Gas Turbine Airfoil Rib Segmentation for Thermal Expansion
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Solution Overview
Problem
Gas turbine engine airfoils face challenges in designing ribs that account for thermal expansion differences between outer walls and internal ribs, affecting the efficiency of cooling systems as they transition from attachment to airfoil sections.
Innovation Solution
The design incorporates a plurality of internal airfoil ribs and cavities that facilitate thermal expansion by creating flexible structures, with specific rib orientations and angles to minimize thermal stresses, and a configuration of cavities that segregate cooling airflow to maintain a uniform temperature distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ribs are designed to be stiff to prevent crushing at the attachment, then structural strength is improved, but thermal expansion accommodation deteriorates
Solution Approach 1:
The rib structure is divided into multiple segments with varying degrees of flexibility. The attachment portion maintains stiffness to prevent crushing, while the airfoil portion incorporates flexible elements that can accommodate thermal expansion. This segmentation allows different parts of the rib to have different mechanical properties optimized for their specific functions.
Solution Approach 2:
Different portions of the rib structure are given different mechanical properties. The attachment end has high stiffness to prevent crushing, while the airfoil section has reduced stiffness to allow thermal expansion. This local differentiation of material or structural properties resolves the contradiction between overall strength and thermal adaptability.
2Adaptability or versatility
If ribs are designed to be flexible to accommodate thermal expansion of outer walls, then thermal expansion accommodation is improved, but structural strength deteriorates
Solution Approach 1:
The rib is segmented into a stiff attachment portion and a flexible airfoil portion. This segmentation allows the structure to be stiff where needed (attachment) and flexible where needed (airfoil), resolving the contradiction between strength and thermal expansion accommodation.
Solution Approach 2:
The rib structure implements local quality by providing different mechanical properties at different locations. The attachment end maintains high strength to prevent crushing, while the airfoil section has reduced stiffness to accommodate thermal expansion, thus satisfying both requirements simultaneously.
3Temperature
If cooling airflow is increased to improve cooling efficiency, then temperature reduction is improved, but thermal stresses worsen
Solution Approach 1:
The patent converts the harmful thermal expansion into a beneficial effect by designing the rib structure to utilize the expansion. The flexible airfoil portion can expand with the outer walls, and the cavity configuration is designed to accommodate this expansion, thereby reducing thermal stresses while maintaining cooling efficiency.
Solution Approach 2:
The cavity configuration is designed to change its geometry in response to thermal expansion. As the outer walls expand, the cavity shape and volume adjust accordingly, maintaining uniform temperature distribution while accommodating thermal stresses. This dynamic adaptation of cavity parameters resolves the contradiction between cooling efficiency and thermal stress.
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 configuration reduces thermal stresses and maintains efficient cooling airflow, extending the operational life of gas turbine components by accommodating thermal expansion while minimizing structural stress.
Implementation Method 1
Because the outer walls are exposed to relatively hot air, they may experience greater thermal expansion than the internal ribs or walls
Implementation Method 2
The airfoils may include outer walls along with internal ribs or walls that form internal cavities through which a cooling airflow may flow from attachments coupled to the airfoils
Data Source
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AI summary
An airfoil (120) for use with a gas turbine engine (20) includes a pressure side wall (402) and a suction side wall (404). The suction side wall (404) is configured to be exposed to less pressure than the pressure side wall (402) during operation of the gas turbine engine (20). The blade (120) also includes a plurality of ribs (425) forming a plurality of trapezoidal shaped cavities to receive a cooling airflow. The plurality of ribs (425) being shaped in a way to allow for thermal growth of the airfoil, while minimizing stress in the airfoil (120).