Axially Offset Tip Shroud Cutter Teeth for Lower Aerodynamic Loss
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Solution Overview
Problem
Turbine blade tip shrouds experience aerodynamic inefficiencies and reduced creep life due to interactions with stationary components, leading to performance losses and imbalance.
Innovation Solution
A turbine blade tip shroud design featuring axially offset cutter teeth and specific surface profiles, including a first cutter tooth adjacent the leading edge and a second tooth axially spaced from the first, with defined Cartesian coordinate values for the tip rail and edge surfaces, to enhance balance and extend creep life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tip shroud interacts with stationary components to direct hot gases, then the aerodynamic function is achieved, but aerodynamic losses and performance efficiency deteriorate
Solution Approach 1:
The patent applies local quality by modifying specific regions of the tip shroud through selective material removal. The cutter teeth are positioned at specific locations (e.g., 12 o'clock and 6 o'clock positions) to locally alter the interaction characteristics with stationary components, thereby reducing aerodynamic losses in critical areas while maintaining overall aerodynamic function.
Solution Approach 2:
The patent introduces asymmetry by removing material preferentially from certain sides of the tip shroud (e.g., removing material from the pressure side more than the suction side). This asymmetric modification creates an imbalance that reduces the harmful interaction with stationary components and minimizes aerodynamic losses.
2Reliability
If the tip shroud interacts with stationary components, then gas direction function is achieved, but creep life is reduced
Solution Approach 1:
The patent applies the extraction principle by removing material from the tip shroud using cutter teeth. This extraction of material reduces the contact area and interaction forces between the rotating tip shroud and stationary components, thereby reducing wear and extending creep life while maintaining the gas direction function.
Solution Approach 2:
The patent discards material from high-wear regions of the tip shroud through the cutter tooth process. By removing material from areas that experience the most harmful interaction with stationary components, the patent extends the service life of the tip shroud by reducing cumulative wear damage.
3Ease of manufacture
If the tip shroud maintains conventional symmetric design, then manufacturing simplicity is preserved, but aerodynamic performance and balance deteriorate
Solution Approach 1:
The patent transitions from symmetric to asymmetric design by positioning cutter teeth to remove material preferentially from specific sides of the tip shroud. This asymmetric modification improves aerodynamic performance and balance by reducing harmful interactions, while the cutter tooth process itself remains relatively simple to implement.
Solution Approach 2:
The patent applies local quality modifications through the cutter teeth, which selectively remove material from specific regions of the tip shroud. This localized approach allows for improved aerodynamic performance without requiring complete redesign of the entire component, thus maintaining reasonable manufacturing simplicity.
4Device complexity
If the tip shroud uses conventional cutter tooth configuration, then structural simplicity is maintained, but balance and creep life deteriorate
Solution Approach 1:
The patent modifies the conventional symmetric cutter tooth configuration by positioning cutters at specific asymmetric locations (e.g., 12 o'clock and 6 o'clock positions) and removing material preferentially from certain sides. This asymmetric configuration improves balance and reduces wear, extending creep life while maintaining relatively simple tooling and process requirements.
Data Source
AI summary
A turbine blade tip shroud has a first cutter tooth extending from a tip rail from one of the upstream side and the downstream side of the tip rail and adjacent the leading edge of the body. The tip shroud also includes a second cutter tooth extending from the tip rail from the other side of the tip rail at a position axially distant from the first cutter tooth. The cutter teeth are thus axially offset. The tip shroud can be initially manufactured with this shape or may be modified from a used tip shroud having, for example, opposing cutter teeth near a leading edge of a body of the tip shroud. Various tip shroud surface profiles, which are expressed in terms of Cartesian coordinates, are also provided.