Variable Pitch Stator Blade Pivot Wear Reduction
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Solution Overview
Problem
Turbine engine stator blades experience high static and dynamic stresses at the radially internal pivot, leading to potential weakening, cracking, or detachment due to aerodynamic pressure and vibration forces, with existing solutions like cylindrical tubular components concentrating wear at specific contact zones.
Innovation Solution
A tubular component with a first annular zone tightly mounted on the pivot and a second annular zone featuring an annular bulge, allowing radial deformation and creating an annular space with the pivot, which reduces translation movement and distributes stress, improving sliding and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cylindrical tubular component is mounted tightly over the entire surface of the pivot, then wear on the pivot is reduced, but stress concentration occurs at specific contact zones accelerating wear of the tubular component
Solution Approach 1:
The tubular component transitions from a uniform cylindrical structure to a non-uniform structure with an annular bulge that creates distinct zones: a first contact zone with tight mounting for initial positioning, and a second contact zone with the annular bulge for stress distribution. This local differentiation allows each zone to perform its specific function optimally.
Solution Approach 2:
The tubular component is segmented into functionally distinct zones along its length - a first annular zone for tight mounting and a second annular zone with an annular bulge. This segmentation separates the functions of positioning and stress distribution, preventing stress concentration in a single location.
2Reliability
If the tubular component is tightly mounted over the entire pivot surface, then the pivot is protected from wear, but the component complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of providing tight mounting over the entire pivot surface, the solution applies tight mounting only in the first annular zone where it is most needed for positioning, while the second zone with the annular bulge provides protective coverage through a different mechanism, reducing overall complexity.
3Ease of manufacture
If a simple cylindrical bushing is used, then manufacturing is easy and inexpensive, but stress concentration accelerates wear at contact zones
Solution Approach 1:
The geometry of the tubular component is modified by introducing an annular bulge that changes the radial parameter along its length. This parameter change creates the two-zone structure that distributes stress while remaining manufacturable through standard forming processes.
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 solution effectively reduces wear and enhances the service life of variable pitch stator blades by distributing stress over a larger surface area, reducing the risk of damage and improving the operational stability of the turbine engine components.
Implementation Method 1
The tubular component 24 is a cylindrical bushing with a constant radius over its entire height, assembled shrink-fitted on to the internal pivot 14.
Implementation Method 2
a second annular zone comprising an annular bulge extending radially outwards in relation to the pivot axis, wherein the annular bulge and the pivot internally define in conjunction with the pivot an annular space
Data Source
AI summary
An assembly (50) for a turbine engine includes an annular row of stator blades with a longitudinal axis (B) having variable pitch blades each comprising a radial vane (6), at least one of its ends of which is connected to a radially extending pivot (14) and being engaged in rotation around its axis (A) in a ring (16), characterised in that a tubular component (26) is mounted coaxially around the pivot (14), wherein said tubular component (26) comprises a first annular zone (26a) mounted tightly on the pivot (14) and a second annular zone (26b) comprising an annular bulge (28) extending substantially radially outwards in relation to the axis (A) of the pivot (14), wherein the annular bulge (28) and the pivot (14) define an annular space (30).