Gas Turbine Diffuser Flapped Struts Flow Separation
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Solution Overview
Problem
Existing gas turbine diffusers experience flow separation and reduced static pressure recovery due to support struts when operating in partial load conditions, leading to decreased efficiency.
Innovation Solution
The diffuser design includes circumferentially-spaced struts with flaps that extend between an annular inner and outer wall, where the flaps help control the swirl and circulation of combustion gases, reducing flow separation and enhancing static pressure recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If support struts are added to the diffuser to provide structural support, then the mechanical strength and stability are improved, but the gas flow is obstructed and flow separation occurs leading to reduced static pressure recovery
Solution Approach 1:
The strut is segmented into multiple parts: a main body portion and a movable flap portion. This segmentation allows the strut to provide structural support while the flap can move independently to accommodate varying flow conditions, reducing flow separation and maintaining static pressure recovery capability across different operating loads.
Solution Approach 2:
The flap portion of the strut is designed to be movable rather than fixed. It can rotate or pivot about a hinge point to adjust its angle relative to the main body. This dynamic adjustment allows the flap to align with the gas flow direction under different operating conditions, minimizing flow separation and turbulence while maintaining structural integrity.
2Adaptability or versatility
If the gas turbine operates in partial load conditions with higher swirl, then the adaptability to varying load conditions is improved, but flow separation over the struts increases reducing efficiency
Solution Approach 1:
The movable flap is driven by a mechanism (such as a bellows or spring system) that responds to changes in gas flow conditions. Under partial load conditions with higher swirl, the flap rotates to a different angle to accommodate the increased swirl, reducing flow separation and energy loss. Under base load conditions, the flap returns to its original position, maintaining optimal performance across the full operating range.
Solution Approach 2:
The flap angle parameter is changed dynamically in response to operating conditions. By adjusting this geometric parameter, the strut can adapt to different flow patterns and swirl intensities, minimizing flow separation and energy loss across varying load conditions while maintaining structural support.
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 use of flaps on the struts minimizes flow separation and increases the static pressure recovery capability, thereby improving the operating efficiency of the gas turbine, especially during partial load conditions.
Implementation Method 1
The increased swirling may cause the flow of combustion gases over the struts to separate, thus reducing the static pressure recovery capability of the diffuser
Data Source
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AI summary
A gas turbine diffuser (108) for use with a gas turbine power system is provided. The diffuser includes an annular inner wall (202), an annular outer wall (204) circumscribing the inner wall such that a gas path (206) is defined between the inner and outer walls, and a plurality of circumferentially-spaced struts (208) extending from the inner wall to the outer wall across the gas path, wherein at least one of the struts includes a flap (320, 420, 520, 620).