Turbine Exhaust Diffuser Flow Redirecting Component
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Solution Overview
Problem
High turn angles in exhaust diffusers of turbine systems lead to flow separation, hindering speed reduction and pressure recovery, and introducing guide vanes does not effectively address these issues due to downstream flow separation.
Innovation Solution
An exhaust diffuser arrangement with a flow redirecting component featuring a concave and convex surface geometry, coupled with a cavity and flow exits, reduces boundary layers and minimizes flow separation by redirecting and energizing the flow, thereby reducing the axial dimension of the diffuser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a high turn angle is used in the exhaust diffuser to reduce axial dimension, then the axial dimension is reduced, but flow separation occurs proximate to the casing wall which hinders speed reduction and pressure recovery
Solution Approach 1:
The flow redirecting component employs a concave surface geometry on its first side to redirect the flow. This curved surface design allows the flow to follow the contour more effectively, reducing flow separation while achieving the necessary flow direction change within a compact axial space.
Solution Approach 2:
The flow redirecting component is divided into distinct surfaces including a concave first side and a convex second side, with flow exits positioned at specific locations. This segmentation allows different portions of the component to perform specialized functions: the concave surface redirects flow while the flow exits energize the boundary layer to prevent separation.
2Speed
If guide vanes are introduced into the duct to rapidly redirect flow, then flow redirection is improved, but flow separation occurs proximate to the downstream surface of the structure
Solution Approach 1:
The flow exits act as intermediaries that introduce a portion of the main flow into the boundary layer region. This injected flow energizes the boundary layer, preventing flow separation on the downstream surface while maintaining rapid flow redirection capability.
Solution Approach 2:
The invention utilizes fluid dynamic principles by extracting and redirecting portions of the main flow through the flow exits to interact with the boundary layer. This pneumatic approach uses the flow itself to control and energize the boundary layer, preventing separation without mechanical moving parts.
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 enables efficient flow redirection and pressure recovery, reducing axial length and minimizing flow separation, thus enhancing the performance of turbine systems by rapidly transitioning the flow from a high-speed inlet to a lower-speed outlet.
Implementation Method 1
a first wall having a first side of a concave surface geometry for redirecting the flow and a second side of a convex surface geometry
Implementation Method 2
only the second wall having at least one flow exit for reducing a boundary layer along the second side of the first wall
Data Source
Figure 1~2
Figure 3~4
AI summary
An exhaust diffuser arrangement (10) for a turbine system includes an inlet (12) for receiving a flow proximate a last stage bucket of the turbine system, the flow flowing in a first flow direction. Also included is a flow redirecting component (30). The flow redirecting component includes a first wall (32) having a first side (34) of a concave surface geometry for redirecting the flow and a second side (36) of a convex surface geometry. The flow redirecting component also includes a second wall (38) spaced downstream of the first wall and having at least one flow exit (50) for reducing a boundary layer along the second side of the first wall.