Aerospace Technic and Technology

The subject of this study is the working process of the axial fan under the annular groove casing treatment of the turbofan engine. The object of the present study is to investigate the fan impeller of a turbofan engine subjected to an annular groove casing treatment. The purpose of this work was to evaluate the effect of an annular groove casing treatment on the pressure ratio of a turbofan engine with a high bypass ratio under different operating conditions. The following tasks were set and solved for their implementation: simulation of the flow in the fan of a turbofan engine with two variants of the annular groove casing treatment for the range of rotation frequencies from 70% to 100%; evaluate the influence of the annular groove casing treatment on the nature of the flow in the peripheral zone of the fan impeller. A numerical experiment method was used to study the flow in the fan stage with the annular groove casing treatment. Flow simulation was performed by solving the system of Navier-Stokes equations, which were closed by the SST turbulent viscosity model, in the ANSYS Student software environment. Meshes were created with the number of nodes – 174377 and 174492 units and the number of elements 963285 and 963195 pcs. respectively for two different configurations. Results: Simulation of the flow in an axial fan with an annular groove casing treatment of a turbofan engine with a high bypass ratio with two different configurations of an annular groove casing treatment was carried out. According to the simulation results, a series of flow characteristics of the fan with two different configurations of the annular groove casing treatment of a turbofan engine with a high bypass ratio at a relative rotation frequency of 70% to 100% were obtained. When the fan is operating at a relative rotation frequency from 100% to 80% with a mass flow rate from 470.45 kg/s to 523...630 kg/s, the pressure ratio in fans with an annular groove casing treatment increases by 2.3...10.5%, and with an increase in mass flow rate, the pressure ratio decreases by 2.4...1.5%. When the fan is operating at a relative frequency of 70%, the presence of an annular groove casing treatment helps to reduce the pressure ratio in the entire range of the considered mass flow rate, thereby reducing the pressure ratio by 1.25%. Analysis of visualizations of streamlines when flowing around the fan impeller showed that the presence of an annular grooves casing treatment has a positive effect on the character of the flow in the impeller, and the zones of reduced speeds behind the blades of the fan are reduced by almost half. The scientific novelty and practical significance lies in the fact that new data on the flow characteristics of the impeller of an axial fan and an annular grooves casing treatment of a turbofan engine with a high bypass ratio were obtained by the method of a numerical experiment, and the results made it possible to form initial data for further research on improving the characteristics of the fan.

annular grooves casing treatment; impeller; fan; pressure ratio; air mass flow rate; gas turbine engine; turbofan engine with a high bypass ratio; blade; turbulent viscosity model; numerical simulation

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