Asymmetric Stiffness Pitch Control Ring for Turbomachines
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Solution Overview
Problem
Variable stator vane pitch control rings face precision degradation due to asymmetric mechanical load caused by gas flow and rotation, leading to uneven deformation and increased weight when enhanced with multiple turnbuckle mechanisms for stiffness.
Innovation Solution
A pitch control ring composed of two halves with differing stiffnesses, where one half is lightweight and flexible, and the other is more rigid, connected at a clevis with a single control mechanism, to mitigate deformation and weight issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the ring stiffness is increased to reduce deformation under asymmetric load, then the precision of angular pitch is improved, but the weight of the device increases
Solution Approach 1:
The control ring is divided into two halves with different structural configurations: one half has a continuous cross-section providing higher stiffness, while the other half has a reduced or interrupted cross-section providing lower stiffness. This local differentiation allows each half to be optimized for its specific loading conditions, achieving adequate precision without uniformly increasing the weight of the entire ring structure.
Solution Approach 2:
The invention introduces asymmetric structural design in the control ring by making the two halves have different stiffness characteristics. This asymmetry directly addresses the asymmetric loading conditions caused by gas flow direction and rotation moment, allowing the ring to better accommodate the uneven force distribution without requiring overall reinforcement that would increase weight.
2Measurement precision
If multiple turnbuckle mechanisms are distributed around the ring circumference to control rotation, then the stiffness and precision are improved, but the device complexity and weight increase
Solution Approach 1:
The control ring is segmented into two distinct halves with different structural properties, allowing each segment to be independently optimized. This segmentation enables the use of a single turnbuckle mechanism to effectively control the ring rotation, as each half can deform appropriately under the applied load without requiring multiple distributed control points.
Solution Approach 2:
The invention changes the structural parameter (cross-section configuration) of different parts of the ring to achieve the desired stiffness distribution. By modifying the geometric parameters of the ring halves rather than adding multiple control mechanisms, the system achieves adequate precision with a simpler, single-turnbuckle control system.
Data Source
AI summary
An angular pitch control ring (8) of stator vanes (2), the rotations of which are controlled by a mechanism (6) applying a thrust tangent to the ring (8), is also moved in translation when it is displaced, making it touch the stator (2). According to the invention, one lateral region (13) on one side of the mechanism (6) is constructed to be stiffer than the other region to take account of the larger forces that the mechanism (6) must apply in a direction of movement. Application to turbomachines.