Gas Turbine Diffuser Aft Plate Assembly Stress Reduction
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Solution Overview
Problem
Traditional diffuser sections in gas turbine engines experience high stresses due to high temperatures and exhaust gases, leading to increased wear and reduced mechanical integrity.
Innovation Solution
The implementation of a modified diffuser section design featuring an aft plate assembly with notches and ridges for axial installation and retention within a circumferential groove, combined with a curved shape achieved through a spinning process, and the use of poles and discrete brackets to reduce stress and improve mechanical integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional diffuser section is used, then the structure is simple and easy to manufacture, but it experiences high stresses and increased wear due to high temperatures and exhaust gases
Solution Approach 1:
The diffuser section is divided into multiple components including an inner barrel, outer barrel, aft plate assembly, forward plate, and poles. This segmentation allows each component to be optimized independently for stress resistance and thermal management, improving overall mechanical integrity while maintaining manufacturability through modular assembly
Solution Approach 2:
The patent introduces a circumferential groove feature that enables rotational adjustment of the aft plate assembly from a first circumferential orientation to a second circumferential orientation. This dimensional change allows the ridges to transition from an aligned state (higher stress concentration) to an offset state (reduced stress concentration), thereby reducing hoop stresses and thermal gradients without complicating the basic diffuser structure
2Power
If the diffuser section is subjected to high temperatures and exhaust gases, then the turbine can operate at high power, but the diffuser experiences high stresses and increased wear
Solution Approach 1:
The aft plate assembly with ridges and the circumferential groove act as intermediary elements between the hot exhaust gases and the diffuser structure. By rotating the aft plate assembly to the second circumferential orientation, the ridges create offset pathways that mediate the thermal and mechanical stresses, reducing hoop stresses and thermal gradients while allowing the turbine to operate at high power
Solution Approach 2:
The design allows the aft plate assembly to be rotated from a first circumferential orientation to a second circumferential orientation, creating a dynamic adjustment capability. This dynamic positioning enables optimization of stress distribution under different operating conditions, reducing thermal stress and wear while maintaining high turbine power output
3Ease of operation
If the aft plate assembly is inserted axially into the circumferential groove, then installation is simplified, but the plate must be rotated to achieve proper retention
Solution Approach 1:
The circumferential groove is pre-formed with a specific cross-sectional shape that guides the ridges of the aft plate assembly during axial insertion. This preliminary preparation ensures that the ridges naturally follow the groove contours, facilitating easy axial installation without requiring complex alignment tools or procedures
Solution Approach 2:
The interaction between the ridges and the circumferential groove creates a self-retaining mechanism. When the aft plate assembly is rotated to the second circumferential orientation, the ridges engage with the groove walls in a way that provides automatic retention without additional fasteners or complex locking mechanisms, simplifying both installation and the retention system
Data Source
AI summary
A method includes inserting axially a radially interior surface of an aft plate assembly into a circumferential groove of an inner barrel of a diffuser section of a gas turbine, where the aft plate assembly is inserted into a first circumferential orientation relative to the circumferential groove, and the circumferential groove is disposed on a radially exterior surface of the inner barrel. The method includes rotating the aft plate assembly circumferentially within the circumferential groove from the first circumferential orientation to a second circumferential orientation, where the inner barrel is configured to axially retain the aft plate assembly when the aft plate assembly is disposed in the second circumferential orientation.