Gas Turbine Stator Temperature Control via Bottom Casing Preheating
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Solution Overview
Problem
Gas turbine engines face issues with high cycle fatigue, low cycle fatigue, and thermal bowing due to large thermal gradients, leading to reduced structural life and increased operating costs, as well as efficiency and performance degradation.
Innovation Solution
A stator temperature control system that includes a casing with a heat shield and a supply line to direct air from an air source to the bottom portion of the casing, preheating it to maintain temperature uniformity with the top portion, thereby reducing thermal bowing and mitigating fatigue issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If thermal gradients are increased to improve turbine engine performance, then aero- and thermodynamic performance is improved, but structural life is reduced due to high cycle fatigue and low cycle fatigue
Solution Approach 1:
The patent applies local quality by directing heated air specifically to the bottom portion of the casing where thermal gradients cause excessive cooling. This localized heating approach addresses the specific thermal imbalance problem without requiring system-wide temperature changes, thereby maintaining overall engine performance while protecting structural integrity in the critical bottom casing region.
Solution Approach 2:
The system performs preliminary anti-action by preheating the bottom casing portion before thermal bowing and fatigue damage can occur. The control system activates the heating when thermal imbalance is detected, preventing the development of excessive thermal gradients that would lead to structural degradation, rather than addressing damage after it occurs.
2Productivity
If thermal gradients are increased to improve turbine engine performance, then aero- and thermodynamic performance is improved, but component reliability is reduced due to thermal bowing
Solution Approach 1:
The patent implements local quality by applying heat specifically to the bottom portion of the casing where asymmetric cooling creates thermal bowing. This targeted approach corrects the local thermal imbalance that causes stator bowing without requiring uniform heating throughout the entire casing, thus maintaining engine performance while improving component reliability.
Solution Approach 2:
The system changes the temperature parameter locally in the bottom casing region by introducing heated air through the supply line. This parameter change counteracts the excessive cooling in that specific area, reducing thermal gradients and preventing thermal bowing of the stator components while maintaining overall engine performance characteristics.
3Device complexity
If asymmetric cooling is allowed to occur after turbine engine shutdown, then shutdown process is simplified, but thermal bowing is induced in rotating and stator components
Solution Approach 1:
The system applies preliminary anti-action during the shutdown phase by activating the heating system to counteract asymmetric cooling as it begins to occur. The control system detects the transition to shutdown mode and initiates heating of the bottom casing portion, preventing thermal bowing from developing during the cooling process rather than requiring complex active cooling systems to maintain uniform temperature.
Solution Approach 2:
The system utilizes self-service by employing the engine's own air source and thermal energy to heat the bottom casing portion during shutdown. The air source provides bleed air that is heated and directed to the affected area, allowing the system to correct its own thermal imbalance without requiring external heating equipment or complex active cooling systems.
4Stability of the object's composition
If heated air is directed to the bottom portion of the casing, then temperature uniformity is improved, but additional energy input is required
Solution Approach 1:
The patent applies blessing in disguise by converting the engine's waste thermal energy into a useful heating function. The air source provides bleed air that would otherwise be wasted, and this air is heated using the engine's own thermal energy to counteract asymmetric cooling in the bottom casing portion, thereby improving temperature uniformity without requiring external energy input.
Solution Approach 2:
The system implements self-service by using the engine's own air source and thermal energy resources to maintain temperature uniformity. The bleed air from the engine is heated and redirected to the bottom casing portion, allowing the system to correct its own thermal imbalance using internally available resources rather than requiring additional external energy input.
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 effectively reduces bowed stator and associated risks like compressor rubs by maintaining temperature alignment between the top and bottom portions of the casing, without adding additional heat to the system, using air that would otherwise be dumped in conventional systems.
Implementation Method 1
the bottom portion of the casing receives a flow of air from the air source via the supply line to increase a temperature of the bottom portion of the casing
Data Source
AI summary
A stator temperature control system for a gas turbine engine is provided. The stator temperature control system includes a casing circumferentially surrounding a stator assembly, the casing having a top portion and a bottom portion; an air source having an inlet and an outlet; and a supply line in fluid communication with the outlet of the air source and the bottom portion of the casing, wherein the bottom portion of the casing receives a flow of air from the air source via the supply line to increase a temperature of the bottom portion of the casing.