Passive Clearance Control for Gas Turbine Efficiency
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Solution Overview
Problem
Existing turbomachines lack an efficient mechanism for autonomously adjusting the clearance between rotor blades and stators to optimize operational efficiency and cooling within the turbine portion without external control systems.
Innovation Solution
A passive clearance control system that includes a sensing cavity with a fluid parameter indicative of the desired operational mode, a passive flow modulating device responsive to these parameters, and cooling channels to adjust the clearance between rotor blades and stators by selectively passing fluid through the turbine casing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a passive clearance control system is implemented, then operational efficiency and cooling are enhanced through autonomous clearance adjustment, but device complexity increases due to additional sensing cavities and flow modulating devices
Solution Approach 1:
The clearance control system operates autonomously using self-service principles. The sensing cavity detects fluid parameters (pressure, temperature) and the passive flow modulating device automatically adjusts cooling fluid flow to modify casing expansion/contraction, thereby controlling rotor blade-to-stator clearance without external intervention. This self-regulating mechanism enhances operational efficiency while maintaining acceptable device complexity through integrated passive control.
Solution Approach 2:
The system utilizes parameter changes in the cooling fluid (pressure, temperature) detected by the sensing cavity to dynamically adjust the thermal state of the turbine casing. By varying the cooling fluid flow rate through the passive flow modulating device, the casing dimensions are modified, which directly controls the clearance between rotor blades and stators, optimizing operational efficiency across different operating conditions.
2Productivity
If cooling fluid flow is increased through the turbine casing, then rotor blade-to-stator clearance is reduced for improved efficiency, but excessive cooling may cause thermal shock or structural stress
Solution Approach 1:
The sensing cavity provides continuous feedback on the thermal state of the turbine casing by monitoring fluid parameters (pressure, temperature). This feedback mechanism enables the passive flow modulating device to dynamically adjust the cooling fluid flow rate, increasing cooling when clearance is excessive and reducing cooling when the casing is sufficiently cooled, thereby preventing thermal shock while maintaining optimal clearance for operational efficiency.
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 system allows for autonomous adjustment of rotor blade-to-stator clearance, enhancing operational efficiency and cooling while maintaining desired operational parameters without external intervention, thereby improving turbomachine performance.
Implementation Method 1
A passive clearance control system includes a valve arranged in the sensing cavity and responsive to pressure and/or temperature of the fluid
Implementation Method 2
The valve selectively passes the cooling fluid from the sensing cavity through a plurality of cooling channels to adjust a thermal state of the turbine shell
Implementation Method 3
The valve selectively passes the cooling fluid from the sensing cavity through a plurality of cooling channels to adjust a thermal state of the turbine shell
Data Source
AI summary
A turbomachine includes a compressor portion, and a turbine portion operatively connected to the compressor portion. The turbine portion includes a turbine casing. A combustor assembly, including at least one combustor, fluidically connects the compressor portion and the turbine portion. At least one of the compressor portion, turbine portion and combustor assembly includes a sensing cavity. A passive clearance control system is operatively arranged in the turbomachine. The passive clearance control system includes at least one passive flow modulating device mounted in the sensing cavity, and at least one cooling channel extending from the sensing cavity through the casing. The at least one passive flow modulating device selectively passes the fluid from the sensing cavity through the at least one cooling channel to adjust a clearance between stators and rotating airfoils in the turbine portion.