Turbine Rotor Blade Tip Cooling via Segmented Channel Design
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Solution Overview
Problem
Conventional turbine rotor blades face challenges in effectively cooling the blade tip portion due to high operating temperatures, leading to potential mechanical issues and reduced engine efficiency, especially in areas where tip leakage flow causes efficiency loss and increased Specific Fuel Consumption (SFC).
Innovation Solution
The design incorporates a step between the tip edge and the tip cap, with a cooling hole having an open channel section and a closed channel section, which extends from the parapet wall through the tip cap, preventing blockages and maintaining cooling efficiency even when the blade rubs against the shroud, and is manufactured using electro-discharge machining or additive techniques to ensure unobstructed airflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling holes are used in turbine rotor blades, then cooling air can be delivered to the blade interior, but the cooling holes become blocked when the blade rubs against the shroud, reducing cooling effectiveness
Solution Approach 1:
The cooling hole is divided into two distinct sections: a closed channel section extending through the tip cap and an open channel section in the parapet wall. This segmentation allows the cooling functions to be separated - the closed section delivers cooling air to the tip cap while the open section provides cooling to the parapet wall, preventing blockage-related failures
Solution Approach 2:
Different sections of the cooling hole structure are given different geometric qualities - the closed channel section has enclosed walls for directed airflow to the tip cap, while the open channel section has an exposed geometry in the parapet wall that prevents complete blockage. This local differentiation optimizes cooling effectiveness for each specific location
2Strength
If cooling air is delivered through internal passages to maintain blade temperatures, then material and stress levels are maintained, but cooling effectiveness is reduced in high-temperature areas such as blade tips
Solution Approach 1:
The cooling approach transitions from a single-dimension internal passage system to a multi-dimensional configuration by extending cooling holes through the tip cap and into the parapet wall structure. This three-dimensional cooling network delivers cooling air to previously hard-to-reach areas, significantly improving tip temperature control
3Loss of energy
If the blade tip is cooled effectively, then tip leakage flow is reduced and engine efficiency is improved, but the device complexity increases due to additional cooling hole sections
Solution Approach 1:
The cooling hole structure merges the tip cap cooling function and the parapet wall cooling function into a single integrated feature. By forming one continuous cooling hole that passes through the tip cap and opens in the parapet wall, the design achieves dual cooling functionality without requiring separate cooling systems, thus reducing overall device complexity
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 enhances tip portion cooling, reduces tip leakage flow, and improves engine efficiency by maintaining acceptable blade temperatures, allowing for increased operating temperatures and reduced cooling air usage, thereby optimizing fuel consumption and extending the service life of the turbine blades.
Implementation Method 1
ducting cooling air through internal passages and then venting the cooling air through holes formed in the airfoil
Implementation Method 2
manufactured using electro-discharge machining or additive techniques
Data Source
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AI summary
A turbine rotor blade is provided for a turbine section of an engine. The turbine rotor blade includes a platform and an airfoil extending from the platform into a mainstream gas path of the turbine section. The airfoil includes a first side wall; a second side wall joined to the first side wall at a leading edge and a trailing edge; a tip cap extending between the first side wall and the second side wall; a first parapet wall extending from the first side wall; and a first cooling hole through the tip cap and the first parapet wall configured to deliver cooling air. The first cooling hole has a closed channel section and an open channel section. The open channel section forms a slot.