Turbine Diffuser Boundary Layer Energization
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Solution Overview
Problem
Traditional gas turbine systems lose efficiency due to energy utilized in compressing bleed air for clearance control, leading to reduced exhaust energy recovery.
Innovation Solution
A system and method that utilize a cooling manifold to direct a cooling fluid, such as pressurized bleed air or steam, to energize the boundary layer in the diffuser section, reducing pressure losses and enhancing exhaust energy recovery by injecting the fluid downstream of the turbine blades with higher pressure than the exhaust flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressurized bleed air is used for clearance control of turbine blades, then clearance control is achieved, but energy efficiency deteriorates due to loss of compression energy
Solution Approach 1:
The patent recovers the spent cooling air from the turbine casing after it has performed its clearance control function, and reuses it to energize the boundary layer in the diffuser section. This prevents the energy contained in the cooled air from being wasted and improves overall system efficiency while maintaining clearance control functionality.
Solution Approach 2:
The system uses the cooling air that has already served its purpose in maintaining blade clearance to provide a secondary function of energizing the boundary layer. The same fluid resource performs multiple useful functions within the system, reducing the need for additional energy inputs.
2Reliability
If traditional clearance control is implemented, then blade clearance is maintained, but exhaust energy recovery deteriorates
Solution Approach 1:
The cooling air system serves multiple functions: first for clearance control of turbine blades, then for energizing the boundary layer in the diffuser. This multi-functionality allows the system to maintain blade clearance while simultaneously improving exhaust energy recovery, eliminating the trade-off between these two objectives.
3Reliability
If cooling air is vented to enclosure atmosphere, then clearance control is maintained, but system efficiency deteriorates
Solution Approach 1:
Instead of venting the spent cooling air to the enclosure atmosphere where its energy would be lost, the system captures and redirects this air to the diffuser section. The cooling air continues to provide useful work by energizing the boundary layer, preventing energy loss and improving overall system efficiency.
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 reduces pressure losses and increases energy recovery by strengthening the boundary layer, allowing more energy to be utilized in the gas turbine system and downstream processes, thereby improving overall thermodynamic cycle efficiency.
Implementation Method 1
the energizing ports direct the energizing flow along the inner surface of the wall to energize a boundary layer along the wall
Implementation Method 2
a first pressure of the energizing flow is greater than a second pressure of the exhaust flow at the energizing port
Data Source
AI summary
A system includes a turbine with an expansion section configured to expand an exhaust flow in a downstream direction, such that the expansion section includes a plurality of stages and a diffuser section coupled downstream of the expansion section. The diffuser section receives the exhaust flow along an exhaust path and an energizing flow along a wall, and the diffuser section includes the wall comprising an inner surface, so the wall is disposed about the exhaust path, and an energizing port disposed in the wall at or downstream of a last stage of the plurality of stages of the expansion section. The energizing port is configured to direct the energizing flow along the inner surface of the wall to energize a boundary layer along the wall, and a first pressure of the energizing flow is greater than a second pressure of the exhaust flow at the energizing port.