Gas Turbine Mid-Frame Radial Clearance Adjustment
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Solution Overview
Problem
The radial clearances between the rotor and components in the mid-frame section of a gas turbine engine can shift eccentrically due to centrifugal and thermal loads, leading to premature wear of seals, non-uniform airflow, and reduced efficiency.
Innovation Solution
A radial clearance adjusting assembly is integrated into the mid-frame section, comprising a parallel key adjusting assembly and a torque pin adjusting assembly, which allows for the adjustment of radial clearances to maintain concentricity between the rotor and the compressor exit diffusor and shaft cover, using shims and fasteners to secure the assemblies at specific locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If radial clearances are set by shimming and machining during assembly, then initial concentricity is achieved, but radial clearances shift eccentrically during operation due to centrifugal and thermal loads
Solution Approach 1:
The patent applies the dynamics principle by providing an adjustable radial clearance mechanism that allows the mid-frame section components (compressor exit diffusor and shaft cover) to be repositioned relative to the rotor during operation. This enables dynamic adjustment of radial clearances to compensate for shifts caused by centrifugal and thermal loads, transforming a static clearance setting into a dynamically adjustable system that maintains optimal concentricity throughout the engine's operational lifecycle.
2Device complexity
If radial clearances are fixed during assembly, then manufacturing complexity is reduced, but seal wear increases and efficiency decreases due to eccentric shifts
Solution Approach 1:
The patent applies segmentation by dividing the mid-frame section into adjustable components (compressor exit diffusor and shaft cover) that can be independently repositioned. This segmentation allows for targeted adjustment of radial clearances at specific locations without requiring complete disassembly or complex global adjustments, thereby maintaining relatively simple assembly procedures while enabling improved seal protection and efficiency through operational adjustments.
3Reliability
If adjustable radial clearance mechanism is added, then operational reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies the intermediary principle by introducing adjustable positioning elements (such as shims, spacers, or adjustment mechanisms) as intermediaries between the mid-frame section components and the rotor. These intermediaries facilitate precise control of radial clearances without requiring complex direct coupling or integration, thereby improving reliability through adjustable clearance maintenance while keeping the overall device complexity manageable through the use of standardized intermediary components.
Data Source
AI summary
A mid-frame section of a gas turbine engine having a radial clearance adjustability and a method for adjusting a radial clearance to a rotor in a mid-frame section of a gas turbine engine are presented. The mid-frame section includes a radial clearance adjusting assembly arranged at a compressor exit diffusor. The radial clearance adjusting assembly is configured to adjust the radial clearance to the rotor such that the rotor is concentric with respect to components of the mid-frame section, such as the compressor exit diffusor and shaft cover. The radial clearance adjusting assembly provides radial clearance adjustability in the mid-frame section at multiple locations, such as at forward end and aft end of the compressor exit diffusor. The radial clearance adjusting assembly improves efficiency of the gas turbine and reduces service and operating cost of the gas turbine engine.