Venturi Airflow Control for Gas Turbine Combustor Wake Reduction
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Solution Overview
Problem
Wakes created by flow disturbances in the space between the liner and flow sleeve of a gas turbine combustor lead to fuel accumulation, flame holding, and increased pressure drop, negatively impacting gas turbine performance and potentially causing shutdowns.
Innovation Solution
A venturi is introduced in the air passage to restrict and diffuse airflow, reducing wake formation by using a converging and diverging section with air apertures that introduce higher pressure air to increase velocity and reduce wake recirculation, combined with strategically positioned air apertures to enhance airflow stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a crossfire tube or flame detector is disposed within the space between the liner and flow sleeve, then flame detection or crossfire functionality is improved, but wake formation increases leading to fuel accumulation and flame holding
Solution Approach 1:
The invention extracts the harmful wake formation from the system by introducing a venturi structure that actively removes disturbed airflow. The venturi creates a low-pressure region that draws in ambient air to mix with and dissipate the wake, effectively separating the detection functionality from the harmful flow disturbances it generates
Solution Approach 2:
The venturi structure acts as an intermediary element between the crossfire tube/flame detector and the main airflow. It mediates the interaction by creating a controlled mixing zone where wake-dissipating ambient air is introduced, allowing the detection device to function while its harmful effects are neutralized
2Reliability
If compressed air flows past structures such as crossfire tubes, then these structures perform their detection or control functions, but pressure drop across the liner increases
Solution Approach 1:
The invention changes the pressure parameters within the airflow by introducing a venturi structure. The venturi creates a localized low-pressure region that draws in ambient air, thereby modifying the pressure distribution in the passage and reducing the overall pressure drop across the liner while maintaining control function performance
3Power
If fuel is injected downstream of structures creating wakes, then combustion is achieved, but fuel accumulates in wakes causing flame holding and decreased gas turbine performance
Solution Approach 1:
The invention performs preliminary action by introducing ambient air through the venturi structure before the fuel injection point. This preliminary mixing of ambient air with the wake creates a more uniform flow field that prevents fuel accumulation downstream, thereby eliminating flame holding issues before combustion occurs
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 achieves a wake-free airflow, improving gas turbine flame holding performance by minimizing wake formation and reducing pressure drops, thereby enhancing operational reliability and efficiency.
Implementation Method 1
a venturi (60) disposed downstream from the flow-obstructing element (54) to generally restrict airflow in the air passage (44) and diffuse the airflow
Implementation Method 2
air apertures that introduce higher pressure air to increase velocity and reduce wake recirculation
Data Source
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AI summary
A combustion system is provided having a liner (40), a flow sleeve (42), a flow-obstructing element (54), and a venturi (60). The liner (40) is disposed around a combustion region (38). The flow sleeve (42) is disposed around the liner (40). The liner (40) and the flow sleeve (42) cooperate to create an air passage (44) having an airflow located between the liner (40) and the flow sleeve (42). The flow-obstructing element (54) is disposed within the air passage (44), and generally obstructs the airflow in the air passage (44) to create wakes in the airflow. The venturi (60) is disposed downstream from the flow-obstructing element (54), and generally restricts and diffuses the airflow in the air passage (44) to reduce wakes in the airflow.