Subsonic Shock Strut Inflection Point Design
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Solution Overview
Problem
Existing gas turbine engine struts face challenges in increasing thickness without compromising performance, particularly in applications where thick struts lead to significant loss and blockage penalties.
Innovation Solution
The design incorporates a subsonic strut with an airfoil shape featuring a forebody and an aft body with an inflection point, which produces subsonic shock pressure recovery, and includes active boundary layer suction to enhance flow stability and pressure recovery, allowing for increased thickness-to-chord ratios with reduced trailing edge thickness and blockage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the strut thickness is increased to improve structural strength, then the strength increases, but the blockage penalty and performance loss increase
Solution Approach 1:
The patent changes the geometric parameters of the strut by introducing an inflection point in the aft body and using constant radius curves with different radii. This allows the strut to maintain increased thickness for strength while optimizing the thickness-to-chord ratio to reduce blockage penalties and performance losses in subsonic flow
Solution Approach 2:
The patent employs constant radius curves in both the forebody and aft body of the strut. The aft body specifically uses a transition from one constant radius curve to another, creating smooth curvature variations that reduce flow separation and pressure losses, thereby maintaining performance despite increased thickness
2Strength
If the strut thickness is increased to improve structural integrity, then the structural integrity improves, but the flow blockage increases
Solution Approach 1:
The patent optimizes the thickness-to-chord ratio parameter by introducing an inflection point in the aft body. This allows the strut to achieve the necessary structural integrity through increased thickness while carefully controlling the overall chord length and thickness distribution to minimize flow blockage in the subsonic passage
3Stress or pressure
If the aft body length is increased to improve pressure recovery, then the pressure recovery improves, but the device complexity increases
Solution Approach 1:
The patent uses constant radius curves to define the forebody and aft body shapes. This geometric approach provides smooth curvature transitions that promote favorable pressure gradients and flow reattachment, achieving pressure recovery through elegant geometric forms rather than complex internal structures or additional components
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 enables struts with enhanced thickness while minimizing performance losses, achieving improved pressure recovery and flow stability, thereby addressing the limitations of existing systems.
Implementation Method 1
The aft body of the gas turbine engine subsonic strut has an inflection point that produces a subsonic shock pressure recovery when disposed in a flow path having subsonic flow
Implementation Method 2
the inflection point may be structured to initially encourage flow separation while the aft body may be structured to provide an adequate length to reattach the flow
Implementation Method 3
The apparatus may further include an active boundary layer suction port located downstream of the inflection point. The active boundary layer suction point may be used in concert with the inflection point to achieve a more aggressive pressure recovery and an increased flow stability
Data Source
Figure 1~2
Figure 3~4B
AI summary
A gas turbine engine strut is disclosed as having a will forebody positioned upstream of a point of maximum thickness and an aft body positioned downstream of the point of maximum thickness. The aft body includes a discontinuity in a curvature distribution which provides for a "subsonic shock." The discontinuity in curvature distribution can include in inflection point that marks a transition from a curvature associated with an upstream portion of the aft body to a second curvature associated with a downstream portion of the aft body. In some forms, the aft body can additionally include boundary layer aspiration. The gas turbine engine strut can be symmetrical about a centerline.