Gas Turbine Rotor Segmentation for Creep Resistance
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Solution Overview
Problem
Gas turbine rotors with hollow shafts face high mechanical and thermal loads, leading to creep deformations and reduced service life due to the transmission of driving energy and exposure to the combustion chamber's heat, causing mechanical defects and premature fatigue.
Innovation Solution
The rotor is designed with I-shaped rings that reduce mechanical stresses and thermal loads by replacing the hollow shaft with shorter, axially stacked rings, incorporating radial webs for improved thermal insulation and using tension bolts for clamping and support, along with Hirth-type toothing for slip-free torque transmission and labyrinth-like seals for cooling air guidance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a hollow shaft is used to transmit driving energy from the turbine disk to the compressor disk, then energy transmission is achieved, but the hollow shaft is subjected to high mechanical loads causing creep deformations and reduced service life
Solution Approach 1:
The hollow shaft is divided into multiple axially stacked rings that are clamped together by tension bolts. This segmentation reduces the mechanical load on each individual ring compared to a single long hollow shaft, thereby reducing creep deformations and extending service life while maintaining the energy transmission function through the stacked configuration.
2Device complexity
If the hollow shaft is positioned radially adjacent to the combustion chamber, then structural arrangement is achieved, but thermal loads from the combustion chamber heat the axial region of the rotor causing reduced strength and rigidity
Solution Approach 1:
The hollow shaft is segmented into multiple rings with axial gaps between them. This segmentation creates thermal insulation zones that reduce heat transfer from the combustion chamber to the rotor rings, thereby maintaining the strength and rigidity of the hollow shaft structure while preserving the compact structural arrangement.
Solution Approach 2:
The axial gaps between the rings act as thermal insulation intermediaries, reducing the direct thermal path from the combustion chamber to the rotor. This intermediary structure protects the hollow shaft from excessive thermal loads while maintaining the necessary structural configuration.
3Ease of manufacture
If the hollow shaft is made from a single continuous structure, then manufacturing is simplified, but the long axial length increases susceptibility to mechanical defects and fatigue
Solution Approach 1:
The hollow shaft is constructed from multiple discrete rings that are clamped together. Each ring can be manufactured separately with shorter axial length, reducing the probability of manufacturing defects and fatigue issues compared to a single long hollow shaft. The rings are then assembled using tension bolts, maintaining structural integrity while improving reliability.
4Stability of the object's composition
If tension bolts are used to clamp the rings together, then mechanical integrity is maintained, but the clamping force creates additional stress concentrations
Solution Approach 1:
The tension bolts merge the multiple discrete rings into a unified stacked structure. By distributing the clamping force across multiple bolts and optimizing the bolt placement, the mechanical integrity of the assembly is maintained while the stress concentrations are dispersed rather than concentrated at single points, reducing the overall impact on the structure.
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 design extends the service life of the rotor by reducing mechanical and thermal stresses, allowing the use of cost-effective materials and preventing creep deformations, while maintaining efficient energy transmission and cooling, thus enhancing the mechanical integrity and durability of the rotor.
Implementation Method 1
incorporating radial webs for improved thermal insulation
Implementation Method 2
using tension bolts for clamping and support
Implementation Method 3
Hirth-type toothing for slip-free torque transmission
Implementation Method 4
labyrinth-like seals for cooling air guidance
Data Source
AI summary
The invention relates to a rotor for a non-positive-displacement machine provided with a hollow shaft, which is arranged coaxial to the rotation axis, is supported, on both sides and on the face, on two axially opposed sections of the rotor, and which encloses an inner hollow space. In order to provide a rotor for a non-positive-displacement machine, which has a higher serviceable life and is less susceptible to mechanical defects, the invention provides that the hollow shaft, in the axial direction of the rotor, is formed from a number of adjoining rings, and the rings are outwardly sealed against one another an with regard to the sections of the hollow space. Each ring has an I-shaped cross-section and the web of the I shape extends in the radial direction of the rotor.