Gas Turbine Disk Hub Axial Stress Reduction
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Solution Overview
Problem
High axial stress in high pressure turbine (HPT) disk hubs of gas turbine aircraft engines due to severe thermal gradients during takeoff leads to reduced engine life, with existing solutions negatively impacting performance or requiring weight and thermal adjustments.
Innovation Solution
Geometric features such as a chamfer in the inner diameter, radial grooves, and material removal along axial stress isolines are introduced into the disk hub to mitigate high axial stress, with design optimization using computer analysis to balance stress reduction and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the disk rim load is reduced to meet life requirements, then the axial stress life is improved, but the blade weight is reduced and performance is negatively impacted
Solution Approach 1:
The patent applies local quality by introducing geometric features (chamfers, radial grooves, and material removal along axial stress isolines) specifically at the hub location where axial stress is highest. This localized modification reduces axial stress without requiring global changes to the entire disk or blades, thereby maintaining blade weight and performance while improving hub life.
2Duration of action of stationary object
If the hub size is increased to accommodate axial stress, then the axial stress life is improved, but the weight and thermal performance of the disk are negatively impacted
Solution Approach 1:
Instead of increasing the overall hub size, the patent applies localized geometric modifications (chamfers, radial grooves, and material removal) specifically at stress-concentration areas. This localized approach reduces axial stress without requiring increases in hub dimensions, thereby avoiding negative weight and thermal performance impacts.
3Stress or pressure
If the idle hub flow is increased to warm the disk prior to takeoff, then the axial stress is reduced, but the system performance is negatively impacted
Solution Approach 1:
The patent applies preliminary action by pre-warming the disk during the idle hub flow phase before takeoff. This preliminary thermal conditioning reduces the thermal gradient and associated axial stress during critical takeoff operations, thereby reducing stress without requiring continuous high flow during all operating phases and minimizing impact on system performance.
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 proposed design effectively reduces axial stress without compromising engine performance, increasing engine life from 11,000 to 15,300 cold start cycles, while minimizing undesirable stress variations.
Implementation Method 1
geometric features are introduced into the disk hub to mitigate high axial stress... a chamfer is formed into the inner diameter of the disk hub... radial grooves are formed in the hub surface
Implementation Method 2
hub material is removed along a line parallel to an axial stress isoline
Data Source
AI summary
A gas turbine engine disk that includes a centrally disposed disk hub having an integrally-formed, radially outwardly extending web terminating at an outer end. The disk hub has a radially-displaced annular hub surface exposed to high pressure, high temperature discharge gases during engine operation. The radially-displaced annular hub surface acts as an axial free surface mitigating the formation undesirable axial stress in the disk hub.