Flow Mixing Lobes for Exhaust Diffuser Pressure Recovery
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Solution Overview
Problem
Conventional turbomachine exhaust diffusers face challenges in efficiently managing high momentum flows and reducing boundary layer growth, leading to suboptimal pressure recovery and system efficiency.
Innovation Solution
The implementation of flow mixing lobes with specific geometric configurations, including flange members, leg portions, and wing members with non-linear flow conditioning surfaces, which are mechanically linked to the exhaust diffuser's inner surface to guide exhaust gases radially outward and reduce vortex shedding frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional smooth diffuser geometry is used, then manufacturing is simple, but pressure recovery is suboptimal due to boundary layer growth
Solution Approach 1:
The diffuser incorporates localized flow mixing lobes with specific geometric features (leading edges, trailing edges, and curved surfaces) at strategic positions within the diffuser passage. These localized structures create controlled flow separation and reattachment patterns that enhance mixing and reduce boundary layer growth, while the rest of the diffuser maintains a simpler geometry for ease of manufacturing.
Solution Approach 2:
The flow mixing lobes feature curved leading edges and trailing edges with specific radii of curvature. These curved geometries guide the flow smoothly through the diffuser, reducing flow separation and enhancing pressure recovery. The curved surfaces are specifically designed to match the flow patterns and optimize mixing efficiency.
2Productivity
If high momentum flows are not managed, then diffuser structure is simple, but boundary layer growth increases reducing efficiency
Solution Approach 1:
The flow mixing lobes are designed to automatically generate flow separation and reattachment patterns that enhance mixing and reduce boundary layer growth. The geometric features (leading edges, trailing edges, and curved surfaces) self-regulate the flow based on the incoming high momentum conditions, creating vortex structures that enhance mixing without requiring external control systems.
3Manufacturing precision
If flow mixing lobes are added to exhaust diffuser, then pressure recovery improves, but manufacturing complexity increases
Solution Approach 1:
The flow mixing lobes are designed as separate, modular components that can be independently manufactured and then assembled into the diffuser structure. This segmentation allows for specialized manufacturing processes optimized for each component while simplifying the overall fabrication process compared to creating complex integrated geometries.
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 configuration enhances pressure recovery in the exhaust diffuser, reduces boundary layer growth, and improves overall turbomachine efficiency by directing high momentum flows effectively and minimizing flow separation.
Implementation Method 1
The exhaust diffuser is geometrically configured to rapidly decrease the kinetic energy of flow and increase static pressure recovery within the exhaust diffuser
Implementation Method 2
The implementation of flow mixing lobes with specific geometric configurations, including flange members, leg portions, and wing members with non-linear flow conditioning surfaces, which are mechanically linked to the exhaust diffuser's inner surface to guide exhaust gases radially outward and reduce vortex shedding frequencies
Data Source
AI summary
A flow mixing lobe for an exhaust diffuser includes a first flange member having a first leading end, a first trailing end, and an intermediate portion extending therebetween. A second flange member includes a second leading end, a second trailing end, and an intermediate section extending therebetween. A first leg portion includes a first end extending from the first flange member, and a second end. A second leg portion has a first end portion extending from the second flange member, and a second end portion. A wing member is arranged between the first and second leg portions at respective ones of the second end and second end portions. The wing member includes a flow conditioning surface having a non-linear profile extending between the second end and the second end portion.