Власні частоти коливань композитної решітчастої дворядної лопатки вентилятора ТРДД

The subject of this study is the natural oscillations of a grid tandem fan blade of a turbofan engine. The object of this study was a tandem grid fan blade. The purpose of this work was to assess the influence of the material on the natural frequencies of the oscillations of a grid tandem fan blade of a turbofan engine. The following tasks were set and solved in the work: conducting a modal analysis of the natural oscillations of a grid tandem fan blade made of a composite material and titanium alloy; construction of a Campbell diagram for a grid tandem fan blade made of a composite material and titanium alloy. The study of the natural oscillations of a fan blade was carried out using a numerical experiment. The natural frequency was obtained for the first ten harmonics. Results: Blades made of Ti-6Al-4V titanium alloy and Epoxy Carbon Woven (395 GPa) Prepreg composite material were studied. Studies have shown that the material selection affects the frequency and mode of the oscillations. For both investigated variants of the grid tandem blades, harmonics exist at which intersections between the first and second blades. The composite grid tandem fan blade has fewer harmonics with the phenomenon of crossing the first and second blade. Campbell diagrams were constructed for the grid tandem fan blades. A grid tandem blade made of a composite material has two, and from a titanium alloy, four resonant frequencies in the range of rotor operating speeds from 2000 rpm. up to 3500 rpm. The weight of the studied composite blade was approximately 5 kg, while the blade made of titanium alloy weighed 15 kg. These studies have shown that a composite grid tandem blade has better characteristics, but the design of such a fan blade row requires improvement. The scientific novelty and practical significance of the conducted research lies in the fact that new data were obtained on the natural oscillations of the grid tandem fan blades of a turbofan engine made of a composite material and a titanium alloy. The obtained data will help to create promising gas turbine engines with improved characteristics.