Tapered Tip Treatment Bars for Gas Turbine Fatigue Reduction
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Solution Overview
Problem
Existing tip treatment bar arrangements in gas turbine engines are complex and expensive due to the need for precise axial location and damping to prevent high cycle fatigue failure caused by vibration resonance, which complicates the support structure.
Innovation Solution
The use of tapered tip treatment bars with complementary tapered openings in annular supports, along with damping elements and integral ribs for axial alignment and stiffness, simplifies the design and reduces production costs by allowing for uniform cross-sections and easier manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tip treatment bars are supported in apertures with damping elements and shoulders for axial location, then vibration-induced fatigue is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent removes the shoulders from the tip treatment bars, extracting the axial location function to the tapered aperture walls instead. This simplifies the bar design while maintaining proper positioning through the tapered geometry of the aperture that retains the tapered bar end.
Solution Approach 2:
The patent changes the geometric parameters of both the bar ends and aperture openings to tapered shapes. This parameter change enables the bar ends to be retained in the apertures without requiring additional shoulders, while still providing proper axial location and facilitating damping element installation.
2Manufacturing precision
If tip treatment bars incorporate shoulders for axial location, then proper positioning is ensured, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts the axial location function from the bar shoulders and transfers it to the tapered aperture geometry. The tapered walls of the aperture provide the locating surface, eliminating the need for complex shoulder features on the bars themselves.
Solution Approach 2:
Instead of providing axial location features on the bar (shoulders), the patent inverts the approach by providing the locating features on the aperture (tapered walls). This reversal simplifies bar manufacturing while achieving the same positioning function.
3Reliability
If damping elements are installed between bar ends and support surfaces, then vibration resonance is reduced, but device complexity increases
Solution Approach 1:
The patent introduces damping elements as intermediary components between the tapered bar ends and the tapered aperture walls. These damping elements mediate the interaction between the bar and support structure, reducing vibration transmission while the tapered geometry ensures proper installation and retention.
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 effectively reduces vibration-induced fatigue by damping the tip treatment bars, delaying stall onset and reducing the complexity and cost of the engine casing arrangement while maintaining structural integrity.
Implementation Method 1
damping elements being provided between the surfaces of the bar ends and the internal walls of the support apertures
Data Source
AI summary
There is presented a casing arrangement for a gas turbine engine. The casing arrangement includes a plurality of tip treatment bars extending between a pair of spaced-apart annular supports, with each tip treatment bar being elongate and supported at each end by a respective support such that each end of the bar is received within an opening formed in the respective support. At least the ends of each tip treatment bar are tapered in transverse cross-section so as to have a wedge-shaped profile, and the openings in the supports have a complementary tapered shape for receipt and retention of the bar ends therein.