Piezoelectric Shroud Actuation for Turbomachine Clearance Control
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Solution Overview
Problem
Existing axial turbomachine sealing devices have limited efficiency and adaptability to varying flight conditions, with current solutions being either inefficient or bulky, and lacking effective means to detect and adjust radial clearance between rotor blades and external shrouds.
Innovation Solution
An external casing with a circular wall featuring an internal annular groove and piezoelectric actuators arranged in two annular rows, allowing for precise adjustment of the shroud's position and clearance measurement, powered individually and protected by an insulating layer, to optimize sealing and adaptability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If elastic elements are used to connect the shroud to the casing, then the sealing device can adapt to different flight conditions, but the efficiency gain remains limited and the number of configurations is restricted
Solution Approach 1:
The patent replaces traditional elastic mechanical elements with piezoelectric actuators that convert electrical signals directly into precise mechanical displacement. This substitution enables active control of the shroud position with much finer resolution and greater adaptability to varying flight conditions, thereby improving efficiency while maintaining adaptability.
Solution Approach 2:
The invention changes the control parameter from passive elastic deformation to active piezoelectric displacement controlled by electrical signals. This allows dynamic adjustment of the shroud position based on real-time flight conditions, enabling optimization of the clearance between rotor blades and shroud for maximum efficiency across different operating configurations.
2Manufacturing precision
If piezoelectric actuators are used to adjust shroud position, then clearance control precision is improved, but device complexity increases
Solution Approach 1:
The patent divides the piezoelectric actuator system into multiple independent actuators arranged in two annular rows, with each actuator controlling a specific sector of the shroud. This segmentation allows precise local adjustment of clearance in different regions while maintaining overall system manageability and enabling differential control based on localized clearance measurements.
Solution Approach 2:
The invention transitions from a single-row or linear actuator arrangement to a two-dimensional annular configuration with actuators distributed in two concentric rows. This spatial arrangement provides redundant control pathways and enables more sophisticated clearance profiles around the annular groove, enhancing precision while distributing complexity across multiple locations.
3Productivity
If the shroud is made movable to adapt clearance, then sealing efficiency improves, but structural stability may be compromised
Solution Approach 1:
The patent employs a thin, flexible shroud that can radially move to adapt clearance while maintaining its structural integrity. The shroud's flexibility allows it to respond to piezoelectric actuation forces, enabling efficient clearance adjustment without requiring massive structural changes that would compromise stability.
Solution Approach 2:
The invention incorporates an insulating layer positioned between the piezoelectric actuators and the shroud, serving as both electrical insulation and mechanical cushioning. This layer protects the actuators from thermal and mechanical stresses while allowing the shroud to move freely in response to actuator commands, maintaining both efficiency and stability.
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 enables precise control of clearance between the shroud and rotor blades, enhancing turbomachine efficiency and safety by rapidly responding to changing conditions, while providing radial reinforcement and protecting sensitive components.
Implementation Method 1
The connecting elements are piezoelectric actuators configured to move and/or deform the shroud in order to modify the clearance between the shroud and the rotor blades
Data Source
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Figure 3~4
AI summary
The invention relates to an external casing (28) for an axial turbomachine compressor. The casing (28) includes a sealing device (34) cooperating with a row of rotor blades (24). The casing (28) comprises a wall (30) with an annular groove (38) in which the sealing device (34) is housed. The sealing device comprises a segmented outer shell (36) and a plurality of piezoelectric actuators (46) that radially move the shell (36) within the groove (38) to open or close the functional clearance. The invention also provides a method for controlling a sealing device (34) for a turbojet engine, the method comprising an altitude measurement step and a clearance adjustment step based on altitude.