Gas Turbine Rotor Blade Flared Tip Cooling
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Solution Overview
Problem
The trailing edge region of turbine rotor blades is challenging to cool effectively due to its proximity to the turbine shroud, which limits the leakage of hot operating fluid and hampers cooling efficiency.
Innovation Solution
A rotor blade design featuring a flared tip configuration with obliquely extending suction and pressure side walls, forming a tip cavity with slots and apertures that enhance cooling medium flow and distribution, particularly around the trailing edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the blade tip is positioned close to the turbine shroud to minimize tip clearance, then turbine efficiency is improved, but cooling effectiveness of the trailing edge region deteriorates
Solution Approach 1:
The blade tip is segmented into distinct functional zones: a tip cap forming a sealed cavity, flared pressure and suction side walls creating cooling channels, and a trailing edge portion with integrated cooling apertures. This segmentation allows independent optimization of sealing and cooling functions in different regions.
Solution Approach 2:
A tip cavity acts as an intermediary chamber between the internal cooling passages and the external environment. Cooling medium flows through this intermediary space, allowing effective cooling of the trailing edge region while maintaining minimal tip clearance to the shroud.
2Temperature
If internal cooling passages are used to cool the blade, then blade temperature is reduced, but the trailing edge region remains difficult to cool effectively
Solution Approach 1:
The cooling approach transitions from purely internal 3D passages to a 2D planar cooling surface created by the flared tip geometry. The pressure and suction side walls extend radially outward to form a cooling surface that directly contacts the trailing edge region, enabling effective heat removal from previously inaccessible areas.
Solution Approach 2:
Cooling medium is routed through the tip cavity formed by the flared tip structure, utilizing fluid flow dynamics to distribute coolant effectively across the trailing edge region. The hydraulic design of the cooling channels ensures adequate coolant distribution and heat transfer in the critical trailing edge area.
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 design improves cooling efficiency of the trailing edge by increasing the volume of the tip cavity and directing the cooling medium effectively, thereby reducing surface temperatures and extending the blade's service life.
Implementation Method 1
a cooling medium is routed through the internal cooling passages. A portion of the cooling medium may be routed out of the internal cooling passages through various cooling holes defined along the blade surface, thereby reducing high surface temperatures
Implementation Method 2
This configuration is generally due to the lack of an appropriate wall thickness of the blade along the trailing edge
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A rotor blade includes an airfoil 106 having a blade tip 120 and a tip cavity 134 formed at the blade tip. The blade tip defines a radially outer surface of the airfoil. The tip cavity includes a tip cap 136 that is recessed radially inwardly from the tip and surrounded by pressure 114 and suction 116 side walls of the airfoil. The tip cap is in fluid communication with an internal cavity defined within the airfoil. A portion of the suction and/or the pressure side wall that define the tip cavity extends obliquely outwardly from the tip cavity. A plurality of slots 148 is defined in the suction and/or the pressure side wall along the radially outer surface proximate to the trailing edge of the airfoil.