Gas Turbine Rotor Disk Bore Preheating for Thermal Stress Management
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Solution Overview
Problem
Gas turbine engines face thermal gradient stresses due to rapid temperature increases during take-off, leading to potential disk failure, as the rotor disk bore does not immediately experience the increased heat, causing thermal stress to exceed material limits and reduce disk life.
Innovation Solution
A method involving a temperature regulating and shut-off valve system that delivers preheated air from the combustor to the rotor bore during idle or low-speed operations, with redundant valves for failsafe operation, to manage thermal gradients and prevent excessive heat exposure during take-off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the compressor exit temperature T3 is increased to improve efficiency, then combustion efficiency is improved, but thermal gradient stress in the rotor disk increases causing potential disk failure
Solution Approach 1:
The system preheats the rotor disk bore using hot air from the combustor during idle or low-speed operations before take-off. This preliminary heating action ensures the disk is already warm when rapid power increase occurs, preventing severe thermal gradients and stress during the critical take-off phase while allowing high T3 operation for improved combustion efficiency
2Speed
If the engine speed is increased dramatically during take-off, then thrust is improved, but thermal gradient stress exceeds material limits reducing disk life
Solution Approach 1:
The control system activates the preheat valve to deliver hot air to the rotor disk bore during idle and low-speed operations, preparing the disk thermally before the dramatic speed increase during take-off. This preliminary thermal preparation allows the disk to withstand the rapid acceleration without exceeding material stress limits
3Duration of action of stationary object
If a preheat system is added to manage thermal gradients, then disk life is improved, but device complexity increases
Solution Approach 1:
The system uses hot air from the combustor itself to preheat the rotor disk, rather than requiring an external heating system. The combustor's waste heat is utilized to serve the preheating function, and the control system leverages existing engine parameters (N2 speed, T3 temperature) for automated valve control, minimizing additional system complexity while extending disk life
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 preheats the rotor disk to withstand higher compressor exit temperatures, increasing combustion efficiency and reducing the risk of thermal stress-related failures by controlling the temperature exposure during rapid power increases.
Implementation Method 1
a supply line (127) having an outlet (128) positioned to deliver the hot air into a bore (109) of the rotor disk (104)
Data Source
Figure 1
Figure 2
Figure 3A~5
AI summary
A gas turbine engine (20) comprises a compressor rotor including blades (105) and a disk (104), with a bore defined radially inwardly of the disk (104), and a combustor (112). A tap (116) directs the products of combustion first to a valve (120) and then into the bore of the disk (104). At least two temperature sensors (204,206) sense a temperature of the products of combustion downstream of the valve (120). A control (200) compares sensed temperatures from the at least two temperature sensors (204,206) to ensure the at least two temperature sensors (204,206) are functioning properly. The sensed temperatures are utilized to control the valve (120). A method of operating a gas turbine engine (20) is also disclosed.