Turbomachine Damping Ring Thermal Insulation
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Solution Overview
Problem
Existing turbomachines face efficiency reductions and blade wear due to varying radial clearances caused by thermal expansion differences between rotor and casing components, particularly exacerbated by low-mass damping rings with high thermal inertia, which existing active clearance control devices attempt to address but at the cost of air intake and complex structural modifications.
Innovation Solution
A turbomachine module with a thermal inertia control device featuring a layer of thermal insulation mounted on the damping ring, which harmonizes the expansion speeds of the damping ring with the inner and outer casings by increasing the time required for temperature changes, thereby reducing radial clearance variations without requiring air flow diversion or complex structural additions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If damping rings are made with low mass to reduce turbomachine mass, then turbomachine mass is reduced, but thermal inertia is reduced causing rapid thermal expansion and radial clearance variation
Solution Approach 1:
The patent changes the thermal parameter (thermal inertia) of the damping ring by adding a thermal insulation layer. This allows the ring to maintain low mass while having controlled thermal expansion characteristics, thereby stabilizing radial clearances during operation.
Solution Approach 2:
The damping ring is constructed as a composite structure with a metallic base and a thermal insulation layer (such as ceramic coating or insulating material). This composite design provides both mechanical strength and controlled thermal properties, resolving the contradiction between low mass and thermal stability.
2Stability of the object's composition
If active clearance control devices are used to stabilize radial clearances, then radial clearance stability is improved, but device complexity and structural modifications increase
Solution Approach 1:
The damping ring with thermal insulation layer autonomously controls its own thermal expansion characteristics. The insulation layer naturally delays heat transfer, providing self-regulating thermal expansion without requiring external control systems, sensors, or complex structural modifications.
Solution Approach 2:
The patent extracts the thermal management function from complex active control systems and integrates it directly into the damping ring structure through the thermal insulation layer. This simplifies the overall system by eliminating the need for separate active clearance control devices.
3Stability of the object's composition
If active clearance control devices are used to stabilize radial clearances, then radial clearance stability is improved, but air flow is diverted from the primary flow reducing efficiency
Solution Approach 1:
The thermal insulation layer on the damping ring provides passive thermal management using the existing thermal environment. It utilizes the natural heat transfer processes in the turbomachine without requiring additional air flow diversion, thereby maintaining full efficiency of the primary gas flow.
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 effectively stabilizes radial clearances, enhancing turbomachine efficiency and reducing blade wear by synchronizing the response times and displacement amplitudes of the internal casing relative to the rotor, without penalizing mass or efficiency.
Implementation Method 1
the device for controlling the thermal inertia comprising at least one layer of thermal insulation
Implementation Method 2
increase the time necessary for the damping ring to change temperature
Implementation Method 3
harmonize the speed of expansion of the damping ring with those the inner casing and the outer casing
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
The module has an external casing, and an internal casing crossed by a primary flow of turbomachine. A damping ring (5) connects the casings. An annular cavity (43) is provided towards a downstream with respect to the ring and includes an axial clearance (42) i.e. passage, for ensuring removal of air flow (4) from the primary flow. Radial clearance improving device has a control device mounted on the ring for controlling thermal inertia of the ring. The control device includes a heat insulation layer (8) made of glass fiber and silica wool felt, and forms the cavity in downstream of the layer.