Fuel Feed Strip Bow Shape for Vibration Suppression
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Solution Overview
Problem
Existing fuel injectors for gas turbine engines face challenges with high cycle fatigue due to resonance and vibration, which are often addressed by adding bulk, weight, and complexity to prevent resonance, but these solutions are undesirable for reduced cost, size, and weight requirements.
Innovation Solution
The fuel feed strip is shaped to correspond with specific vibration modes, such as a bow shape, to increase its natural frequency and axial flexibility without additional structure or damping devices, thereby suppressing unwanted vibration modes and reducing the risk of high-cycle fatigue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reinforcing ribs and additional structure are provided to increase the natural frequency of the part, then the natural frequency increases above driving frequencies, but the device complexity and weight increase
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the fuel injector stem, specifically introducing a curved configuration with defined radius of curvature and length ratios. This changes the structural parameters to increase the natural frequency without adding separate reinforcing ribs or additional structure, thereby resolving the contradiction between improving reliability through frequency increase and avoiding device complexity
Solution Approach 2:
The patent applies the curvature principle by configuring the fuel injector stem with a curved shape rather than a straight configuration. The curved stem has a radius of curvature that is a specific percentage of its length, which modifies the vibrational characteristics and increases the natural frequency. This curvature approach achieves frequency enhancement without requiring additional structural elements, thus avoiding increased device complexity
2Reliability
If reinforcing ribs and additional structure are provided to increase the natural frequency of the part, then the natural frequency increases above driving frequencies, but the weight increases
Solution Approach 1:
The patent changes the geometric parameters of the stem by introducing a curved configuration with specific radius-to-length ratios. This parameter modification increases the natural frequency of the stem while avoiding the need for additional reinforcing structure that would add weight. The optimized geometry achieves frequency enhancement through efficient use of existing material rather than adding more mass
3Adaptability or versatility
If the fuel feed strip is made more flexible axially to accommodate thermal expansion, then thermal growth is compensated, but the natural frequency decreases making the part more susceptible to resonance
Solution Approach 1:
The patent applies curvature to the fuel feed strip configuration, forming it into a bowed shape rather than a straight configuration. This curved geometry provides axial flexibility to accommodate thermal expansion while simultaneously increasing the natural frequency by modifying the vibrational mode shapes. The curvature allows the strip to flex axially while maintaining higher frequency characteristics, resolving the contradiction between flexibility and frequency
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 effectively increases the natural frequency of the fuel feed strip while enhancing its axial flexibility, reducing the potential for high-cycle fatigue and accommodating thermal expansion without adding weight or complexity, thus optimizing performance and efficiency.
Implementation Method 1
shaping the fuel feed strip into a shape generally corresponding to a vibration mode shape of a fuel feed strip of a desired shape
Implementation Method 2
increases the natural frequency of the fuel feed strip while enhancing its axial flexibility, reducing the potential for high-cycle fatigue
Data Source
AI summary
A method for increasing and/or suppressing a natural frequency of a fuel injector feed strip while increasing in the axial direction the flexibility of the feed strip, without the use of additional structure or damping devices. More particularly, and by way of example, the present invention provides a fuel feed strip that is shaped in a shape corresponding to a first vibration mode (e.g., a bow shape) of a fuel feed strip of a desired shape (e.g., a straight fuel feed strip). By forming the fuel feed strip in a shape corresponding to a first vibration mode of the fuel feed strip of a desired shape, a vibration mode of the fuel feed strip is suppressed while the axial flexibility of the fuel feed strip is increased.