Turbine Case Cooling via Predictive Thermal Expansion Control
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Solution Overview
Problem
Current turbine case cooling methods in gas turbine engines lack precision in maintaining a consistent gap between turbine blades and the inner casing due to the harsh environment, making it difficult to use sensors for real-time feedback, leading to conservative cooling and potential efficiency losses.
Innovation Solution
A model-based predictive control system that monitors the engine's state by measuring turbine gas temperature and predicts the thermal expansion of the turbine case and blades, adjusting cooling air supply to maintain a consistent gap between the turbine case and blades over time, without the need for additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are used to measure the gap between turbine blades and casing, then measurement precision is improved, but device complexity and weight increase
Solution Approach 1:
The patent creates a virtual copy of the physical sensor system through software-based simulation. A mathematical model replicates the thermal expansion behavior of turbine blades and casing, generating virtual gap measurements without physical sensors. This software model processes engine operating parameters (temperature, pressure, speed) to predict blade-casing gaps, eliminating the need for harsh-environment sensors while maintaining measurement capability.
Solution Approach 2:
The patent replaces the mechanical sensor system with a computational model. Instead of using physical sensors that mechanically measure the gap in the harsh turbine environment, the system uses a software-based thermal expansion model that calculates gap dimensions based on thermodynamic parameters. This substitution eliminates mechanical components from the measurement system, reducing complexity and avoiding sensor failure in high-temperature environments.
2Reliability
If conservative cooling is used to avoid blade rubbing, then reliability is improved, but engine efficiency deteriorates
Solution Approach 1:
The patent implements a closed-loop feedback system where the software model continuously monitors predicted gap dimensions and adjusts cooling air flow accordingly. The model processes real-time engine operating parameters, predicts thermal expansion, and provides feedback signals to cooling control valves. This feedback mechanism allows dynamic optimization of cooling, preventing blade rubbing while minimizing unnecessary cooling air consumption that would otherwise reduce engine efficiency.
Solution Approach 2:
The patent transitions from static conservative cooling to dynamic adaptive cooling. The software model continuously updates gap predictions based on changing engine operating conditions (temperature, pressure, speed variations). Cooling air flow is dynamically adjusted in real-time to match actual thermal expansion needs, rather than maintaining constant conservative cooling. This dynamic approach optimizes the balance between reliability and efficiency across varying operating regimes.
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 by maintaining a consistent gap, reducing the risk of blade rubbing and avoiding the need for extra weight and complexity from additional sensors, while optimizing cooling based on future thermal expansion predictions.
Implementation Method 1
turbine case cooling is often provided to force cool air between the outer and inner skins of the turbine casing to reduce expansion of the inner skin
Implementation Method 2
As the core engine temperature rises, the inner skin will generally expand at a faster rate than the turbine blade
Data Source
AI summary
A method of controlling turbine case cooling in a gas turbine engine, the method including monitoring the present state of the engine 32 and using a predictive model based system 44, 46 to predict the future thermal expansion of the turbine case 12 and turbine blades 28, and controlling cooling of the turbine case 12 in response to said prediction to provide a required gap 30 over time.