Turbine Nozzle Cooling Subsystem Diffuser Channeling
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Solution Overview
Problem
Combustion turbine engines face efficiency decreases and increased NOx formation due to the introduction of cooling air into the gas stream, which reduces engine flexibility and power output, while also being limited by high combustion gas temperatures and narrow fuel/air ratios.
Innovation Solution
A turbine nozzle cooling sub-system with an arcuate radially outermost and innermost endwall, airfoil vanes, and turbulators, coupled with a diffuser that channels a portion of the compressor discharge air stream to the nozzle segment, facilitating airfoil cooling and minimizing the introduction of cooling air into the gas stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cooling air is introduced into the combustion gas stream via film cooling of turbine nozzle vanes, then the temperature of the nozzle vanes is reduced and component life is extended, but the temperature of the combustion gas stream is reduced which decreases turbine assembly power output and engine efficiency
Solution Approach 1:
The patent applies local quality by providing different cooling strategies to different parts of the system. The turbine nozzle vanes receive film cooling to protect them from high temperatures, while the combustion gas stream is minimized in cooling air introduction to maintain its temperature and power output. This localized differentiation allows each component to be cooled appropriately without compromising overall system performance.
Solution Approach 2:
The patent uses an intermediary approach by introducing cooling air through a dedicated cooling passage that separates the cooling function from the gas stream flow. The cooling air is channeled through the nozzle vane cavity and exits through the trailing edge, acting as an intermediary that protects the vane without significantly mixing with the combustion gas stream, thus maintaining both cooling effectiveness and gas stream temperature.
2Reliability
If cooling air is introduced into the combustion gas stream, then the nozzle vanes are cooled, but the fuel/air ratio increases which increases NOx formation
Solution Approach 1:
The patent extracts the cooling air from the combustion gas stream by providing a separate cooling passage that draws cooling air from the compressor discharge and directs it through the nozzle vane cavity. This separation ensures that cooling air does not mix with the combustion gases, thereby maintaining the fuel/air ratio and preventing increased NOx formation while still achieving effective nozzle vane cooling.
Solution Approach 2:
The cooling passage acts as an intermediary that separates the cooling air flow from the combustion gas stream. By channeling cooling air through a dedicated path with openings in the endwalls and cavity, the system achieves cooling without allowing cooling air to mix with combustion gases, thus maintaining the original fuel/air ratio and preventing NOx formation.
3Productivity
If the rate of combustion is increased to restore combustion gas stream temperature, then the temperature and power output are restored, but the rate of combustion increases which increases NOx formation
Solution Approach 1:
The cooling passage serves as an intermediary that allows cooling air to be introduced without affecting the combustion gas stream temperature. By separating the cooling function from the combustion process, the system maintains optimal combustion temperatures and fuel/air ratios, preventing the need to increase combustion rate and thereby avoiding increased NOx formation.
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 solution mitigates the decrease in engine efficiency, reduces NOx formation, and maintains a stable fuel/air ratio, thereby improving the operational flexibility and reducing maintenance costs by enhancing the cooling efficiency and reducing the temperature decrease caused by film cooling.
Implementation Method 1
Cooler air entering the gas stream via the nozzle vane cavities is disposed to the radially outwardmost section of the nozzle, i.e., the outer surface of the vane, and induces a film cooling effect by forming a layer of cooler air along the outer walls of the vanes
Implementation Method 2
The cavity includes an airfoil vane internal surface and a plurality of turbulators. The cavity and the open passages are in flow communication such that an airfoil cooling air stream flow is facilitated
Data Source
AI summary
A turbine nozzle cooling sub-system is provided. The sub-system includes at least one turbine nozzle segment. The segment includes an arcuate, radially outermost endwall, an arcuate, radially innermost endwall, and at least one airfoil vane. The endwalls each include at least one open passage. The airfoil vane extends between and is coupled to the endwalls. The vane further includes a cavity, a leading edge, a trailing edge, and an airfoil vane external surface. The cavity includes an airfoil vane internal surface and a plurality of turbulators. The cavity and the open passages are in flow communication such that an airfoil cooling air stream flow is facilitated. The sub-system also includes at least one diffuser in flow communication with a compressor assembly and the segment. The diffuser includes at least one diffuser wall and cavity. The diffuser wall extends from the compressor assembly to the segment such that a channeling of the airfoil cooling air stream to the segment is facilitated. The airfoil cooling air stream includes at least a portion of a compressor assembly discharge air stream flow.