Turbine Shroud Buffer Chamber Cooling and Health Monitoring
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Solution Overview
Problem
The integration of components with different coefficients of thermal expansion in turbine shrouds poses challenges for assembly and operation due to differential expansion rates under high temperatures, leading to potential burn-through issues and performance losses.
Innovation Solution
An annular turbine shroud with a buffer chamber that receives cooling air, coupled with a health monitoring system using pressure sensors and a valve control system to modulate cooling air flow, ensuring uniform temperature distribution and detecting burn-through conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If components with different coefficients of thermal expansion are integrated in turbine shrouds, then the shroud can be made from diverse materials to withstand high temperatures, but differential expansion rates cause assembly and operation challenges
Solution Approach 1:
The turbine shroud is divided into multiple segments that can expand and contract independently. Each segment is made from materials with different coefficients of thermal expansion, allowing them to withstand high temperatures while minimizing differential expansion issues through independent movement.
Solution Approach 2:
The design incorporates adjustable parameters such as segment geometry, material selection, and expansion clearance to accommodate differential thermal expansion. By changing these parameters, the system can adapt to varying temperature conditions while maintaining proper assembly and operation.
2Measurement precision
If traditional temperature monitoring methods are used, then local temperature points can be measured, but comprehensive health monitoring of the entire shroud is insufficient
Solution Approach 1:
The health monitoring system uses universal sensors that can detect multiple parameters (temperature, strain, vibration) across the entire shroud structure. This multi-functional approach provides comprehensive health monitoring without requiring separate specialized systems for each parameter or location.
Solution Approach 2:
The system employs intermediary sensors embedded within the shroud structure that mediate between the physical conditions (temperature, stress) and the monitoring system. These sensors provide indirect measurement of shroud health, enabling comprehensive monitoring while keeping the overall system complexity manageable.
3Temperature
If cooling air is not directed into the buffer chamber, then the system is simpler, but the turbine shroud cannot maintain uniform temperature distribution under high temperature exposure
Solution Approach 1:
Cooling air is directed into the buffer chamber before the turbine shroud components reach critical temperatures. This preliminary cooling action prevents excessive temperature differentials and maintains uniform temperature distribution across the shroud, avoiding the need for more complex active temperature control systems.
Solution Approach 2:
The system uses pneumatic cooling by directing compressed cooling air through the buffer chamber. This approach maintains uniform temperature distribution through fluid dynamics principles, providing effective cooling while keeping the system relatively simple compared to mechanical or electronic temperature control alternatives.
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 solution maintains uniform radial expansion of the shroud components, prevents performance losses by blocking combustion products effectively, and enables reliable health monitoring and adaptive cooling to prevent damage.
Implementation Method 1
The buffer chamber is configured to receive cooling air to control a temperature of the turbine shroud
Implementation Method 2
The health monitoring system illustratively includes one (or a few) pressure sensor(s) configured to measure an air pressure in the buffer chamber
Implementation Method 3
Due to the differing coefficients of thermal expansion, the components of some turbine shrouds expand at different rates when exposed to combustion products
Data Source
AI summary
A gas turbine engine includes a turbine having a plurality of vanes, a plurality of blades, a turbine shroud arranged around the vanes and blades, and a turbine case arranged around the turbine shroud. The turbine shroud is sized to block combustion products from passing over the blades without pushing the blades to rotate. The turbine shroud includes a runner arranged around the blades and a carrier arranged around the runner.