Turbomachine Blade Cooling Circuit Design
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Solution Overview
Problem
High pressure turbine blades in turbojet engines require continuous improvement in cooling efficiency due to evolving operating conditions and manufacturing methods, necessitating a more effective cooling circuit design to reduce fuel consumption and extend blade service life.
Innovation Solution
The design incorporates a turbine blade with a unique cooling circuit featuring a central duct that supplies air to a cavity under the squealer, reducing air flow rates and effectively cooling critical areas like the lower surface wall near the tip and trailing edge, while maintaining high flow rates in other ducts to optimize heat exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a traditional cooling circuit is used in turbine blades, then the blade structure is simpler, but the cooling efficiency is insufficient and fuel consumption increases
Solution Approach 1:
The cooling circuit is divided into multiple independent ducts (first duct, second duct, third duct, fourth duct) with distinct functions. Each duct serves specific cooling zones, allowing optimized airflow distribution and improved overall cooling efficiency while maintaining manageable complexity through modular design
Solution Approach 2:
Different regions of the blade receive cooling air with different characteristics. The first duct provides cooling air to the leading edge, the second duct to the middle portion, the third duct to the lower surface wall near the tip, and the fourth duct to the trailing edge. This localized cooling approach optimizes heat exchange in each critical area
2Reliability
If high air flow rate is used for cooling, then cooling effectiveness improves, but fuel consumption increases
Solution Approach 1:
The invention changes the parameters of cooling air by creating separate ducts that deliver air at different flow rates and temperatures to different blade regions. The second duct specifically delivers high flow rate air to the middle portion, while other ducts optimize for their respective zones, improving overall cooling efficiency and extending blade service life without proportionally increasing total air consumption
3Ease of manufacture
If cooling air is supplied to all blade regions through a single circuit, then the circuit structure is simpler, but heat exchange efficiency in critical areas is reduced
Solution Approach 1:
The cooling circuit is segmented into four separate ducts, each optimized for specific heat exchange requirements. The second duct is specifically designed with high flow rate capability for the middle portion, while the third duct is positioned to effectively cool the lower surface wall near the tip. This segmentation ensures optimal heat exchange efficiency in each critical area
Solution Approach 2:
Each duct is tailored to provide appropriate cooling characteristics to its target region. The local quality of cooling (flow rate, temperature, distribution) is optimized for each blade section, maximizing heat exchange efficiency where it is most needed
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 reduces the air flow necessary for cooling the blade's middle portion, preserving cold air to effectively cool critical regions and extending blade service life by enhancing heat exchange and reducing fuel consumption.
Implementation Method 1
the air conveyed to the cavity under the squealer is not heated, which allows to effectively cool the lower surface wall close to the tip and to the trailing edge
Data Source
AI summary
A turbine vane includes a root carrying a blade terminated by a squealer tip, the blade having intrados and extrados walls, a leading edge, a trailing edge, and a tip wall delimiting a bottom of the squealer tip, by which the intrados wall is connected to the extrados wall. The blade also includes: a serpentine median circuit, including a first radial pipe that collects air at the root and is connected by a first bend to a second radial pipe that is connected by a second bend to a third radial pipe; a cavity under the squealer tip running along the extrados wall and extending from a central region of the squealer tip to the trailing edge; and a central radial pipe collecting air at the root and extending between at least two of the three pipes of the median circuit and directly supplying the cavity under the squealer tip.