Gas Turbine Blade Density Gradient for Centrifugal Load Reduction
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Solution Overview
Problem
Gas turbine engine blades face high mechanical stress due to centrifugal loads and material temperature issues, leading to potential durability and efficiency limitations.
Innovation Solution
A ceramic matrix composite (CMC) blade with a density gradient is manufactured, featuring a decrease in density from the root-end to the tip-end, achieved through controlled chemical vapor infiltration and slurry infiltration processes, using masks to vary the exposure of reactive gases and materials, creating a silicon carbide-rich root-end and high-silicon tip-end.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the blade is made of uniform high-strength material throughout, then the blade can withstand centrifugal loads, but the overall mass of the blade increases
Solution Approach 1:
The blade employs a density gradient where the material composition varies along the blade length. The root portion contains higher density material (70-90% ceramic phase) to withstand high centrifugal loads, while the tip portion contains lower density material (30-50% ceramic phase) to reduce mass. This local variation in material properties optimizes the strength-to-weight ratio by placing material only where structurally necessary.
2Reliability
If the blade root is made of high-density material to withstand stress, then the blade durability improves, but the overall blade efficiency decreases due to increased mass
Solution Approach 1:
The blade utilizes controlled variation in ceramic phase content along its length. The root portion has 70-90% ceramic phase for high strength and durability, while the tip portion has 30-50% ceramic phase for reduced mass. This parameter gradient allows the blade to maintain high reliability at the stress-critical root while improving overall efficiency by reducing the mass of less critical 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
This approach reduces mechanical stress on the blade root, decreases overall blade mass while maintaining durability, and enhances the efficiency of the gas turbine engine by optimizing material distribution.
Implementation Method 1
The porous preform is infiltrated with a chemical vapor matrix material
Implementation Method 2
The porous preform is infiltrated with a ceramic-containing slurry
Data Source
AI summary
A blade for a gas turbine engine, and methods of manufacture of such a blade having a continuous density gradient so that the portion of the blade nearest the rotator shaft is of a higher density than the portion of the blade furthest from the rotator shaft.