Exhaust Diffuser Strut Airfoil Design for Pressure Recovery
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Solution Overview
Problem
Conventional exhaust diffusers in torque-generating turbines face inefficiencies due to flow separation and high drag coefficients at varying angle of attack, leading to reduced pressure recovery and potential blockages.
Innovation Solution
The design incorporates airfoils with a higher range of angle of attack capability, featuring differences in thickness, leading edge radius, and camber, along with a twin-strut configuration and varying angle of incidence to minimize drag and enhance pressure recovery, while maintaining structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional prismatic struts with uniform cross-section are used, then structural stability is maintained, but drag coefficient increases and pressure recovery decreases
Solution Approach 1:
The strut cross-section is made variable along its span rather than uniform. The airfoil cross-section changes from root to tip, with different thickness, camber, and leading edge radius at different positions, allowing the strut to adapt to varying flow conditions and reduce drag while maintaining structural integrity
Solution Approach 2:
Different sections of the strut are given different aerodynamic properties. The root section has one airfoil configuration while the tip section has another, optimized for local flow conditions. This local optimization reduces overall drag and improves pressure recovery without compromising structural stability
2Reliability
If single airfoil design is used for struts, then manufacturing is simplified, but flow separation occurs at varying angles of attack
Solution Approach 1:
Different airfoil sections along the strut span have different geometric parameters (thickness, camber, leading edge radius) optimized for local flow conditions. This prevents flow separation at varying angles of attack by adapting the airfoil shape to match the local flow angle, improving reliability while the gradual variation keeps manufacturing feasible
3Strength
If struts with large cross-section are used, then structural strength is improved, but drag increases and pressure recovery is reduced
Solution Approach 1:
The strut cross-sectional area varies along its span rather than being constant. The airfoil dimensions change from root to tip, allowing the strut to maintain sufficient strength at the root while minimizing drag at the tip where the flow is more favorable, achieving an optimal balance between strength and drag reduction
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 low momentum fluid generation, minimizes blockages, and improves pressure recovery by adapting to changing flow angles, resulting in a more efficient and stable exhaust diffuser.
Implementation Method 1
Conventional exhaust diffusers in torque-generating turbines face inefficiencies due to flow separation and high drag coefficients at varying angle of attack
Implementation Method 2
high drag coefficients at varying angle of attack, leading to reduced pressure recovery
Implementation Method 3
an exhaust diffuser to slow down the fluid flow and thereby enhance pressure recovery
Data Source
Figure 1
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AI summary
Exhaust diffuser and method for manufacturing an exhaust diffuser It is described an exhaust diffuser for a torque-generating turbine, in particular a torque-generating gas turbine, the exhaust diffuser comprising an inner member having an outer surface and an outer member having an inner surface, the inner member and the outer member forming an annular channel, at least a first supporting strut (5) connecting the inner member and the outer member, the first supporting strut (5) extending essentially radially from the inner surface to the outer surface, the first supporting strut comprising a middle section (7) having a first airfoil and an outer section (6) having a second airfoil, and the second airfoil differing from the first airfoil in shape to be able to handle a higher range of angle of attack. Furthermore, it is described a method for manufacturing an exhaust diffuser.