Gas Turbine Hub Modification Without Rotor Unstacking
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Solution Overview
Problem
Existing methods to increase gas turbine output require significant effort and downtime due to the need to unstack the rotor for modifying components like the hub and heat shield elements, which is inefficient and costly.
Innovation Solution
A method involving the removal and horizontal storage of the rotor with the hub, mechanical processing of the hub projection, modification of cooling air bores, and installation of new heat shield elements with an optimized design to reduce cooling fluid mass flow, all done without the need to unstack the rotor, thereby minimizing effort and downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rotor is unstacked to modify components like the hub and heat shield elements, then the performance of the gas turbine can be increased, but the effort, time, and costs required for the modification increase significantly
Solution Approach 1:
The heat shield elements are divided into different rows, with the first row through third row remaining in place while only the last row (adjacent to the hub projection) is removed and replaced. This segmentation allows modification of critical components without requiring complete disassembly of the rotor stack.
Solution Approach 2:
The hub projection is completely removed by machining, extracting the problematic structural feature that prevented optimization of the last row of heat shield elements. This extraction enables the installation of improved heat shield elements with better insulation properties without requiring rotor unstacking.
2Power
If the rotor is unstacked to modify components like the hub and heat shield elements, then the performance of the gas turbine can be increased, but the costs associated with the modification increase significantly
Solution Approach 1:
The modification scope is segmented to affect only the last row of heat shield elements and the hub projection, rather than requiring modification of the entire rotor assembly. This reduces labor costs, material costs, and facility requirements while achieving the performance improvement goal.
Solution Approach 2:
The rotor is modified in its installed position on the gas turbine, using the turbine's own structure and available space for the machining operations. The hub projection is machined directly in situ, and the modified heat shield elements are installed without requiring external unstacking facilities, making the modification process more economical.
3Power
If the cooling air bore cross-sectional area is reduced, then the cooling fluid mass flow is reduced and power output increases, but the heat shield elements require improved insulation to maintain adequate cooling
Solution Approach 1:
The heat shield elements in the last row are given enhanced local quality through improved insulation properties compared to standard heat shield elements. This localized improvement in thermal insulation capability allows the heat shields to withstand the higher temperatures resulting from reduced cooling air flow, enabling the power output increase while maintaining component integrity.
Solution Approach 2:
The improved heat shield elements likely utilize composite material structures with superior thermal insulation characteristics. These composite materials provide better heat resistance and thermal barrier properties, allowing the heat shields to function effectively with reduced cooling fluid mass flow while maintaining adequate operating temperatures.
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 effectively increases gas turbine output by reducing the cooling fluid mass flow and improving insulation, while significantly reducing the effort and costs associated with the modification process.
Implementation Method 1
heat shield elements... which insulate a large part of the radially outwardly facing surface of the hub
Implementation Method 2
cooled via cooling air bores formed in the hub
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a method for improving the performance of a gas turbine (1), in which a hub (6) annually surrounding a rotor (2) is machined when the rotor (2) is in the non-stacked state and hot shield elements that are arranged on the hub (6) are exchanged.