Active Clearance Valves for Precise Turbine Blade Tip Control
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Solution Overview
Problem
Conventional gas turbine engines face challenges in maintaining optimal blade tip clearance due to thermal and mechanical expansion and contraction, leading to inefficiencies and potential damage from unintended contact between rotating blades and stationary components.
Innovation Solution
The implementation of active clearance control (ACC) systems using linearly controlled valves to manage airflow rates for precise thermal expansion control, minimizing reliance on engine operating conditions and reducing turbulence, thereby optimizing blade tip clearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional passive clearance control is used, then device complexity is reduced, but blade tip clearance control precision deteriorates due to thermal and mechanical expansion
Solution Approach 1:
The patent applies parameter changes by actively adjusting the thermal state of the engine casing through controlled airflow. The ACC system modifies temperature parameters of the casing to compensate for thermal expansion, thereby maintaining precise blade tip clearance. This involves changing the thermal parameters of the system dynamically rather than relying on passive geometric design.
Solution Approach 2:
The patent replaces traditional mechanical clearance control mechanisms with a thermal-based active control system. Instead of using mechanical adjusters or shims to control clearance, the system uses controlled thermal expansion/contraction of the casing through regulated airflow, substituting mechanical adjustment with thermal field control.
2Stability of the object's composition
If active clearance control systems are implemented, then blade tip clearance stability is improved, but device complexity increases due to additional valves and control mechanisms
Solution Approach 1:
The patent segments the airflow control into multiple independent valves (inlet valve, mid-pipe valve, outlet valve) that can be controlled separately. This segmentation allows precise control of airflow at different stages, enabling stable clearance control while making the complex system more manageable through modular valve components.
Solution Approach 2:
The patent introduces intermediate components such as the mid-pipe valve and manifold structures that act as mediators between the airflow source and the engine casing. These intermediary elements provide additional control points and allow for more gradual, precise adjustment of the thermal field, improving stability while distributing system complexity across multiple manageable components.
3Manufacturing precision
If airflow rate is increased for thermal expansion control, then blade tip clearance control is improved, but turbulence increases leading to energy loss
Solution Approach 1:
The patent employs periodic or pulsed airflow action rather than continuous high-velocity flow. By using controlled intermittent airflow through the valves, the system achieves the necessary thermal effect for clearance control while reducing continuous turbulence and associated energy losses. This allows precise clearance control with reduced energy expenditure.
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 approach enhances engine efficiency and reduces specific fuel consumption by maintaining consistent blade tip clearance, minimizing wear, and preventing unintended contact.
Implementation Method 1
the gas turbine engine is exposed to thermal (e.g., hot and cold air pumped into the gas turbine engine, etc.) and mechanical loads (e.g., centrifugal force on the blades on the gas turbine engine, etc.), which can expand and contract the gas turbine engine casing and rotor
Data Source
AI summary
Active clearance control valves and related methods are disclosed. An example apparatus includes a pipe defining a flow path between (i) at least one of a fan section, a bypass airflow passage, or a compressor section and (ii) a turbine section of the gas turbine, the pipe including an inlet fluidly coupled to at least one of the fan section, the bypass airflow passage, or the compressor section, a valve coupled to the pipe and positioned downstream of the inlet, the valve including swing wings, the swing wings positioned around an opening in the pipe defined by the second valve when the second valve is at least partially open.