Turbine Casing Centering via Heat-Protection Wall
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Solution Overview
Problem
Conventional exhaust-gas turbines face efficiency losses due to radial misalignment of the turbine casing relative to the bearing housing, caused by thermal expansion and external forces, leading to contact between turbine blades and the casing wall, resulting in abrasion and reduced efficiency.
Innovation Solution
The use of a heat-protection wall with centering lugs and slots, which allows for infinitely variable positioning of the turbine casing relative to the bearing housing, ensuring accurate centering without additional components or substantial costs, by utilizing materials with higher thermal expansion coefficients to maintain alignment under thermal loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the turbine casing is fastened directly to the bearing housing, then the structure is simple and production costs are low, but the turbine casing becomes offset relative to the bearing housing and turbine shaft due to thermal expansion, leading to blade-casing contact and efficiency losses
Solution Approach 1:
The patent introduces a centering ring as an intermediary component between the turbine casing and bearing housing. This centering ring features a centering surface that ensures precise radial alignment of the turbine casing relative to the bearing housing and turbine shaft, preventing offset caused by thermal expansion while maintaining structural simplicity
Solution Approach 2:
The patent utilizes thermal expansion by designing the centering ring with a centering surface that compensates for radial widening of the turbine casing during thermal loading. The centering mechanism allows the casing to expand while maintaining precise centering relative to the shaft, preventing blade-casing contact
2Manufacturing precision
If groove/ridge connections are used to prevent offset, then centering precision is improved, but the production process becomes more costly and complex due to additional milling operations
Solution Approach 1:
The patent employs a simple centering ring that can be manufactured through basic turning operations rather than expensive milling operations. This centering component provides the necessary precision at low cost, avoiding the need for complex groove/ridge connections while maintaining centering accuracy
Solution Approach 2:
The patent extracts the centering function from the complex groove/ridge connection system and implements it through a separate, simple centering ring. This separation allows the centering function to be achieved through simpler manufacturing processes while maintaining the precision benefits
3Loss of energy
If the air gap between turbine blades and turbine casing is kept small to maximize efficiency, then energy efficiency is improved, but the turbine casing becomes more sensitive to thermal expansion and external forces, increasing the risk of blade-casing contact
Solution Approach 1:
The patent employs the centering ring as a counterbalancing element that compensates for radial widening of the turbine casing during thermal expansion. The centering surface of the ring counteracts the offset tendency, maintaining the small air gap necessary for high efficiency while preventing blade-casing contact under thermal and external loads
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 solution ensures precise centering of the turbine casing and heat-protection wall, maintaining efficiency and preventing misalignment-induced losses, while allowing for adjustable positioning without additional locking mechanisms, thus enhancing the operational stability and efficiency of the exhaust-gas turbine.
Implementation Method 1
a heat-protection wall (2), in the exhaust-gas turbine, defining with the turbine casing (1) an inflow passage (6) leading to the turbine wheel (5), the heat-protection wall (2), in the exhaust-gas turbine, defining with the turbine casing an inflow passage leading to the turbine wheel
Implementation Method 2
Since the centering seat of the turbine casing relative to the bearing housing sometimes widens radially as a result of the large temperature difference between the bearing housing and the turbine casing
Data Source
AI summary
The exhaust-gas turbine comprises a turbine casing, a shaft rotatably mounted in a bearing housing, a turbine wheel arranged on the shaft, and a heat-protection wall, the heat-protection wall defining with the turbine casing an inflow passage leading to the turbine wheel. The heat-protection wall has two seatings, the first seating resting on the bearing housing and the second seating resting on the turbine casing. If the heat-protection wall becomes hot, the two seatings are pressed against the bearing housing and the turbine casing. The turbine casing is pressed outward in the radial direction. Centering of the heat-protection wall and thus also of the turbine casing is ensured by the radially inner seating of the heat-protection wall.