Localized Inductive Heating for Gas Turbine Rotor Assembly
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Solution Overview
Problem
Conventional methods for assembling gas turbine rotors require heating entire disks, which is time- and energy-intensive, and results in significant thermal stresses and long cool-down times, affecting the efficiency and duration of the assembly process.
Innovation Solution
A method using localized inductive heating to selectively expand connecting elements of rotor disks, reducing heating and cool-down times by applying heat to specific regions with inductive heating fixtures, allowing for faster assembly and reduced thermal stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hot air blowers are used to heat the entire rotor disk, then the rotor disk achieves sufficient thermal expansion for assembly, but the heating time becomes several hours and energy consumption increases significantly
Solution Approach 1:
The patent applies inductive heating coils only to specific localized regions of the rotor disk where expansion is needed for assembly, rather than heating the entire disk. This selective localized heating achieves the necessary thermal expansion at the connection points while dramatically reducing overall heating time and energy consumption compared to conventional full-disk heating methods
Solution Approach 2:
The heating process is segmented into discrete localized zones using separate inductive heating coils positioned at specific regions of the rotor disk. Each coil independently heats its targeted area, allowing parallel heating of multiple regions and enabling precise control over which portions of the disk expand, thereby reducing total heating time while maintaining assembly precision
2Manufacturing precision
If the entire rotor disk is heated for assembly, then the connecting elements expand sufficiently for interference fit, but the cool-down time requires as many as 24 hours
Solution Approach 1:
By heating only the localized regions containing connecting elements rather than the entire rotor disk, the patent creates a small thermal gradient that cools much faster. The localized heated zones reach ambient temperature and allow interference fit formation in significantly less time than full-disk heating, while still achieving the necessary expansion for proper interference fit quality
Solution Approach 2:
The patent extracts the heating process from being a global operation affecting the entire rotor disk and confines it to only the specific connecting element regions. This extraction of the heating function to localized zones eliminates the need for prolonged cool-down of large disk areas, reducing cool-down time from 24 hours to a fraction of that duration while preserving interference fit quality
3Temperature
If hot air blowers indiscriminately direct hot air at the rotor disk, then the bulk temperature increases for expansion, but thermal stresses are significantly generated in the rotor disk
Solution Approach 1:
The patent uses inductive heating coils to apply heat locally to specific regions of the rotor disk rather than indiscriminately heating the entire disk with hot air blowers. This localized heating generates minimal thermal gradients and consequently reduces thermal stresses in the rotor disk while still achieving sufficient temperature increase in the connecting elements for proper expansion and assembly
Solution Approach 2:
The patent replaces the mechanical hot air blower system with an inductive heating system that uses electromagnetic fields to generate heat directly within the rotor disk material at targeted locations. This substitution eliminates the need for forced convection of hot air across the entire disk surface, thereby avoiding the generation of significant thermal stresses while achieving the required localized temperature increase
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 significantly reduces the time needed to assemble a fully stacked turbine rotor, decreases thermal stresses, and shortens the cool-down period, thereby enhancing the efficiency and speed of the assembly process.
Implementation Method 1
A first inductive heating fixture is applied to a first rotor disk of the plurality of rotor disks. The first inductive heating fixture selectively heats a localized region of the first rotor disk to a target temperature
Implementation Method 2
at least one inductive heating coil disposed within the frame for inductively heating a localized region of the rotor disk when a current is applied to the at least one inductive heating coil
Implementation Method 3
The selective heating of the localized region causes thermal deflection of a connecting element of the rotor disk
Implementation Method 4
When the stacked rotor assembly is allowed to cool, the connecting element contracts into an interference fit with an adjacent rotor disk
Data Source
AI summary
A method of assembling a rotor is provided, in which each rotor disk comprising a connecting element. The method includes: (a) applying heat to a localized region of a first rotor disk of a plurality of rotor disks to selectively deflect a first connecting element of the first rotor disk, wherein the first rotor disk is stationary during heating; (b) installing the first rotor disk onto a rotor stack containing at least one rotor disk; and (c) repeating steps (a) and (b) for each rotor disk of the plurality of rotor disks; and (d) allowing the rotor disks, when stacked, to cool. When cooled, the respective connecting element of each rotor disk that has been selectively deflected contracts into an interference fit with an adjacent rotor disk. A system for selectively heating a localized region of a rotor disk is also provided.