Turbine Vane Assembly Position Retaining Device
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Solution Overview
Problem
The integration of ceramic matrix composite (CMC) materials within turbine engine nozzles is challenging due to differences in thermal expansion with metal environments, requiring a device to facilitate and retain CMC parts effectively.
Innovation Solution
A position retaining device is used, comprising elastically prestressed curved metal sheets between the inner shroud and vane assembly, applying stress to maintain the vane assembly flat against the outer shroud while limiting forces, allowing for secure positioning without significant structural changes to the nozzle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If CMC materials are integrated within metal environment in turbine nozzles, then high-temperature mechanical properties and lightweight characteristics are improved, but differences in thermal expansion cause integration difficulties and positioning issues
Solution Approach 1:
The patent introduces a positioning device as an intermediary component between the CMC vane assembly and metal nozzles. This positioning device accommodates thermal expansion differences by allowing relative movement or deformation, preventing direct stress transmission that would cause integration failures. The intermediary layer resolves the incompatibility between CMC and metal thermal expansion characteristics.
Solution Approach 2:
The positioning device is designed to change its physical parameters (such as shape, volume, or stiffness) in response to temperature variations. By allowing the positioning device to deform or expand with temperature changes, the system accommodates thermal expansion differences without compromising the structural integrity of either the CMC vane assembly or metal nozzles.
2Reliability
If a positioning device is added to retain CMC parts, then positioning accuracy and integration reliability are improved, but device structure becomes more complex
Solution Approach 1:
The positioning device is segmented into multiple independent components or functional zones, each handling specific aspects of positioning or thermal accommodation. This segmentation allows each component to be optimized independently and simplifies the overall structure by distributing functions across multiple smaller elements rather than requiring a single complex device.
Solution Approach 2:
The positioning device is designed to automatically adjust and maintain proper positioning without requiring external control systems or complex actuation mechanisms. The device self-regulates its positioning function in response to thermal expansion, vibration, or other operational conditions, thereby achieving high reliability through simple, passive mechanisms.
3Reliability
If elastically prestressed position retaining device is used between inner shroud and vane assembly, then vane assembly is held securely against outer shroud, but forces within position retaining device increase
Solution Approach 1:
The position retaining device uses elastic prestressing to create a dynamic system that can adapt to varying operational conditions. The elastic components allow the device to flex and redistribute forces in response to thermal expansion, vibration, or load changes, maintaining secure holding while preventing excessive force concentration that would lead to failure.
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
This solution ensures the secure holding of the vane assembly at various operating phases with minimal risk of damage, facilitating integration and reducing risks of structural damage, while maintaining the lightweight and high-temperature mechanical properties of CMC materials.
Implementation Method 1
a position retaining device configured to be placed in an elastically prestressed state between the inner shroud and an inner platform of the vane assembly, so as to apply a stress on the vane assembly that is oriented towards the outer shroud
Data Source
AI summary
A turbine engine nozzle extending about an axis and including a vane assembly mounted between an outer shroud and an inner shroud; and a position retaining device configured to be placed in an elastically prestressed state between the inner shroud and an inner platform of the vane assembly to apply a stress on the vane assembly towards the outer shroud. The contact between the inner shroud and the inner platform is obtained by one same surface of the position retaining device.