Gas Turbine Active Clearance Control via Plenum Impingement
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Solution Overview
Problem
Existing gas turbine engine clearance control systems fail to effectively manage the clearance between structural members and blades, leading to inefficiencies in fluid flow and blade tip wear, as they rely on passive methods that do not allow for precise temperature control of structural members.
Innovation Solution
An active clearance control system that includes a plenum arranged over the joint between structural members, with a valve and controller system to selectively provide temperature conditioning fluid, using fan air or rear hub air, to control the clearance by thermally conditioning the structural members through impingement holes, allowing for precise adjustment of clearance based on sensor data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If passive clearance control methods (heat shield or cooling fluid through impingement holes) are used, then clearance control is provided, but precise temperature control of structural members is not achieved
Solution Approach 1:
The system transitions from passive static clearance control to active dynamic control by continuously monitoring structural member temperature with sensors and adjusting heating element power accordingly. This dynamic feedback system enables precise temperature control that adapts to changing operating conditions, resolving the contradiction between control precision and system complexity.
Solution Approach 2:
Temperature sensors provide real-time feedback on structural member temperature to a control system, which then adjusts the heating elements to maintain optimal temperature ranges. This closed-loop feedback mechanism achieves precise clearance control while managing system complexity through intelligent control algorithms.
2Temperature
If cooling fluid is supplied to impingement holes on the back side of the blade outer air seal, then cooling is provided, but cooling fluid enters the blade flow path which is undesired
Solution Approach 1:
The invention extracts the cooling function from the blade outer air seal structure and relocates it to a separate plenum chamber positioned adjacent to the structural member joint. This separation allows cooling fluid to be applied directly to the structural member without risking contamination of the blade flow path, as the cooling system is physically isolated from the aerodynamic flow path.
Solution Approach 2:
The plenum chamber acts as an intermediary structure that enables thermal management of the structural member without direct fluid interaction with the blade assembly. The plenum receives heating elements and contains the thermal management fluid, serving as a mediator between the heating/cooling system and the structural member, while preventing fluid contamination of the blade flow path.
3Manufacturing precision
If active clearance control with plenum and heating elements is implemented, then precise temperature control is achieved, but device complexity increases
Solution Approach 1:
The plenum chamber serves multiple functions: it contains heating elements for thermal management, provides structural support, and acts as a mounting platform for temperature sensors. By consolidating these functions into a single multi-functional component, the system achieves precise clearance control while minimizing the increase in overall device complexity.
Solution Approach 2:
The invention merges the plenum chamber with the structural member assembly, integrating the thermal management system into the existing structural framework rather than adding completely separate components. This integration reduces overall system complexity while maintaining precise active clearance control capabilities through coordinated heating and sensing.
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 system enables precise control of clearance between structural members and blades, improving fluid flow efficiency and reducing blade tip wear by actively managing thermal expansion, thereby enhancing the operational performance of gas turbine engines.
Implementation Method 1
control the clearance between the case and a blade tip of the blade by thermally conditioning the structural member
Implementation Method 2
provide temperature conditioning fluid... to control the temperature of the structural member
Data Source
Figure 1
Figure 2~4
AI summary
An active clearance control system for a gas turbine engine includes a structural member that is configured to be arranged near a blade tip. A plenum includes first and second walls respectively providing first and second cavities. The first wall includes impingement holes. The plenum is arranged over the structural member. A fluid source is fluidly connected to the second cavity to provide an impingement cooling flow from the second cavity through the impingement holes to the first cavity onto the structural member. A method includes the steps of providing a conditioning fluid to an outer cavity of a plenum providing an impingement cooling flow through impingement holes from an inner wall of the plenum to an inner cavity, directing the impingement cooling flow onto a structural member, and conditioning a temperature of the structural member with the impingement cooling flow to control a blade tip clearance.