Turbine Blade Core Removal via Supplementary Passage
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Solution Overview
Problem
The removal of ceramic cores from internal cooling passages in high-pressure turbine blades during the manufacturing process is inefficient, particularly in remote zones with bends, leading to prolonged processing times and potential core remnants due to difficulty in accessing and dissolving core material.
Innovation Solution
A supplementary passage is introduced between the remote zone and the inlet of the cooling passage, defined by a leachable core or machined into the blade, which facilitates quicker core removal by allowing direct access to leaching fluid and later obturated with a plug to prevent cooling air leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the cooling passage is designed with an up-and-down route through the blade to increase cooling duty, then the cooling effectiveness is improved, but the difficulty of removing ceramic cores from remote zones with bends increases
Solution Approach 1:
The cooling passage is segmented into multiple legs (first leg extending from inlet to blade tip, second leg doubling back, third leg doubling back again) to increase cooling surface area and effectiveness while maintaining manageable core removal through strategic segmentation of the leaching process
Solution Approach 2:
A preliminary leaching process is performed to remove ceramic cores from accessible zones before the main leaching process, enabling complete core removal from the complex multi-legged passage structure by preparing the passage in stages
2Temperature
If the cooling passage extends a long distance from the inlet through the blade to maximize cooling coverage, then the cooling duty is increased, but the time required to leach out ceramic cores from remote zones increases
Solution Approach 1:
The leaching process is performed in stages with preliminary action taken to remove cores from accessible zones before proceeding to remote zones, significantly reducing the total leaching time required for long cooling passages
Solution Approach 2:
The leaching process transitions from a single-dimensional approach (inlet to outlet along the passage) to a multi-dimensional approach by introducing leaching fluid through multiple access points and using centrifugal force to enhance penetration into remote zones
3Temperature
If the cooling passage is designed with multiple legs doubling back on itself to increase cooling air utilization, then the cooling efficiency is improved, but the complexity of the internal cooling passage structure increases
Solution Approach 1:
The cooling passage is divided into distinct legs (first leg, second leg, third leg) with clear definitions of their paths and functions, making the complex multi-legged structure easier to manufacture and maintain through systematic segmentation
Solution Approach 2:
The ceramic core acts as an intermediary tool during manufacturing that defines the complex multi-legged passage geometry, allowing the complex structure to be created through a relatively simple casting process using the lost wax method with ceramic molds
4Manufacturing precision
If the leaching process is extended to remove all ceramic cores from remote zones, then the manufacturing quality is improved, but the manufacturing cost increases
Solution Approach 1:
Preliminary leaching actions are taken to remove easily accessible cores before the main leaching process, achieving high core removal completeness more efficiently and reducing overall manufacturing costs by avoiding unnecessary extended processing
Solution Approach 2:
The leaching process is designed to be self-performing through the natural flow of leaching fluid and centrifugal forces, eliminating the need for extended manual intervention or complex additional processing steps to achieve complete core removal
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 solution enables faster and more thorough removal of core material from the cooling passages, reducing manufacturing time and costs while ensuring effective cooling air containment during operation.
Implementation Method 1
a leaching process that dissolves the ceramic cores out of the blade internals using a caustic chemical composition
Implementation Method 2
A supplementary passage is introduced between the remote zone and the inlet of the cooling passage, defined by a leachable core or machined into the blade, which facilitates quicker core removal by allowing direct access to leaching fluid
Implementation Method 3
later obturated with a plug to prevent cooling air leakage
Data Source
AI summary
A cast turbine blade is disclosed and includes an internal cooling passage that passes (e.g., zig-zags or meanders) through the blade from an inlet in the blade root to an outlet in the blade tip. The cooling passage can have a zone at a bend that is at a distance which is remote from the inlet of the cooling passage when the distance from the inlet is measured around the passage, but that is closer to the inlet when the distance from the inlet is measured in a straight line. During casting of the blade, the cooling passage can be defined by a core or cores having a leachable material, the cores being removed after casting by a chemical leaching process. A supplementary passage is also provided for connecting the remote zone to the inlet during the leaching process. The supplementary passage can likewise be defined by a leachable core, or it may be machined into the blade after casting. During the service life of the blade, a plug can be used to obturate the supplementary passage to prevent leakage of cooling air from the cooling passage through the supplementary passage.