Actuation Ring Tip Clearance Control for Gas Turbine
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Solution Overview
Problem
Gas turbine engines face inefficiencies due to large tip clearance between blade tips and the blade outer air seal (BOAS) caused by rapid expansion of blade tips relative to the engine case, necessitating active control systems to manage this clearance effectively.
Innovation Solution
An actuation ring system with an actuator that can adjust the circumference of the actuation ring radially inward or outward, coupled with radial guides and a compressible feature to maintain symmetry and alignment, allowing for precise control of tip clearance between blade tips and BOAS, using various actuation mechanisms such as threaded, cam, or gear actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the tip clearance is designed to be relatively large to accommodate rapid blade tip expansion, then the blade tips can expand outward without excessive stress, but the engine efficiency deteriorates due to increased clearance between blade tips and BOAS
Solution Approach 1:
The actuation ring is designed to be radially movable relative to the engine case, allowing the BOAS to dynamically adjust its position in response to blade tip expansion. This dynamic adjustment maintains optimal tip clearance under varying operating conditions, resolving the contradiction between accommodating thermal expansion and maintaining engine efficiency.
Solution Approach 2:
The system incorporates sensors that detect blade tip position and BOAS position, providing feedback to a controller that actuates the actuation ring to maintain optimal clearance. This closed-loop feedback mechanism ensures the clearance adapts to thermal expansion while maintaining efficiency.
2Productivity
If an active tip clearance control system is implemented to reduce clearance and improve efficiency, then engine efficiency improves, but the device complexity increases due to additional actuators and control mechanisms
Solution Approach 1:
The actuation ring serves multiple functions: it positions the BOAS relative to the engine case, maintains radial alignment through symmetric design, and accommodates thermal expansion. This multi-functionality reduces the need for separate components, thereby limiting the increase in device complexity while achieving active clearance control.
Solution Approach 2:
The actuation ring incorporates asymmetric thickness distribution (thinner at the gap, thicker at the distal location) to compensate for non-uniform thermal expansion and maintain radial symmetry during actuation. This asymmetric design allows the system to handle complex thermal conditions without requiring equally complex control mechanisms.
3Ease of operation
If the actuation ring is made thinner at the gap location to enable radial movement, then the radial adjustment capability improves, but the structural strength deteriorates
Solution Approach 1:
The actuation ring features non-uniform thickness with a thinner section at the gap location to facilitate radial movement and a thicker section at the distal location to provide structural strength. This local variation in geometry optimizes both movement capability and structural integrity, resolving the contradiction between ease of operation and strength.
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
Enables quick and precise adjustment of tip clearance to maintain engine efficiency, reduce thermal loads, and extend component life by actively managing the clearance between blade tips and BOAS, with radial movement capabilities and rapid response times.
Implementation Method 1
the blade tips can expand outward due to increased heat and centrifugal force at a faster rate than the case expands outward
Implementation Method 2
a compressible feature positioned between the actuation ring and the actuator to counteract distortion of the actuation ring
Implementation Method 3
the blade tips can expand outward due to increased heat and centrifugal force at a faster rate than the case expands outward
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
An actuation system (200) for tip clearance control of gas turbine engines can include an actuation ring (202) having a first end (205) and a second end (207) separated by a gap (203), the actuation ring (202) being configured to be coupled to a blade outer air seal (BOAS) (302). The actuation system (200) can also include an actuator (204) coupled to at least one of the first end (205) or the second end (207) and configured to adjust a size of the gap (203) such that a tip clearance between the BOAS (302) and a blade tip (420) is reduced in response to the size of the gap (203) being reduced.