Composite Turbine Rotor Wheel Spring Ring Sealing
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Solution Overview
Problem
Turbomachine rotor wheels with composite material blades experience significant thermal expansion differences with metal casings, leading to incomplete closure of radial clearance and inadequate sealing due to labyrinth teeth and abradable material, resulting in gas leakage.
Innovation Solution
A rotor wheel design featuring an annular mounting plate with composite material blades, an orientation disk with axial slots, and a variable-diameter spring ring that radially abuts an inside surface of the orientation disk, ensuring proper sealing by eliminating radial clearance between labyrinth teeth and abradable material under centrifugal force and thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If radial clearance is left between blade tips and casing during cold assembly, then ease of assembly is improved, but sealing performance deteriorates during hot operation due to incomplete clearance closure
Solution Approach 1:
The blade assembly system transitions from a static clearance configuration to a dynamic one where the spring ring actively adjusts the blade radial position in response to thermal and centrifugal loads. During cold assembly, blades maintain clearance for easy installation; during hot operation, the spring ring enables dynamic radial movement to close the clearance and maintain sealing performance.
Solution Approach 2:
The system exploits changes in physical parameters (thermal expansion and centrifugal force) to transform the radial clearance state. The spring ring converts thermal expansion and centrifugal effects into beneficial radial blade movement that closes the clearance during operation, turning parameter changes that could cause problems into the mechanism that solves the sealing issue.
2Weight of moving object
If composite material blades are used, then weight is reduced, but sealing performance deteriorates due to differential thermal expansion with metal casing
Solution Approach 1:
The spring ring acts as an intermediary element between the composite blades and the metal mounting plate. It mediates the differential thermal expansion and centrifugal effects by allowing relative movement and converting these effects into beneficial radial blade displacement that maintains sealing, rather than allowing direct stress transmission that would compromise sealing performance.
Solution Approach 2:
The invention directly utilizes thermal expansion of the spring ring and differential thermal expansion between composite blades and metal mounting plate. Instead of treating thermal expansion as a problem to be eliminated, the design harnesses it to drive the radial movement of blades that closes the clearance and maintains sealing during hot operation.
3Reliability
If spring ring is added to enable radial blade movement, then sealing performance is improved, but device complexity increases
Solution Approach 1:
The spring ring functions as a flexible elastic element that enables controlled deformation and movement. This flexible component allows the rigid blade assembly to dynamically adjust its radial position in response to thermal and centrifugal loads, providing the necessary movement to close clearances without requiring complex actuation mechanisms.
Solution Approach 2:
The spring ring creates a self-regulating system where the blade assembly automatically adjusts its own radial position in response to operating conditions. The elastic element converts thermal expansion and centrifugal forces into the necessary radial movement to maintain sealing, eliminating the need for external control systems or additional actuators.
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 design effectively ensures sealing between the rotor wheel and casing during operation by utilizing the spring ring's thermal and centrifugal expansion to maintain radial abutment, reducing gas leakage and maintaining structural integrity.
Implementation Method 1
The spring ring may be made of a material that is suitable for expanding thermally so that its diameter varies as a function of the temperature to which it is subjected.
Implementation Method 2
the spring ring may also be split such that its diameter varies when it is subjected to centrifugal force
Implementation Method 3
In operation, under the effect of the centrifugal force exerted by the wheel, the blades move radially outwards relative to the mounting plate, taking the spring ring with them
Implementation Method 4
the free ends of the blades are generally provided with radial labyrinth teeth, and an abradable material is mounted on the inside surface of the casing in register with the labyrinth teeth. In operation of the rotor wheel, the disk, the blades, and the casing surrounding the wheel expand so that the labyrinth teeth carried by the blades abrade the abradable material carried by the casing
Data Source
AI summary
A turbomachine rotor wheel including blades made of composite material; an annular mounting plate; a plurality of composite material blades mounted on the mounting plate, each blade also including a top platform at its tip carrying radial labyrinth teeth; an orientation disk fastened coaxially around the mounting plate and including at its outer periphery a plurality of axial slots that are open at one end, each slot presenting a cross-section that matches the cross-section of a blade root so as to hold it angularly in position by co-operation of shapes; and a variable-diameter spring ring housed in part in an axial notch formed in each blade root and projecting axially relative thereto, the spring ring to come into radial abutment against an inside surface of the orientation disk during radial outward movement of the blades relative to the mounting plate.