Gas turbine engine airfoil frequency design

A turbomachine airfoil element includes an airfoil which has pressure and suction sides spaced apart from one another in a depth direction and joined to one another at leading and trailing edges. The airfoil extends in a radial direction a length that’s in a range of 0.75-0.85 inch (19.1-21.6 mm). A chord length extends in a chordwise direction by the leading edge to the trailing edge at 50% length and is in a range of 0.56-0.66 inch (14.2-16.8 mm). The airfoil element includes at least two of a primary mode with a frequency of 2740. +-.10% Hz, another mode with a frequency of 5956. +-.10% Hz, a third mode with a frequency of 6554. +-.10% Hz and a fourth mode with a frequency of 31959. +-.10% Hz.

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BACKGROUND

 
The disclosure relates to turbomachinery. More especially, the disclosure relates to gas turbine engine airfoils and their intended vibrational responses.
 

 
Airfoils of turbine engine blades and vanes are subject to a number of performance-affecting conditions. The airfoils are subject to both ecological vulnerability and mechanical and thermal loading. These variables are significant in each section ofthe motor for a variety of factors. For example, at the fan section of high jump engines, the airfoils have a large diameter with a relatively small thickness. In a high pressure compressor and also at a turbine section, the airfoil is subjected to hightemperatures. Cooling passages are provided in the turbine section airfoils, however, such cooling passages are typically absent in the compressor section. For generators, rotational forces are also a significant dynamic stimulus.
 

 
Vibrational answers of the airfoil could provide an indication of how durable the airfoil will be during engine performance. If an airfoil operates too long in a resonant frequency during engine performance, the lifetime of the airfoil may besignificantly shortened because the airfoil is much more highly stressed. An exemplary vibrational testing method is defined in United States Federal Aviation Administration (FAA) Advisory Circular 38.83-1 (Sep. 8, 2009). Designing airfoils using desirableresonant frequencies may prolong the helpful life of engine components, especially the airfoil itself.
 

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