Turbine Tip Clearance Calculation via Shell-to-Shell Distance
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Solution Overview
Problem
Conventional measurement systems for tip clearance in turbine engines are costly and have short lifespans due to exposure to extreme temperatures, requiring cooling air that reduces engine efficiency and increases maintenance complexity.
Innovation Solution
A method that calculates tip clearance by measuring cold dimensions and temperature changes in a combustion turbine engine, using proximity sensors outside the hot-gas path to measure shell-to-shell distance, thereby reducing the need for sensors in the hot-gas path and minimizing cooling air usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If proximity sensors are positioned in the hot-gas path to directly measure tip clearance, then measurement accuracy is improved, but sensor lifespan decreases and cooling air requirements increase
Solution Approach 1:
The patent uses shell-to-shell distance measurements as an intermediary parameter to indirectly determine tip clearance. Instead of placing sensors directly in the hot-gas path near blade tips, the system measures the distance between stationary shell components and uses thermal growth calculations to derive the actual tip clearance, thereby protecting sensors from extreme temperatures while maintaining measurement accuracy
Solution Approach 2:
The patent replaces direct mechanical/optical measurement systems in the hot-gas path with a calculation-based system. By measuring shell-to-shell distances with proximity sensors in cooler regions and combining these measurements with thermal growth models, the system substitutes direct high-temperature measurement with indirect measurement and computational analysis
2Measurement precision
If proximity sensors are positioned in the hot-gas path, then tip clearance measurement capability is improved, but cooling air requirements increase reducing engine efficiency
Solution Approach 1:
The system uses shell-to-shell distance measurements as an intermediary to avoid direct hot-gas path measurement. By measuring distances between stationary shell components located in cooler regions and using thermal growth calculations, the system eliminates the need for cooling air to protect sensors in the hot-gas path, thereby maintaining engine efficiency
3Measurement precision
If conventional direct measurement systems are used in the hot-gas path, then tip clearance data is obtained, but device complexity and maintenance requirements increase
Solution Approach 1:
The patent employs shell-to-shell distance measurements as an intermediary approach that simplifies the overall system. By measuring distances between stationary shell components rather than directly measuring blade tip positions in the hot-gas path, the system reduces sensor protection requirements and eliminates complex cooling infrastructure, thereby reducing device complexity and maintenance burden
Solution Approach 2:
The patent extracts the measurement function from the hot-gas path environment and relocates it to cooler regions. By measuring shell-to-shell distances in regions away from the extreme hot-gas path conditions and using computational methods to derive tip clearance, the system removes sensors from the harsh environment, significantly reducing maintenance requirements
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 provides accurate and cost-effective tip clearance monitoring, extending sensor lifespan and reducing operational complexity while maintaining engine efficiency.
Implementation Method 1
measuring a shell-to-shell distance with a proximity sensor
Implementation Method 2
calculating a tip clearance based on the cold tip clearance measurement and the plurality of temperature measurements
Data Source
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AI summary
A method of calculating the tip clearance during operation of a combustion turbine engine 10 that includes the steps of: measuring a cold tip clearance and a cold shell-to-shell distance; while the combustion turbine engine 10 is operating, measuring an operating parameter and measuring a shell-to-shell distance with a proximity sensor 22; calculating the tip clearance based on the cold tip clearance measurement and the operating parameter measurement; calculating the shell-to-shell distance based on the cold shell-to-shell distance measurement and the operating parameter measurement; comparing the shell-to-shell distance measurement of the proximity sensor 22 with the shell-to-shell distance calculation; and calibrating the calculated tip clearance calculation based on the comparison.