Gas Turbine Blade Tip Clearance Actuation
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Solution Overview
Problem
Existing gas turbine engines face inefficiencies due to the mismatched thermal responses of the rotor and casing, leading to suboptimal blade tip clearance during transient and steady-state operations, resulting in reduced compressor efficiency and potential seal rub-outs.
Innovation Solution
A running clearance system that utilizes a mechanical actuator to rapidly adjust the blade tip clearance by axially moving the rotor assembly relative to the shroud, allowing for selective adjustment of the clearance distance between the blade tips and the shroud seal surfaces, independent of thermal expansion or contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If prior art active clearance systems utilize thermal expansion or contraction of the casing to adjust clearance, then the clearance can be adjusted, but the response time is slow due to the casing's thermal response time
Solution Approach 1:
The patent replaces the thermal field system (heating/cooling air to cause thermal expansion/contraction) with a mechanical field system (direct mechanical actuation of the casing via actuators). This substitution eliminates the slow thermal response time while achieving fast mechanical adjustment of the casing position relative to the rotor, thereby resolving the contradiction between adjustable clearance and slow response time.
2Productivity
If the clearance is minimized at worst-case conditions, then the minimum design clearance is reduced, but the clearance is suboptimal under normal operating conditions
Solution Approach 1:
The patent implements a dynamic clearance control system where the casing position is actively adjusted in real-time based on operating conditions. Unlike static clearance designs optimized for worst-case scenarios, this system continuously adapts the clearance to maintain optimal values across varying operating conditions, thereby improving compressor efficiency without sacrificing adaptability.
Solution Approach 2:
The system employs feedback control by monitoring operating conditions and adjusting the casing position accordingly. Sensors detect parameters such as rotor position and operating state, and the control system responds by actuating the casing to maintain optimal clearance, enabling the system to adapt to changing conditions and maintain high efficiency across the operating range.
3Reliability
If abradable seals are used to maintain blade tip clearance, then the clearance can be maintained, but the system is not adjustable once the seal is abraded
Solution Approach 1:
The patent replaces the passive abradable seal mechanism with an active mechanical adjustment system. Instead of relying on material wear to maintain clearance, the system uses actuators to mechanically adjust the casing position, providing both reliable clearance maintenance and full adjustability throughout the component life cycle.
Data Source
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AI summary
A zero running clearance system for gas turbine engines includes a gas turbine engine compressor (14) having one or more first rotor assemblies (30) and one or more first stator assemblies (28) disposed adjacent the one or more first rotor assemblies (30); a gas turbine engine turbine (18) having one or more second rotor assemblies (104) and one or more second stator assemblies (102) disposed adjacent the one or more second rotor assemblies (104); one or more shroud segments (80) having blade seal surfaces (120) disposed radially outside of the tips of blades of both the first and second rotor assemblies (30;104) and a clearance distance extending between the blade tips and blade seal surfaces; and, an actuator (58) selectively operable to axially move the first and said second rotor assemblies (30;104) to alter the clearance distance.