Gas Turbine Airfoil Frequency Design
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Solution Overview
Problem
Turbomachinery airfoils face durability issues due to vibrational stresses caused by environmental and thermal loading, leading to shortened lifespan when operating at resonant frequencies, and existing designs lack effective methods for managing these stresses, particularly in compressor sections without cooling passages.
Innovation Solution
The design of turbomachine airfoils with specific dimensions and materials, such as an aluminum-based alloy, that target resonant frequencies of 1056 ± 10% Hz and 1582 ± 10% Hz, corresponding to 1EB and 1T modes, to minimize vibrational stresses and extend the airfoil's lifespan, including methods for repairing damaged airfoils to restore these frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If airfoils operate at resonant frequencies during engine operation, then the airfoil experiences higher vibrational stresses, but the life of the airfoil is significantly shortened
Solution Approach 1:
The patent applies parameter changes by precisely controlling the airfoil's geometric parameters (span, chord length, thickness distribution) and material properties to achieve specific resonant frequencies (1056 Hz and 1582 Hz). This ensures the airfoil's natural frequencies do not coincide with engine operating frequencies, preventing resonant vibrations and extending service life.
2Reliability
If airfoils are designed with specific dimensions and materials to target resonant frequencies, then vibrational stresses are reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter ranges for airfoil design: span of 3.46-3.76 inches, chord length of 1.98-2.28 inches, and specific material properties (density of 0.103 lb/in³, modulus of elasticity of 10.4 Mpsi). These controlled parameter variations provide manufacturing flexibility while maintaining the target resonant frequencies of 1056 Hz and 1582 Hz.
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
The targeted resonant frequencies reduce vibrational stresses, prolonging the airfoil's life and maintaining performance by aligning vibrational modes outside the engine's operating range, thereby enhancing durability and operational efficiency.
Implementation Method 1
Designing airfoils with desirable resonant frequencies can prolong the useful life of engine components, particularly the airfoil itself. The airfoil element includes at least one of a first mode with a frequency of 1056 ± 10% Hz and a second mode with a frequency of 1582 ± 10% Hz.
Data Source
AI summary
A turbomachine airfoil element includes an airfoil that has pressure and suction sides spaced apart from one another in a thickness direction and joined to one another at leading and trailing edges. The airfoil extends in a radial direction a span that is in a range of 3.46-3.76 inch (87.8-95.5 mm). A chord length extends in a chordwise direction from the leading edge to the trailing edge at 50% span and is in a range of 1.98-2.28 inch (50.2-57.8 mm). The airfoil element includes at least one of a first mode with a frequency of 1056 ± 10% Hz and a second mode with a frequency of 1582 ± 10% Hz.