Turbomachine Blade Shank Reuse with Ceramic Airfoil Insert
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Solution Overview
Problem
The high cost and inefficiency of replacing turbomachine blades with ceramic matrix composite (CMC) blades, especially for complex shapes, and the mismatch in useful life between the shank and airfoil, lead to increased expenses and unnecessary replacements.
Innovation Solution
A method involving the removal of the metal airfoil from a used turbomachine blade, forming a radially extending opening in the shank, and inserting a ceramic airfoil with a nub to attach it to the remaining base, allowing the reuse of the metal shank while providing the benefits of a ceramic airfoil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the entire blade is replaced with a ceramic matrix composite (CMC) blade, then the blade weight is reduced and performance is improved, but the manufacturing cost increases significantly
Solution Approach 1:
The blade is divided into two distinct parts: a metal shank (root portion) and a ceramic airfoil (blade portion). This segmentation allows each part to be manufactured using optimal materials and processes for its specific requirements, with the ceramic airfoil being the only portion requiring expensive CMC manufacturing.
Solution Approach 2:
The expensive ceramic airfoil portion is extracted as a separate replaceable component from the metal shank. This extraction allows the ceramic airfoil to be manufactured independently and attached to the reusable metal shank, avoiding the need to manufacture the entire blade as expensive CMC.
2Reliability
If the entire blade is replaced with a ceramic matrix composite (CMC) blade, then the blade performance is improved, but the device complexity increases
Solution Approach 1:
The blade structure is segmented into a metal shank with standardized geometry and a separate ceramic airfoil. This segmentation simplifies the overall system by allowing the metal shank to serve as a reusable platform that can accommodate different airfoil configurations.
3Temperature
If the shank is made relatively long to distance the hot gas path from the rotor wheel, then the blade can operate at higher temperatures, but the manufacturing cost increases
Solution Approach 1:
The hot gas path exposure is extracted and concentrated in the ceramic airfoil portion, which is designed to withstand high temperatures. The metal shank is extracted as a separate cooling zone that operates at lower temperatures, allowing for a shorter, more cost-effective shank design.
Data Source
AI summary
A method may include: in a used metal turbomachine blade including a root including a shank, a platform coupled to the shank and an airfoil coupled to the platform, removing the airfoil, leaving a remaining base including the platform, the shank and the root. The method may also form a radially extending opening through the platform into the shank, and insert a ceramic shank nub extending from a ceramic airfoil into the radially extending opening of the remaining base. The ceramic airfoil is fixedly attached to the remaining base. The method allows reuse of the metal shank while providing the lower cooling requirements of a ceramic airfoil.