Turbine Compressor Variable-Pitch Vane Control Ring
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Solution Overview
Problem
Turbine engine compressors face inefficiencies due to non-uniform gas flow and high forces at high speeds, which require adaptive pitch angles for stator vanes but are hindered by conventional crank-arm systems with fixed lengths and rigid control rings.
Innovation Solution
The introduction of oblong holes in the control ring that allow for adjustable pitch angles of stator vanes by accommodating pins of varying lengths, enabling individual or group adjustments to match gas flow heterogeneity and compensate for control ring deformations at high speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional crank-arms of fixed length are used in the control ring, then the structure is simple and manufacturing is easy, but the pitch angles of stator vanes cannot be individually adjusted to match gas flow heterogeneity
Solution Approach 1:
The control ring incorporates different hole shapes (circular vs. oblong) at different circumferential positions to provide localized pitch angle adjustment capabilities. This allows specific regions of the control ring to adapt to local gas flow conditions while maintaining overall structural simplicity.
Solution Approach 2:
The system enables dynamic adjustment of pitch angles by allowing the control ring to rotate and axially move, with oblong holes permitting the pins to move within them. This dynamic capability allows the pitch angles to be adapted during operation to match varying gas flow conditions.
2Reliability
If all stator vanes are positioned in the same angular position for a given control ring position, then the control system is simple, but it cannot correct control ring deformations caused by high forces at high engine speeds
Solution Approach 1:
Different groups of stator vanes are assigned different pitch angle adjustment characteristics through the control ring's varied hole shapes. This allows individual vanes or groups of vanes to be positioned at different angular positions to compensate for local deformations or gas flow conditions.
Solution Approach 2:
The control ring is effectively segmented into different functional zones with different hole types (circular for fixed position, oblong for adjustable position). This segmentation enables independent adjustment of different vane groups to address localized issues such as deformation or non-uniform gas flow.
3Manufacturing precision
If the control ring is made rigid to maintain structural integrity, then manufacturing precision is maintained, but it cannot accommodate the path of pins during rotation and axial movement
Solution Approach 1:
The control ring is designed with dynamic movement capabilities, allowing it to rotate around the compressor axis and move axially to accommodate the pins' paths. This dynamic design enables the rigid control ring structure to function effectively with varying pin positions without compromising manufacturing precision.
Solution Approach 2:
The control ring's ability to move in multiple dimensions (rotation around axis plus axial movement) provides the necessary freedom to accommodate pin trajectories. This multi-dimensional capability allows the rigid ring structure to maintain precision while accommodating dynamic pin positioning requirements.
Data Source
AI summary
A turbine engine compressor includes a stator featuring an annular casing and at least one annular row of variable-pitch vanes, wherein each vane comprises a radially external end having a pivot mounted in an orifice in the casing and connected by a linking member to an control ring capable of pivoting axially in relation to the casing, where the linking member comprises a first end fixed to the pivot of the vane and a second end having a pin inserted in a hole in the control ring, where at least one of the holes in the control ring serves for insertion of the pins of the linking members, is oblong in shape and extends in the circumferential direction in order to allow movement of the pin in the oblong hole, during rotation of the control ring.