Turbine Rotor Blade Tip With Winglet for Cooling and Leakage Control
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Solution Overview
Problem
Conventional blade tip designs, particularly those with a squealer tip, inefficiently use compressor bypass air, reducing plant efficiency and struggling to effectively cool the blade tips due to their proximity to hot combustion gases, leading to excessive cooling air usage and mixing losses.
Innovation Solution
A rotor blade design featuring a winglet at the tip with a truncated suction rail forming a rail gap, combined with a full pressure rail, enhances coolant management and aerodynamic performance by increasing the tip cavity width and optimizing coolant flow within the tip cavity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional squealer tip design is used, then blade tip cooling is provided, but compressor bypass air is used inefficiently reducing plant efficiency
Solution Approach 1:
The patent applies local quality by creating distinct regions within the tip cavity with different functions: the forward portion receives cooling air while the aft portion with the winglet and rail gap optimizes flow attachment and cooling distribution. This localized functional differentiation improves the efficiency of compressor bypass air usage specifically at the blade tip region without compromising overall plant efficiency
Solution Approach 2:
The patent introduces a new dimensional element by adding the winglet that flares radially outward and the rail gap that extends in the chordwise direction. These dimensional additions create a three-dimensional flow management system that improves cooling effectiveness while optimizing the use of compressor bypass air, thereby resolving the efficiency contradiction
2Temperature
If blade tip cooling is enhanced, then cooling effectiveness increases, but mixing losses increase
Solution Approach 1:
The patent converts the potentially harmful mixing of cooling air with mainstream flow into a beneficial effect by using the winglet and rail gap to control and direct this mixing. The controlled mixing pattern enhances cooling effectiveness at the blade tip while minimizing energy losses, effectively turning the harmful mixing phenomenon into a useful cooling mechanism
3Loss of energy
If tip clearance is minimized, then leakage is prevented, but thermal and mechanical expansion causes excessive tip rub
Solution Approach 1:
The patent applies dynamics by creating a tip cavity structure with rails that can accommodate thermal and mechanical expansions. The cavity design allows for dynamic adjustment of the effective clearance as the blade and shroud expand or contract under different operating conditions, preventing both excessive leakage and damaging tip rub while maintaining reliable operation
Data Source
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AI summary
A rotor blade for a turbine of a gas turbine system. The rotor blade includes an airfoil 25 that has a pressure sidewall 26 and a suction sidewall 27 defining an outer periphery, wherein the pressure sidewall and suction sidewall of the airfoil connect along a leading edge 28 and a trailing edge 29; a tip 50 that defines an outer radial end of the airfoil, wherein the tip included a cap 51 on which an outboard projecting rail 53 defines a tip cavity; and a rail gap 90 formed through an aftward section of the rail. The airfoil further includes a winglet 80 positioned near its tip.