposure
2Reliability
If cooling conduits are integrated into the casing to cool the rotor shaft, then thermal stress on the rotor shaft is reduced, but the device complexity increases due to additional inlet, outlet, and conduit structures
Solution Approach 1:
The casing serves multiple functions: it provides structural support for the turbine, contains the cooling fluid pathways, and acts as a heat exchanger surface. By integrating the cooling conduits into the existing casing structure rather than adding separate cooling components, the patent reduces overall device complexity while still achieving effective rotor shaft cooling and thermal stress reduction
Solution Approach 2:
The cooling system is merged with the casing structure by forming inlet, outlet, and conduit features directly in the casing material. This integration combines the protective housing function with the thermal management function, eliminating the need for separate external cooling apparatus and reducing the overall complexity of the gas turbine system
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
Effectively cools the rotor shaft by transferring heat to the cooling fluid, reducing thermal stress and extending component lifespan.
Implementation Method 1
whereby heat is transferred from the rotor shaft to the cooling fluid
Implementation Method 2
directing a supply stream of a cooling fluid within the casing in an upstream direction... and directing a return stream of the cooling fluid within the casing in a downstream direction
Data Source
AI summary
A gas turbine casing with an internal heat exchange system. The gas turbine extends between an inlet section and an exhaust section and defines a downstream direction from the inlet section to the exhaust section. The casing includes a forward end, an aft end downstream of the forward end, a first exterior surface facing radially outward, a second exterior surface facing radially inward, and an internal body at least partially defined between the first exterior surface and the second exterior surface. The heat exchange system includes an inlet and an outlet formed in an exterior surface of the casing proximate the aft end, a supply bore extending upstream from the inlet through the interior body of the casing, and a return bore extending downstream to the outlet through the interior body of the casing.