Axial Seal Casing Structure for Gas Turbine Pressure Control
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Solution Overview
Problem
In fluid flow machines like gas turbines and aircraft engines, hot gas can leak into the casing structure and cooling air can flow into the flow channel due to pressure equalization through cavities, leading to efficiency losses and increased thermal load.
Innovation Solution
An axial seal is implemented in the casing structure's cavities to prevent pressure equalization, creating distinct pressure regions along the flow channel, thereby reducing exchange flows between the hot gas and cooling air.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pressure equalization is allowed through cavities in the casing structure, then structural flexibility and temperature adaptation are improved, but hot gas leakage into the casing and cooling air loss occur
Solution Approach 1:
The cavity is segmented into multiple pressure zones by axial seals positioned at different axial locations. Each seal divides the cavity into separate regions that can maintain different pressure levels, preventing pressure equalization while allowing the structure to adapt to temperature changes. This segmentation enables the casing to accommodate thermal expansion and contraction without allowing hot gas leakage.
Solution Approach 2:
Axial seals act as intermediary elements between different pressure zones within the cavity. These seals prevent direct pressure equalization between regions while still allowing the overall structure to flex and adapt to temperature changes. The seals serve as mediators that maintain pressure differences necessary to prevent hot gas leakage into the casing.
2Loss of energy
If axial seals are installed to prevent pressure equalization, then hot gas leakage is reduced, but device complexity increases
Solution Approach 1:
The axial seals utilize flexible sealing elements that can deform and adapt to thermal expansion and contraction of the casing structure. These flexible seals maintain their sealing function throughout temperature cycles without requiring complex adjustment mechanisms, thereby reducing overall device complexity while effectively preventing hot gas leakage.
Solution Approach 2:
The sealing system is designed to accommodate parameter changes in temperature and pressure by using seals with appropriate material properties and geometric configurations. The seals can adjust their sealing characteristics in response to changing operating conditions, maintaining effectiveness without requiring complex control systems or multiple sealing stages.
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
The axial seal effectively reduces hot gas leakage into the casing and cooling air loss, enhancing the efficiency and reducing temperatures within the casing structure, thus improving the overall performance of the fluid flow machine.
Implementation Method 1
The axial seal creates at least two regions in a cavity, one behind the other in the axial direction. The axial seal is provided such that different pressure conditions can be created in these regions, the different pressure conditions corresponding to the different pressure conditions in the flow channel along the axial direction.
Implementation Method 2
Pressure equalization can take place through cavities in the casing structure in the axial direction; i.e., along the direction of flow of the hot gas in the flow channel. This pressure equalization produces corresponding gas flows such as, for example, a flow of hot gas from the flow channel into the casing structure or a flow of cooling air from the casing structure into the flow channel.
Data Source
AI summary
A casing structure for a fluid flow machine, in particular for a gas turbine or an aircraft engine, including an outer casing wall and an inner casing wall, which annularly surround a flow channel of the fluid flow machine and are spaced apart in a radial direction with respect to the flow channel. At least one cavity is formed between the inner and outer casing walls. The cavity is axially divided into at least two regions which are separated from each other by an axial seal in such a way that different pressure conditions are created according to the axial position of these regions, which different pressure conditions correspond to the pressure conditions in the flow channel. A corresponding fluid flow machine such as, for example, an aircraft engine.