Gas Turbine Airfoil Frequency Design
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Solution Overview
Problem
Turbomachinery airfoils in gas turbine engines face durability issues due to vibrational stresses caused by resonant frequencies, which can lead to reduced lifespan if they operate at these frequencies during engine operation, especially in high-pressure compressor and turbine sections where cooling is limited.
Innovation Solution
Designing airfoils with specific dimensions and frequencies, such as a radial span of 1.01-1.15 inches and chord length of 0.54-0.66 inches, and defining modes like 1EB, 1T, 2EB, and 2T with precise frequency ranges to avoid resonant conditions, using nickel-based superalloys with specific density and elasticity, and potentially repairing damaged airfoils to restore these frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If airfoils are designed with standard dimensions and operating parameters, then engine performance is maintained, but vibrational stresses cause reduced lifespan due to resonant frequencies
Solution Approach 1:
The patent applies parameter changes by modifying the airfoil's geometric dimensions (span, chord length, thickness) and material properties (density, modulus of elasticity) to shift the natural frequencies away from resonant conditions. Specifically, the airfoil span is set to 1.01-1.15 inches and chord length to 0.54-0.66 inches, which changes the vibrational characteristics to avoid harmful resonance during engine operation.
Solution Approach 2:
The patent implements preliminary action by pre-designing the airfoil with specific frequency characteristics before operation. The airfoil is engineered to have natural frequencies that deliberately avoid resonant frequencies during normal engine operation, preventing vibrational stresses before they can occur during service.
2Reliability
If airfoil dimensions are modified to change vibrational frequencies, then resonant conditions are avoided, but manufacturing precision requirements increase
Solution Approach 1:
The patent defines specific parameter ranges for the airfoil dimensions (span: 1.01-1.15 inches, chord length: 0.54-0.66 inches) that achieve the desired frequency characteristics. By providing ranges rather than single values, the design accommodates normal manufacturing variations while maintaining the frequency control needed to avoid resonance.
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 designed airfoils experience reduced vibrational stresses, prolonging their lifespan by avoiding resonant frequencies during operation, thus enhancing the durability and performance of gas turbine engine components.
Implementation Method 1
Vibrational responses of the airfoil can provide an indication of how durable the airfoil will be during engine operation
Implementation Method 2
If an airfoil operates too long at a resonant frequency during engine operation, the life of the airfoil may be significantly shortened
Implementation Method 3
using nickel-based superalloys with specific density and elasticity
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 1.01-1.15 inch (25.7-29.3 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 0.54-0.66 inch (13.6-16.8 mm). The airfoil element includes at least two of a first mode with a frequency of 2033 ± 15% Hz, a second mode with a frequency of 7023 ± 15% Hz, a third mode with a frequency of 12082 ± 15% Hz and a fourth mode with a frequency of 19769 ± 15% Hz.