Double Tip Flag Channels for Turbine Blade Tip Cooling
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Solution Overview
Problem
Existing cooling systems for turbine blades, particularly at the tip region, are inadequate in managing thermal stress and heat loading, leading to potential deterioration and reduced blade life due to insufficient cooling, which can be exacerbated by high temperatures and tip leakage flow.
Innovation Solution
A double tip flag cooling system for turbine blades, featuring multiple independent cooling channels, including a leading channel, primary and secondary tip flag channels, and a trailing channel, with dedicated film cooling holes and pin bank cavities, to enhance cooling efficiency and control thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single cooling channel is used in the blade, then the device complexity is low, but the cooling effectiveness at the tip region is insufficient
Solution Approach 1:
The cooling system is divided into multiple independent channels: a leading channel for the leading edge region, and tip flag channels (primary and secondary) for the tip region. Each channel independently delivers cooling air to its designated zone, allowing optimized cooling effectiveness for each region without requiring a single complex channel design.
Solution Approach 2:
Different cooling strategies are applied to different regions of the blade. The leading channel provides cooling to the leading edge, while the tip flag channels specifically target the tip region. This localized approach allows each channel to be optimized for its specific region's thermal requirements, improving overall cooling effectiveness.
2Reliability
If cooling air is delivered through a single channel, then the manufacturing is simple, but the thermal stress control is inadequate
Solution Approach 1:
The thermal stress management system is segmented into multiple cooling channels that can be independently designed and manufactured. The leading channel and tip flag channels are separate, allowing each to be optimized for its specific thermal management function while maintaining manufacturing feasibility through modular design.
Solution Approach 2:
Different cooling airflows are directed to different regions experiencing different thermal loads. The tip flag channels specifically address the high thermal stress region at the blade tip, while the leading channel addresses the leading edge region, providing localized thermal stress control.
3Reliability
If cooling passages are extended to the blade tip, then the tip cooling is improved, but the pressure drop increases
Solution Approach 1:
The cooling system segments the tip region cooling into primary and secondary tip flag channels. This segmentation allows the cooling air to be delivered more efficiently to the tip region without requiring excessively long single passages, thereby reducing the overall pressure drop while maintaining effective tip cooling.
Solution Approach 2:
The tip flag channels are specifically designed to deliver cooling air directly to the tip region where it is most needed, rather than extending cooling passages throughout the entire blade length. This localized approach improves tip cooling effectiveness while minimizing unnecessary pressure drop in other regions.
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
The system provides enhanced cooling of turbine blade tips by delivering high-pressure cooling air through separate channels, minimizing pressure drop and thermal stress, thereby improving blade life and reducing inefficiencies.
Implementation Method 1
The conduits channel cooling air and include at least three conduits. One conduit defines a leading channel that is substantially straight and that extends in a radial direction from the base to an end at the tip, where the leading channel is configured to eject a first part of the cooling air from the blade through the leading edge.
Implementation Method 2
Compressor bleed air may be used for cooling and may be delivered through cooling passages in blade roots and into the blades to remove heat transferred to the blade from the hot gas stream.
Data Source
AI summary
Systems provide enhanced cooling of tip regions of turbine blades. A cooling system includes a turbine blade with a root, a base, a tip, a leading edge, a trailing edge, an outer structure that includes a pressure side wall, a suction side wall and a tip cap at its tip. A core in the blade defines a leading channel that ejects cooling air through the leading edge. A primary tip flag channel ejects cooling air through the tip and the trailing edge. A secondary tip flag channel ejects cooling air through the trailing edge. The primary tip flag channel and the secondary tip flag channel promote cooling of the tip due to the locations in the tip area and their delivery of low temperature and high pressure cooling air thereto.