Gas Turbine Diffuser Strut with Inclined Leading Edge
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Solution Overview
Problem
Gas turbine diffusers face structural support challenges while also experiencing aerodynamic inefficiencies due to struts, which create blockage and lead to local pressure loss and reduced thermal efficiency, especially under off-design conditions with excessive swirling flow.
Innovation Solution
The introduction of a compound sweep design for the strut's leading and trailing edges, where the leading edge is inclined towards the exhaust stream's direction and the trailing edge is inclined opposite to it, reducing Mach number and minimizing shock losses, and controlling blade surface pressure distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If struts are added to provide structural support, then structural rigidity is improved, but pressure recovery deteriorates due to blockage and local loss
Solution Approach 1:
The strut leading edge is designed with a curved surface that is inclined towards the section outlet, rather than being straight or perpendicular to the wall. This curvature allows the exhaust stream to flow smoothly over the strut surface, reducing flow separation and minimizing the blockage effect, thereby reducing local pressure loss while maintaining structural support functionality
Solution Approach 2:
Only the leading edge portion of the strut is inclined towards the section outlet, while other portions may have different orientations. This localized inclination optimizes the aerodynamic flow over the critical leading edge region where flow separation most commonly occurs, improving pressure recovery without compromising overall structural support
2Strength
If struts are added to provide structural support, then structural rigidity is improved, but thermal efficiency deteriorates
Solution Approach 1:
The curved and inclined leading edge design reduces flow separation and minimizes turbulence behind the strut, decreasing energy losses in the exhaust stream. This improves thermal efficiency by maintaining more useful kinetic energy in the exhaust flow while the strut continues to provide necessary structural support
3Strength
If struts are added to provide structural support, then structural rigidity is improved, but flow separation increases under off-design conditions
Solution Approach 1:
The curved leading edge surface guides the exhaust stream smoothly over the strut, preventing flow separation even under off-design conditions with excessive swirling flow. The inclination towards the section outlet aligns the surface more favorably with the flow direction, reducing adverse pressure gradients that cause separation
Solution Approach 2:
The leading edge is inclined at a specific angle towards the section outlet, changing the geometric parameters of the strut to optimize flow attachment. This angular parameter adjustment ensures that the flow remains attached to the strut surface under a wider range of operating conditions, reducing flow separation
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 design enhances pressure recovery and thermal efficiency by reducing flow separation and maintaining performance even at off-design conditions, improving the overall efficiency of the gas turbine diffuser.
Implementation Method 1
The leading edge has a first edge portion and a second edge portion, wherein the second edge portion of the leading edge is located between the first edge portion of the leading edge and the second wall portion. The first edge portion of the leading edge is inclined towards the section outlet with regard to a normal direction perpendicular to the first wall portion at a first leading end point at which the leading edge meets the first wall portion.
Data Source
AI summary
Described is a gas turbine diffuser (300) comprising a strut (302) with a leading edge (304) extending between a first wall portion (308a) and a second wall portion (308b), wherein a first edge portion (304a) of the leading edge (304) is inclined towards a diffuser section outlet (326), i.e. in flow direction (328) of an exhaust stream, with regard to a normal direction (319a) perpendicular to the first wall portion (308a) at a first leading end point (320a) at which the leading edge (304) meets the first wall portion (308). Hence the leading edge (304) is partially inclined towards a diffuser section outlet (326).